一、 基本说明
keepalived.conf是配置文件，其中描述所有的 Keepalived 关键字。
关键字需要放置在含有等级结构的块和子块中，每一层都由成对的大括号 {
和
} 组成。
注释使用 # 或 ! , 它们可放在一行的开头， 也可以放在一行中的任何地方，直到一行的结尾，都会被看做注释。
关键字 include允许包含其他配置文件, 就行 Nginx 的配置文件一样。
下面的配置说明中的参数语法：
- <BOOL>是
on|off|true|false|yes|no之一 - <TIMER>是以秒为单位的时间值，包括小数秒，例如2.71828或3;计时器的分辨率是微
秒。
二、 配置文件结构
Keepalived 配置文件围绕一组配置块进行连接。
每个块都针对特定功能，并有专门的守护进程。
! Configuration File for keepalived
global_defs {
全局配置块
}
vrrp_instance VI_1 {
vrrpd 实例配置块, 可以配置多个
}
virtual_server 192.168.200.100 443 {
LVS 配置块, 可以配置多个
}
三、 全局配置块
global_defs {
notification_email {
# 接收通知邮件的电子邮箱账户列表
# 注意发送邮件需要本机开启邮件服务，目前一般企业不用这种方式
# 而是使用 zabbix 等监控实现
[email protected]
[email protected]
[email protected]
}
# 指定发件人，这将会显示在发送的邮件中
notification_email_from [email protected]
# 用于发送邮件通知的SMTP服务器
smtp_server 127.0.0.1
# 指定SMTP流处理的超时时间
smtp_connect_timeout 30
# 标识机器的字符串（不必是主机名）。
router_id LVS_DEVEL
# 检查收到的VRRP 组播中的所有地址可能很耗时。
# 设置此标志意味着，如果组播与先前收到的组播来自同一主路由器，则不会进行检查。
vrrp_skip_check_adv_addr
# 强制严格遵守VRRP协议。 这将禁止：
＃0 VIP
＃单播对等
＃VRRP版本2中的IPv6地址
vrrp_strict
vrrp_garp_interval 0.001
vrrp_gna_interval 0.000001
}
四、 VRRPD 实例配置块
配置示例
vrrp_instance VI_1 {
# 实例名称, 所有机器应保持一致
# 此 keepalived 的角色，在一组 keepalived 中只允许有一个 MASTER
# 其他的应该设置为 BACKUP.
# 实际上，一旦其他机器启动，将举行一次选举，
# 并且具有最高优先级的计算机将成为MASTER。
# 因此，这里的条目并不重要，只是有利于可读性。
state MASTER
# 绑定 vrrp 的内部接口，用于发送心跳信息（组播信息，地址是:224.0.0.18）
interface eth0
# 从1到255的任意唯一数字
# 用于区分在同一NIC（并因此使用的同一套接字）上运行的vrrpd的多个实例
# 同一个集群中的每个调度器上应该设置为一致
virtual_router_id 51
# 优先级，用于选举 MASTER
# 要想成为 MASTER, 使其比其他机器多50
priority 100
# VRRP 组播通告间隔，单位是秒（例如0.92）。
advert_int 1
# 认证信息，所有的机器上应该一致
authentication {
auth_type PASS
auth_pass 1111
}
# VIP 地址，会随着角色转换而改变，VIP 总是在 MASTER 上被绑定。
# 所有的机器应设置为一样的内容
virtual_ipaddress {
192.168.122.100
}
notify_master /path_to_script/script_master.sh
(or notify_master “ /path_to_script/script_master.sh <arg_list>”)
notify_backup /path_to_script/script_backup.sh
(or notify_backup “ /path_to_script/script_backup.sh <arg_list>”)
notify_fault /path_to_script/script_fault.sh
(or notify_fault “ /path_to_script/script_fault.sh <arg_list>”)
}
配置项参考
| 关键字 | 定义 | 类型 |
|---|---|---|
| vrrp_instance | 标识VRRP实例定义块 | Block |
| state | 在标准使用中指定实例状态 | |
| interface | 指定实例运行所要用到的网络接口 | string |
| mcast_src_ip | 指定VRRP通告的IP头的源地址 | |
| lvs_sync_daemon_inteface | 指定LVS sync_daemon运行所要用到的网络接口 | string |
| virtual_router_id | 指定实例所属的VRRP路由器ID | numerical |
| priority | 指定实例在VRRP路由器中的优先级 | numerical |
| advert_int | 以秒为单位指定通告的间隔时间(设置为1) | numerical |
| smtp_alert | 激活MASTER状态转换的SMTP通知 | |
| authentication | 标识VRRP认证定义块 | Block |
| auth_type | 指定要使用哪种身份认证(PASS | AH) |
| auth_pass | 指定要使用的密码字符串 | string |
| virtual_ipaddress | 标识VRRP VIP定义块 | Block |
| virtual_ipaddress_excluded | 标识VRRP VIP排除定义块 | Block |
| notify_master | 指定在切换到master时要执行的脚本 | path |
| notify_backup | 指定在切换到backup时要执行的脚本 | path |
| notify_fault | 指定在切换到故障状态时要执行的脚本 | path |
五、 LVS 配置块
假如使用 Keepalived + LVS 应该设置这一部分，假如高可用针对的不是 LVS，则不需要设置此部分。
virtual_server 192.168.122.100 80 {
#LVS配置
delay_loop 6 #健康检查rs时间间隔
lb_algo rr #LVS调度算法
lb_kind DR #LVS集群模式（路由模式）
protocol TCP #健康检查使用的协议
real_server 192.168.122.10 80 {
weight 1
inhibit_on_failure #当该节点失败时，把权重设置为0，而不是从IPVS中删除
TCP_CHECK {
#健康检查
connect_port 80 #检查的端口
connect_timeout 3 #连接超时的时间, 单位为: 秒
}
}
real_server 192.168.122.20 80 {
weight 1
inhibit_on_failure
TCP_CHECK {
connect_timeout 3
connect_port 80
}
}
}
# LVS 的 VIP，要和 virtual_ipaddress 中值一致
virtual_server 192.168.122.100 443 {
delay_loop 6 # 检查 RS 的轮询间隔，单位秒
lvs_sched rr # LVS 调度算法
lvs_method DR # LVS 的工作模式,默认 NAT
persistence_timeout 50 # LVS持久性超时（以秒为单位），默认为6分钟
protocol TCP # 健康检查使用的协议
real_server 192.168.122.10 443 {
# 权重
weight 1
# Healthchecker检测到故障时将权重设置为0，默认配置文件中没有
inhibit_on_failure
SSL_GET {
url {
path /
digest ff20ad2481f97b1754ef3e12ecd3a9cc
}
url {
path /mrtg/
digest 9b3a0c85a887a256d6939da88aabd8cd
}
connect_timeout 3
retry 3
delay_before_retry 3
}
}
}
| 关键字 | 定义 | 类型 |
|---|---|---|
| virtual_server | 标识虚拟服务器定义块 | Block |
| fwmark | 指定虚拟服务器是FWMARK | |
| delay_loop | 以秒为单位指定检查之间的间隔时间 | numerical |
| lb_algo | 选择一个特定的调度程序(rr | wrr |
| lb_kind | 选择一个特定的转发方法(NAT | DR |
| persistence_timeout | 为持久连接指定超时时间 | numerical |
| persistence_granularity | 为持久连接指定粒度掩码 | |
| virtualhost | 指定用于HTTP | SSL_GET的虚拟主机 |
| protocol | 指定协议类型(TCP | UDP) |
| sorry_server | 当所有真实服务器都宕掉时添加到池中的服务器 | |
| real_server | 指定一个真实服务器成员 | |
| weight | 为真实服务器指定负载均衡的权重 | numerical |
| TCP_CHECK | 使用TCP连接检查真实服务器的可用性 | |
| MISC_CHECK | 使用用户定义的脚本检查真实服务器的可用性 | |
| misc_path | 标识要运行脚本的完整路径 | path |
| HTTP_GET | 使用HTTP GET请求检查真实服务器的可用性 | |
| SSL_GET | 使用HTTPS GET请求检查真实服务器的可用性 | |
| url | 标识url定义块 | Block |
| path | 指定url路径 | alphanum |
| digest | 指定特定url路径的摘要 | alphanum |
| connect_port | 指定连接远程服务器的TCP端口 | numerical |
| connect_timeout | 指定连接远程服务器的超时时间 | numerical |
| retry | 最大重试次数 | numerical |
| delay_before_retry | 两次连续重试之间的延迟 | numerical |
类型“path”指的是被调用脚本的完整路径。对于需要参数的脚本，路径和参数必须用双引号括起来。
六、VRRP script
vrrp_script 关键字用于设置检查脚本，主要是检查 keepalived 程序自身是否正常，比如是否正常向 224.0.0.18 发送组播,可以防止脑裂。 此配置块是独立的，也就是说它是顶级配置块，需要顶满格写。注意：需要至少有一个实例配置使用此脚本，此脚本才会运行。
track_script 用于添加一个跟踪脚本到 VRRP 实例中，这个脚本就是 vrrp_script 配置块中定义的，用于监控 VRRP 实例是否正常。
1 vrrp_script
vrrp_script <SCRIPT_NAME> {
＃要执行的脚本的路径, 假如有参数，使用双引号引起来 quoted 是双引号的意思
script <STRING> | <QUOTED-STRING>
# 脚本调用之间的秒数（默认值：1秒）
interval <INTEGER>
# 多少秒后，脚本被视为执行失败
timeout <INTEGER>
＃通过此权重调整优先级，（默认值：0）
＃有关反转的描述，请参见track_script。
＃'weight 0 reverse' 将在脚本启动时导致vrrp实例关闭，反之亦然。。
weight <INTEGER:-253..253> [reverse]
＃进行OK转换所需的成功次数
rise <INTEGER>
＃KO转换所需的成功次数
fall <INTEGER>
＃用这里设置的用户名和组执行此脚本。
＃组默认为用户组
user USERNAME [GROUPNAME]
＃假设脚本最初处于失败状态
init_fail
}
该脚本将每隔秒执行一次。
默认权重等于0，这意味着在脚本连续失败后，任何监视脚本的VRRP实例都将转换为故障状态。
此后，连续成功将导致VRRP实例退出故障状态，除非由于它们正在跟踪的其他脚本或接口而使它们也处于故障状态。
2 track_script
vrrp_instance <STRING> {
...略...
track_script {
<SCRIPT_NAME>
}
}
<SCRIPT_NAME> 是
vrrp_script配置块中的名称,例如：vrrp_script check_nginx{ ... }
track_script中 <SCRIPT_NAME> 的值应该是check_nginx
官方配置文件文档说明
NAME
keepalived.conf - configuration file for Keepalived
DESCRIPTION
keepalived.conf is the configuration file which
describes all the Keepalived keywords. Keywords are placed in hierar-
chies of blocks and subblocks, each layer being delimited by '{' and
'}' pairs.
Comments start with '#' or '!' to the end of the line and can start
anywhere in a line.
The keyword 'include' allows inclusion of other configuration files
from within the main configuration file, or from subsequently included
files.
The format of the include directive is:
include FILENAME
FILENAME can be a fully qualified or relative pathname, and can include
wildcards, including csh style brace expressions such as
"{foo/{,cat,dog},bar}" if glob() supports them.
After opening an included file, the current directory is set to the
directory of the file itself, so any relative paths included from a
file are relative to the directory of the including file itself.
Note: This documentation MUST be considered as THE
exhaustive source of information in order to configure Keepalived. This
documenation is supported and maintained by Keepalived Core-Team.
PARAMETER SYNTAX
<BOOL> is one of on|off|true|false|yes|no
<TIMER> is a time value in seconds, including
fractional seconds, e.g. 2.71828 or 3; resolution of timer is micro-
seconds.
SCRIPTS
There are three classes of scripts can be configured to be executed.
(a) Notify scripts that are run when a vrrp instance or vrrp group
changes state, or a virtual server quorum changes between up and down.
(b) vrrp tracking scripts that will cause vrrp instances to go down it
they exit a non-zero exist status, or if a weight is specified will add
or subtract the weight to/from the priority of that vrrp instance.
(c) LVS checker misc scripts that will cause a real server to be con-
figured down if they exit with a non-zero status.
By default the scripts will be executed by user keepalived_script if
that user exists, or if not by root, but for each script the user/group
under which it is to be executed can be specified.
There are significant security implications if scripts are executed
with root privileges, especially if the scripts themselves are modifi-
able or replaceable by a non root user. Consequently, security checks
are made at startup to ensure that if a script is executed by root,
then it cannot be modified or replaced by a non root user.
All scripts should be written so that they will terminate on receipt of
a SIGTERM signal. Scripts will be sent SIGTERM if their parent termi-
nates, or it is a script the keepalived is awaiting its exit status and
it has run for too long.
Quoted strings
Quoted strings are specified between " characters; more specifically a
string will only end after a quoted string if there is whitespace
afterwards. For example:
"abcd" efg h jkl "mnop"
will be the single string "abcd efg h jkl mnop", i.e. the embedded "
characters are removed.
Quoted strings can also have escaped characters, like the shell. \a,
\b, \E, \f, \n, \r, \t, \v, \nnn and \xXX (where nnn is up to 3 octal
digits, and XX is any sequence of hex digits) and \cC (which produces
the control version of character C) are all supported. \C for any other
character C is just treated as an escaped version of character C, so \\
is a \ character and \" will be a " character, but it won't start or
terminate a quoted string.
For specifying scripts with parameters, unquoted spaces will separate
the parameters. If it is required for a parameter to contain a space,
it should be enclosed in single quotes (').
CONFIGURATION PARSER
Traditionally the configuration file parser has not been one of the
strengths of keepalived. Lot of efforts have been put to correct this
even if this is not the primal goal of the project.
TOP HIERACHY
Keepalived configuration file is articulated around a set of configura-
tion blocks. Each block is focusing and targetting a specific daemon
family feature. These features are:
GLOBAL CONFIGURATION
BFD CONFIGURATION
VRRPD CONFIGURATION
LVS CONFIGURATION
GLOBAL CONFIGURATION
contains subblocks of Global definitions, Linkbeat interfaces,
Static track groups, Static addresses, Static routes, and
Static rules
Global definitions
# Following are global daemon facilities for running
# keepalived in a separate network namespace:
# --
# Set the network namespace to run in.
# The directory /var/run/keepalived will be created as an
# unshared mount point, for example for pid files.
# syslog entries will have _NAME appended to the ident.
# Note: the namespace cannot be changed on a configuration reload.
net_namespace NAME
# Add the IPVS configuration in the specified net namespace. It allows to easily
# split the VIP traffic on a given namespace and keep the healthchecks traffic
# in another namespace. If NAME is not specified, then the default namespace
# will be used.
net_namespace_ipvsNAME
# ipsets wasn't network namespace aware until Linux 3.13, and so
# if running with # an earlier version of the kernel, by default
# use of ipsets is disabled if using a namespace and vrrp_ipsets
# has not been specified. This options overrides the default and
# allows ipsets to be used with a namespace on kernels prior to 3.13.
namespace_with_ipsets
# If multiple instances of keepalived are run in the same namespace,
# this will create pid files with NAME as part of the file names,
# in /var/run/keepalived.
# Note: the instance name cannot be changed on a configuration reload
instance NAME
# Create pid files in /var/run/keepalived
use_pid_dir
# Poll to detect media link failure using ETHTOOL, MII or ioctl interface
# otherwise uses netlink interface.
linkbeat_use_polling
# Time for main process to allow for child processes to exit on termination
# in seconds. This can be needed for very large configurations.
# (default: 5)
child_wait_time SECS
# Global definitions configuration block
global_defs {
# Set the process names of the keepalived processes to the default values:
# keepalived, keepalived_vrrp, keepalived_ipvs, keepalived_bfd
process_names
# Specify the individual process names
process_name NAME
vrrp_process_name NAME
ipvs_process_name NAME
bfd_process_name NAME
# The startup and shutdown scripts are run once, when keepalived starts
# before any child processes are run, and when keepalived stops after
# all child processes have terminated, respectively.
# The original motivation for adding this feature was that although
# keepalived can setup IPVS configuration using firewall marks, there
# was no mechanism for adding configuration to set the firewall marks
# (or for removing it afterwards).
# This feature can also be used to setup the iptables framework required
# if using iptables (see vrrp_iptables option below), modify interface
# settings, or anything else that can be done from a script or program.
# Only one startup script and one shutdown script can be specified.
# The timeouts (in seconds default 10 seconds) are the time allowed for
# scripts to run; if the timeout expires the scripts will be killed (this
# is to stop keepalived hanging waiting for the scripts to terminate).
startup_script SCRIPT_NAME [username [groupname]]
startup_script_timeout SECONDS # range [1,1000]
shutdown_script SCRIPT_NAME [username [groupname]]
shutdown_script_timeout SECONDS # range [1,1000]
# Set of email To: notify
notification_email {
[email protected]
...
}
# email from address that will be in the header
# (default: keepalived@<local host name>)
notification_email_from [email protected]
# Remote SMTP server used to send notification email.
# IP address or domain name with optional port number.
# (default port number: 25)
smtp_server 127.0.0.1 [<PORT>]
# Name to use in HELO messages.
# (default: local host name)
smtp_helo_name <STRING>
# SMTP server connection timeout in seconds.
smtp_connect_timeout 30
# Sets default state for all smtp_alerts
smtp_alert <BOOL>
# Sets default state for vrrp smtp_alerts
smtp_alert_vrrp <BOOL>
# Sets default state for checker smtp_alerts
smtp_alert_checker <BOOL>
# Sets logging all checker failes while checker up
checker_log_all_failures <BOOL>
# Don't send smtp alerts for fault conditions
no_email_faults
# String identifying the machine (doesn't have to be hostname).
# (default: local host name)
router_id <STRING>
# Multicast Group to use for IPv4 VRRP adverts
# (default: 224.0.0.18)
vrrp_mcast_group4 224.0.0.18
# Multicast Group to use for IPv6 VRRP adverts
# (default: ff02::12)
vrrp_mcast_group6 ff02::12
# sets the default interface for static addresses.
# (default: eth0)
default_interface p33p1.3
# The sync daemon as provided by the IPVS kernel code only supports
# one master and one backup daemon instance at a time to synchronize
# the IPVS connection table.
# See ipvsadm(8) man page for more details of the sync daemon.
# Parameters are binding interface, and optional:
# inst VRRP_INSTANCE (inst can be omitted for backward compatibility)
# syncid (0 to 255) for lvs syncd, default is the VRID of vrrp instance,
# or 0 if no vrrp instance
# maxlen (1..65507) maximum packet length (limit is mtu - 20 - 8)
# port (1..65535) UDP port number to use, default 8848
# ttl (1..255)
# group - multicast group address(IPv4 or IPv6), default 224.0.0.81
# If VRRP_INSTANCE is not specified, both the master and backup sync daemons
# will be run as long as keepalived is running, otherwise the sync daemon
# master/backup state tracks the state of the specified vrrp instance: if
# the vrrp instance is in master state, only the master sync daemon will run,
# if the vrrp instance is not master, only the backup sync daemon will run.
# NOTE: maxlen, port, ttl and group are only available on Linux 4.3 or later.
# See kernel source doc/Documentation/networking/ipvs-sysctl.txt for details of
# parameters controlling IPVS and the sync daemon.
# /proc/net/ip_vs* provide some details about the state of IPVS.
lvs_sync_daemon <INTERFACE> [[inst] <VRRP_INSTANCE>] [id <SYNC_ID>] \
[maxlen <LEN>] [port <PORT>] [ttl <TTL>] [group <IP ADDR>]
# flush any existing LVS configuration at startup
lvs_flush
# flush remaining LVS configuration at shutdown
# If VS is specified, remove each keepalived managed virtual
# server without explicitly removing the real servers (the kernel will
# remove them).
lvs_flush_onstop [VS]
# delay for second set of gratuitous ARPs after transition to MASTER.
# in seconds, 0 for no second set.
# (default: 5)
vrrp_garp_master_delay 10
# number of gratuitous ARP messages to send at a time after
# transition to MASTER.
# (default: 5)
vrrp_garp_master_repeat 1
# delay for second set of gratuitous ARPs after lower priority
# advert received when MASTER.
vrrp_garp_lower_prio_delay 10
# number of gratuitous ARP messages to send at a time after
# lower priority advert received when MASTER.
vrrp_garp_lower_prio_repeat 1
# minimum time interval for refreshing gratuitous ARPs while MASTER.
# in seconds.
# (default: 0 (no refreshing))
vrrp_garp_master_refresh 60
# number of gratuitous ARP messages to send at a time while MASTER
# (default: 1)
vrrp_garp_master_refresh_repeat 2
# Delay in ms between gratuitous ARP messages sent on an interface
# decimal, seconds (resolution usecs).
# (default: 0)
vrrp_garp_interval 0.001
# Delay in ms between unsolicited NA messages sent on an interface
# decimal, seconds (resolution usecs).
# (default: 0)
vrrp_gna_interval 0.000001
# By default keepalived sends 5 gratuitions ARP/NA messages at a
# time, and after transitioning to MASTER sends a second block of
# 5 messages 5 seconds later.
# With modern switches this is unnecessary, so setting vrrp_min_garp
# causes only one ARP/NA message to be sent, with no repeat 5 seconds
# later.
vrrp_min_garp [<BOOL>]
# If a lower priority advert is received, don't send another advert.
# This causes adherence to the RFCs. Defaults to false, unless
# strict_mode is set.
vrrp_lower_prio_no_advert [<BOOL>]
# If we are master and receive a higher priority advert, send an advert
# (which will be lower priority than the other master), before we
# transition to backup. This means that if the other master has
# garp_lower_priority_repeat set, it will resend garp messages.
# This is to get around the problem of their having been two simultaneous
# masters, and the last GARP messages seen were from us.
vrrp_higher_prio_send_advert [<BOOL>]
# Set the default VRRP version to use
# (default: 2, but IPv6 instances will use version 3)
vrrp_version <2 or 3>
# keepalived uses a firewall (either nftables or iptables) for two purposes:
# i) To implement no_accept mode
# ii) To stop IGMP/MLD packets being sent on VMAC interfaces, and to move
# them onto the underlying interface.
# If both vrrp_iptables and vrrp_nftables are specified, keepalived will use
# nftables and not iptables. Similarly, if the iptables command is generating
# nftables configuration, or there is no iptables command installed,
# keepalived will use nftables rather than iptables.
# If neither vrrp_nftables or vrrp_iptables are specified but VMACs are in use
# or no_accept is specified, keepalived will use nftables if it is available.
# Use nftables as the firewall.
# TABLENAME must not exist, and must be different for each
# instance of keepalived running in the same network namespace.
# Default tablename is keepalived, and priority is -1.
# keepalived will create base chains in the table.
# counters means counters are added to the rules (primarily for
# debugging purposes).
# ifindex means create IPv6 link local sets using ifindex rather
# than ifnames. This is the default unless the vrrp_instance has
# set dont_track_primary. The alternative is to use interface names
# as part of the set key, but the nft utility prior to v0.8.3 will
# then not output interface names properly.
nftables [TABLENAME]
nftables_priority PRIORITY
nftables_counters
nftables_ifindex
# Use iptables as the firewall.
# Note: it is necessary for the specified chain to exist in
# the iptables and/or ip6tables configuration, and for the chain
# to be called from an appropriate point in the iptables configuration.
# It will probably be necessary to have this filtering after accepting
# any ESTABLISHED,RELATED packets, because IPv4 might select the VIP as
# the source address for outgoing connections.
# (default: INPUT)
vrrp_iptables keepalived
# or for outbound filtering as well
# Note, outbound filtering won't work with IPv4, since the VIP can be
# selected as the source address for an outgoing connection. With IPv6
# this is unlikely since the addresses are deprecated.
vrrp_iptables keepalived_in keepalived_out
# or to to use default chains (INPUT and OUTPUT)
vrrp_iptables
# Keepalived may have the option to use ipsets in conjunction with
# iptables. If so, then the ipset names can be specified, defaults
# as below. If no names are specified, ipsets will not be used,
# otherwise any omitted names will be constructed by adding "_if"
# and/or "6" and _igmp/_mld to previously specified names.
vrrp_ipsets [keepalived [keepalived6 [keepalived_if6 [keepalived_igmp [keepalived_mld]]]]]
# The following enables checking that when in unicast mode, the
# source address of a VRRP packet is one of our unicast peers.
vrrp_check_unicast_src
# Checking all the addresses in a received VRRP advert can be time
# consuming. Setting this flag means the check won't be carried out
# if the advert is from the same master router as the previous advert
# received.
# (default: don't skip)
vrrp_skip_check_adv_addr
# Enforce strict VRRP protocol compliance. This will prohibit:
# 0 VIPs
# unicast peers
# IPv6 addresses in VRRP version 2
vrrp_strict
# Send vrrp instance priority notifications on notify FIFOs.
vrrp_notify_priority_changes <BOOL>
# The following options can be used if vrrp, checker or bfd processes
# are timing out. This can be seen by a backup vrrp instance becoming
# master even when the master is still running, because the master or
# backup system is too busy to process vrrp packets.
# --
# keepalived can, if it detects that it is not running sufficiently
# soon after a timer should expire, increase its priority, first
# of all switching to realtime scheduling, and if that is not
# sufficient, it will then increase its realtime priority by one each
# time it detects a further delay in running. If the event that realtime
# scheduling is enabled, RLIMIT_RTTIME will be set, using the values for
# {bfd,checker,vrrp}_rlimit_rttime (see below). These values may need
# to be increased for slower processors.
# --
# To limit the maximum increased automatic priority, specify the following
# (0 doesn't use automatic priority increases, and is the default. -1 disables
# the warning message at startup). Omitting the priority sets the maximum value.
max_auto_priority [<-1 to 99>] # 99 is really sched_get_priority_max(SCHED_RR)
# Minimum delay in microseconds after timer expires before keeplalived is
# scheduled after which the process priority will be auto incremented
# (default is 1000000 usecs (1 second), maximum is 10000000 (10 seconds))
min_auto_priority_delay <delay in usecs>
# Set the vrrp child process priority (Negative values increase priority)
vrrp_priority <-20 to 19>
# Set the checker child process priority
checker_priority <-20 to 19>
# Set the BFD child process priority
bfd_priority <-20 to 19>
# Set the vrrp child process non swappable
vrrp_no_swap
# Set the checker child process non swappable
checker_no_swap
# Set the BFD child process non swappable
bfd_no_swap
# The following options can be used to force vrrp, checker and bfd
# processes to run on a restricted CPU set.
# You can either bind processes to a single CPU or define a set of
# cpu. In that last case Linux kernel will be restricted to that cpu
# set during scheduling. Forcing process binding to single CPU can
# increase performances on heavy loaded box.
# INTEGER following configuration keyword are representing cpu_id
# as shown in /proc/cpuinfo on line "processor:"
# --
# Set CPU Affinity for the vrrp child process
vrrp_cpu_affinity <INTEGER> [<INTERGER>]...[<INTEGER>]
# Set CPU Affinity for the checker child process
checker_cpu_affinity <INTEGER> [<INTERGER>]...[<INTEGER>]
# Set CPU Affinity for the bfd child process
bfd_cpu_affinity <INTEGER> [<INTERGER>]...[<INTEGER>]
# Set the vrrp child process to use real-time scheduling
# at the specified priority
vrrp_rt_priority <1..99>
# Set the checker child process to use real-time scheduling
# at the specified priority
checker_rt_priority <1..99>
# Set the BFD child process to use real-time scheduling
# at the specified priority
bfd_rt_priority <1..99>
# Set the limit on CPU time between blocking system calls,
# in microseconds
# (default: 10000)
vrrp_rlimit_rttime >=2
checker_rlimit_rttime >=2
bfd_rlimit_rttime >=2
# If Keepalived has been build with SNMP support, the following
# keywords are available.
# Note: Keepalived, checker and RFC support can be individually
# enabled/disabled
# --
# Specify socket to use for connecting to SNMP master agent
# (see source module keepalived/vrrp/vrrp_snmp.c for more details)
# (default: unix:/var/agentx/master)
snmp_socket udp:1.2.3.4:705
# enable SNMP handling of vrrp element of KEEPALIVED MIB
enable_snmp_vrrp
# enable SNMP handling of checker element of KEEPALIVED MIB
enable_snmp_checker
# enable SNMP handling of RFC2787 and RFC6527 VRRP MIBs
enable_snmp_rfc
# enable SNMP handling of RFC2787 VRRP MIB
enable_snmp_rfcv2
# enable SNMP handling of RFC6527 VRRP MIB
enable_snmp_rfcv3
# enable SNMP traps
enable_traps
# If Keepalived has been build with DBus support, the following
# keywords are available.
# --
# Enable the DBus interface
enable_dbus
# Name of DBus service
# Useful if you want to run multiple keepalived processes with DBus enabled
# (default: org.keepalived.Vrrp1)
dbus_service_name SERVICE_NAME
# Specify the default username/groupname to run scripts under.
# If this option is not specified, the user defaults to keepalived_script
# if that user exists, otherwise root.
# If groupname is not specified, it defaults to the user's group.
script_user username [groupname]
# Don't run scripts configured to be run as root if any part of the path
# is writable by a non-root user.
enable_script_security
# Rather than using notify scripts, specifying a fifo allows more
# efficient processing of notify events, and guarantees that they
# will be delivered in the correct sequence.
# NOTE: the FIFO names must all be different
# --
# FIFO to write notify events to
# See vrrp_notify_fifo and lvs_notify_fifo for format of output
# For further details, see the description under vrrp_sync_group.
# see doc/samples/sample_notify_fifo.sh for sample usage.
notify_fifo FIFO_NAME [username [groupname]]
# script to be run by keepalived to process notify events
# The FIFO name will be passed to the script as the last parameter
notify_fifo_script STRING|QUOTED_STRING [username [groupname]]
# FIFO to write vrrp notify events to.
# The string written will be a line of the form: INSTANCE "VI_1" MASTER 100
# and will be terminated with a new line character.
# For further details of the output, see the description under vrrp_sync_group
# and doc/samples/sample_notify_fifo.sh for sample usage.
vrrp_notify_fifo FIFO_NAME [username [groupname]]
# script to be run by keepalived to process vrrp notify events
# The FIFO name will be passed to the script as the last parameter
vrrp_notify_fifo_script STRING|QUOTED_STRING [username [groupname]]
# FIFO to write notify healthchecker events to
# The string written will be a line of the form:
# VS [192.168.201.15]:tcp:80 {UP|DOWN}
# RS [1.2.3.4]:tcp:80 [192.168.201.15]:tcp:80 {UP|DOWN}
# and will be terminated with a new line character.
lvs_notify_fifo FIFO_NAME [username [groupname]]
# script to be run by keepalived to process healthchecher notify events
# The FIFO name will be passed to the script as the last parameter
lvs_notify_fifo_script STRING|QUOTED_STRING [username [groupname]]
# Allow configuration to include interfaces that don't exist at startup.
# This allows keepalived to work with interfaces that may be deleted and restored
# and also allows virtual and static routes and rules on VMAC interfaces.
# allow_if_changes allows an interface to be deleted and recreated with a
# different type or underlying interface, eg changing from vlan to macvlan
# or changing a macvlan from eth1 to eth2. This is predominantly used for
# reporting duplicate VRID errors at startup if allow_if_changes is not set.
dynamic_interfaces [allow_if_changes]
# The following options are only needed for large configurations, where either
# keepalived creates a large number of interface, or the system has a large
# number of interface. These options only need using if
# "Netlink: Receive buffer overrun" messages are seen in the system logs.
# If the buffer size needed exceeds the value in /proc/sys/net/core/rmem_max
# the corresponding force option will need to be set.
# --
# Set netlink receive buffer size. This is useful for
# very large configurations where a large number of interfaces exist, and
# the initial read of the interfaces on the system causes a netlink buffer
# overrun.
vrrp_netlink_cmd_rcv_bufs BYTES
vrrp_netlink_cmd_rcv_bufs_force <BOOL>
vrrp_netlink_monitor_rcv_bufs BYTES
vrrp_netlink_monitor_rcv_bufs_force <BOOL>
# The vrrp netlink command and monitor socket the checker command and
# and monitor socket and process monitor buffer sizes can be independently set.
# The force flag means to use SO_RCVBUFFORCE, so that the buffer size
# can exceed /proc/sys/net/core/rmem_max.
lvs_netlink_cmd_rcv_bufs BYTES
lvs_netlink_cmd_rcv_bufs_force <BOOL>
lvs_netlink_monitor_rcv_bufs BYTES
lvs_netlink_monitor_rcv_bufs_force <BOOL>
# As a guide for process_monitor_rcv_bufs for 1400 processes terminating
# simultaneously, 212992 (the default on some systems) is insufficient, whereas
# 500000 is sufficient.
process_monitor_rcv_bufs BYTES
process_monitor_rcv_bufs_force <BOOL>
# When a socket is opened, the kernel configures the max rx buffer size for
# the socket to /proc/sys/net/core/rmem_default. On some systems this can be
# very large, and even generally this can be much larger than necessary.
# This isn't a problem so long as keepalived is reading all queued data from
# it's sockets, but if rmem_default was set sufficiently large, and if for
# some reason keepalived stopped reading, it could consume all system memory.
# The vrrp_rx_bufs_policy allows configuring of the rx bufs size when the
# sockets are opened. If the policy is MTU, the rx buf size is configured
# to the total of interface's MTU * vrrp_rx_bufs_multiplier for each vrrp
# instance using the socket. Likewise, if the policy is ADVERT, then it is
# the total of each vrrp instances advert packet size * multiplier.
# (default: use system default)
vrrp_rx_bufs_policy [MTU|ADVERT|NUMBER]
# (default: 3)
vrrp_rx_bufs_multiplier NUMBER
# Send notifies at startup for real servers that are starting up
rs_init_notifies
# Don't send an email every time a real server checker changes state;
# only send email when a real server is added or removed
no_checker_emails
# The umask to use for creating files. The number can be specified in hex, octal
# or decimal. BITS are I{R|W|X}{USR|GRP|OTH}, e.g. IRGRP, separated by '|'s.
# The default umask is IWGRP | IWOTH. This option cannot override the
# command-line option.
umask [NUMBER|BITS]
# On some systems when bond interfaces are created, they can start passing traffic
# and then have a several second gap when they stop passing traffic inbound. This
# can mean that if keepalived is started at boot time, i.e. at the same time as
# bond interfaces are being created, keepalived doesn't receive adverts and hence
# can become master despite an instance with higher priority sending adverts.
# This option specifies a delay in seconds before vrrp instances start up after
# keepalived starts,
vrrp_startup_delay 5.5
# The following will cause logging of receipt of VRRP adverts for VRIDs not configured
# on the interface on which they are received.
log_unknown_vrids
# Specify random seed for ${_RANDOM}, to make configurations repeatable (default
# is to use a seed based on the time, so that each time a different configuration
# will be generated).
random_seed UNSIGNED_INT
# reload_time_file allows a reload of keepalived to be scheduled in the future. This is
# particularly useful if there is a master keepalived and one or more backup keepalived
# instances and the new configuration is incompatible with the previous configuration,
# e.g. adding or removing VIPs which would cause adverts to be rejected.
# All the instances can be scheduled to reload at the same time, thereby ensuring that
# no mismatching adverts are received by the backup instances.
# The configuration specifies a file which keepalived will monitor. The first line of
# the file must contain a valid time or date/time exactly in the formats specified below.
# When keepalived starts up, it reads the file if it exists, and schedules a reload at
# the specified time. If the file does not exist, then when it is subsequently created
# a reload will be scheduled. If the file is updated, the reload time will be modified
# accordingly. If the file is deleted, the reload is cancelled.
# Normally when the reload occurs the specified file is deleted, since the reload has
# been done; if the file included a date then the reload will be in the past and so
# ignored. However, if there is no date, then if the file were reread following the
# reload, a reload would be scheduled for 24 hours time. In order to stop this, the
# file is deleted (unlinked) by default. If reload_repeat is specified, then the
# file is not deleted, and if the file contains a time only with no date, then
# keepalived will keep reloading at that time every day until the file is removed or
# modified.
# If the directory containing the file does not exist at startup/reload, or if the
# directory is removed or renamed, then no future scheduled reloads will occur until
# a manual (SIGHUP) reload is done or keepalived restarts.
# The permitted formats of the entry in the timer file are precisely:
# HH:MM:SS
# YY-MM-DD HH:MM:SS
# YYYY-MM-DD HH:MM:SS
# each with an optional 'Z' at the end.
# There must be no leading or trailing whitespace, and only one space between the date
# and the time.
# If there is a 'Z' at the end of the time, the time is parsed as UTC, otherwise the
# time is the localtime for the environment in which keepalived is running. If the
# systems which are being reloaded are in different timezones, it is probably safer to
# use UTC.
# If using local time with daylight savings, beware that some times don't exist and
# some times are duplicated and hence ambiguous.
reload_time_file ABSOLUTE-PATHNAME-OF-FILE
reload_repeat
}
Linkbeat interfaces
The linkbeat_interfaces block allows specifying which interfaces should
use polling via MII, Ethtool or ioctl status rather than rely on
netlink status updates. This allows more granular control of global
definition linkbeat_use_polling.
This option is preferred over the deprecated use of
linkbeat_use_polling in a vrrp_instance block, since
the latter only allows using linkbeat on the interface of the
vrrp_instance itself, whereas track_interface and
virtual_ipaddresses and virtual_iproutes may require monitoring other
interfaces, which may need to use linkbeat polling.
The default polling type to use is MII, unless that isn't supported in
which case ETHTOOL is used, and if that isn't supported then ioctl
polling. The preferred type of polling to use can be specified with MII
or ETHTOOL or IOCTL after the interface name, but if that type isn't
supported, a supported type will be used.
The syntax for linkbeat_interfaces is:
linkbeat_interfaces {
eth2
enp2s0 ETHTOOL
}
Static track groups
Static track groups are used to allow vrrp instances to track static
addresses, routes and rules. If a static address/route/rule specifies a
track group, then if the address/route/rule is deleted and cannot be
restored, the vrrp instance will transition to fault state.
The syntax for a track group is:
track_group GROUP1 {
group {
VI_1
VI_2
}
}
Static routes/addresses/rules
Keepalived can configure static addresses, routes, and rules. These
addresses are NOT moved by vrrpd, they stay on the
machine. If you already have IPs and routes on your machines and your
machines can ping each other, you don't need this section. The syntax
for rules and routes is that same as for ip rule add/ip route add
(except shorted option names aren't supported due to ambiguities). The
track_group specification refers to a named track_group which lists the
vrrp instances which will track the address, i.e. if the address is
deleted the vrrp instances will transition to backup.
NOTE: since rules without preferences can be added in different orders
due to vrrp instances transitioning from master to backup etc, rules
need to have a preference. If a preference is not specified, keepalived
will assign one, but it will probably not be what you want.
The syntax is the same for virtual addresses and virtual routes. If no
dev element is specified, it defaults to default_interface (default
eth0). Note: the broadcast address may be specified as '-' or '+' to
clear or set the host bits of the address.
If a route or rule could apply to either IPv4 or IPv6 it will default
to IPv4. To force a route/rule to be IPv6, add the keyword "inet6".
static_ipaddress {
<IPADDR>[/<MASK>] [brd <IPADDR>] [dev <STRING>] [scope <SCOPE>]
[label <LABEL>] [peer <IPADDR>] [home]
[-nodad] [mngtmpaddr] [noprefixroute]
[autojoin] [track_group GROUP] [preferred_lft nn|forever]
192.168.1.1/24 dev eth0 scope global
...
}
static_routes {
192.168.2.0/24 via 192.168.1.100 dev eth0 track_group GROUP1
192.168.100.0/24 table 6909 nexthop via 192.168.101.1 dev wlan0
onlink weight 1 nexthop via 192.168.101.2
dev wlan0 onlink weight 2
192.168.200.0/24 dev p33p1.2 table 6909 tos 0x04 protocol bird
scope link priority 12 mtu 1000 hoplimit 100
advmss 101 rtt 102 rttvar 103 reordering 104
window 105 cwnd 106 ssthresh lock 107 realms
PQA/0x14 rto_min 108 initcwnd 109 initrwnd 110
features ecn
2001:470:69e9:1:2::4 dev p33p1.2 table 6909 tos 0x04 protocol
bird scope link priority 12 mtu 1000
hoplimit 100 advmss 101 rtt 102 rttvar 103
reordering 104 window 105 cwnd 106 ssthresh
lock 107 rto_min 108 initcwnd 109
initrwnd 110 features ecn fastopen_no_cookie 1
...
}
static_rules {
from 192.168.2.0/24 table 1 track_group GROUP1
to 192.168.2.0/24 table 1
from 192.168.28.0/24 to 192.168.29.0/26 table small iif p33p1
oif wlan0 tos 22 fwmark 24/12
preference 39 realms 30/20 goto 40
to 1:2:3:4:5:6:7:0/112 from 7:6:5:4:3:2::/96 table 6908
uidrange 10000-19999
to 1:2:3:4:6:6:7:0/112 from 8:6:5:4:3:2::/96 l3mdev protocol 12
ip_proto UDP sport 10-20 dport 20-30
...
}
Track files
Adds a file to be monitored. The file will be read whenever it is modi-
fied. The value in the file will be recorded for all VRRP instances,
sync groups and real servers which monitor it. Note that the file will
only be read if at least one VRRP instance, sync group or real server
monitors it.
A value will be read as a number in text from the file. If the weight
configured against the track_file is 0, a non-zero value in the file
will be treated as a failure status, and a zero value will be treated
as an OK status, otherwise the value will be multiplied by the weight
configured in the track_file statement.
For VRRP instances, if the result is less than -253 anything monitoring
the script will transition to the fault state (the weight can be 254 to
allow for a negative value being read from the file).
If the vrrp instance or sync group is not the address owner and the
result is between -253 and 253, the result will be added to the initial
priority of the VRRP instance (a negative value will reduce the prior-
ity), although the effective priority will be limited to the range
[1,254]. Likewise for real servers.
If a vrrp instance using a track_file is a member of a sync group,
unless sync_group_tracking_weight is set on the group weight 0 must be
set. Likewise, if the vrrp instance is the address owner, weight 0
must also be set.
For real servers monitoring the file, the limits of values read from
the track file are 2147483646 to -2147483647. The value, once multi-
plied by the weight, will be added to the real server's IPVS weight.
NOTE: weights for track_file for real servers are not fully implemented
yet. In particular allowing weight 0, handling negative calculated val-
ues and reloading.
The syntax for track file is:
track_file <STRING> {
# vrrp_track_file is a deprecated synonym
# file to track (weight defaults to 1)
file <QUOTED_STRING>
# optional default weight
weight <-2147483647..2147483647> [reverse]
# create the file and/or initialise the value
# This causes VALUE (default 0) to be written to
# the specified file at startup if the file doesn't
# exist, unless overwrite is specified in which case
# any existing file contents will be overwritten with
# the specified value.
init_file [VALUE] [overwrite]
}
VRRP track processes
The configuration block looks like:
vrrp_track_process <STRING> {
# process to monitor (with optional parameters)
# A quoted string is treated as a single element, so if the first item
# after the process keyword is quoted, that will be the command name.
# For example:
# process "/tmp/a b" param1 "param 2"
# would mean a process named '/tmp/a b' (quotes removed) with 2 parameters
# 'param1' and 'param 2'.
process <STRING>|<QUOTED_STRING> [<STRING>|<QUOTED_STRING> ...]
# If matching parameters, this specifies a partial match (i.e. the first
# n parameters match exactly), or an initial match, i.e. the last
# parameter may be longer that the parameter configured.
# To specify that a command must have no parameters, don't specify
# any parameters, but specify param_match.
param_match {
initial|partial}
# default weight (default is 1). For description of reverse, see track_process.
# 'weight 0 reverse' will cause the vrrp instance to be down when the
# quorum is up, and vice versa.
weight <-254..254> [reverse]
# minimum number of processes for success
quorum NUM
# maximum number of processes for success. For example, setting
# this to 1 would cause a failure if two instances of the process
# were running (but beware forks - see fork_delay below).
# Setting this to 0 would mean failure if the matching process were
# running at all.
quorum_max NUM
# time to delay after process quorum gained after fork before
# consider process up (in fractions of second)
# This is to avoid up/down bounce for fork/exec
fork_delay SECS
# time to delay after process quorum lost before
# consider process down (in fractions of second)
# This is to avoid down/up bounce after terminate/parent refork.
terminate_delay SECS
# this sets fork_delay and terminate_delay
delay SECS
# Normally process string is matched against the process name,
# as shown on the Name: line in /proc/PID/status, unless
# parameters are specified.
# This option forces matching the full command line
full_command
}
To avoid having to frequently run a track_script to monitor the exis-
tance of processes (often haproxy or nginx), vrrp_track_process can
monitor whether other processes are running.
One difference from pgrep is track_process doesn't do a regular expres-
sion match of the command string, but does an exact match. 'pgrep ssh'
will match an sshd process, this track_process will not (it is equiva-
lent to pgrep "^ssh$").
If full_command is used (equivalent to pgrep -f), /proc/PID/cmdline is
used, but any updates to cmdline will not be detected (a process
shouldn't normally change it, although it is possible with great care,
for example systemd).
Prior to Linux v3.2 track_process will not support detection of changes
to a process name, since the kernel did not notify changes of process
name prior to 3.2. Most processes do not change their process name,
but, for example, firefox forks processes that change their process
name to "Web Content". The process name referred to here is the con-
tents of /proc/PID/comm.
Quorum is the number of matching processes that must be run for an OK
status.
Delay might be useful if it anticipated that a process may be reloaded
(stopped and restarted), and it isn't desired to down and up a vrrp
instance.
A positive weight means that an OK status will add <weight> to
the priority of all VRRP instances which monitor it. On the opposite, a
negative weight will be subtracted from the initial priority in case of
insufficient processes.
If the vrrp instance or sync group is not the address owner and the
result is between -253 and 253, the result will be added to the initial
priority of the VRRP instance (a negative value will reduce the prior-
ity), although the effective priority will be limited to the range
[1,254].
If a vrrp instance using a track_process is a member of a sync group,
unless sync_group_tracking_weight is set on the group weight 0 must be
set. Likewise, if the vrrp instance is the address owner, weight 0
must also be set.
Rational for not using pgrep/pidof/killall and the likes:
Every time pgrep or its equivalent is run, it iterates though the
/proc/[1-9][0-9]* directories, and opens the status and cmdline pseudo
files in each directory. The cmdline pseudo file is mapped to the
process's address space, and so if that part of the process is swapped
out, it will have to be fetched from the swap space. pgrep etc also
include zombie processes whereas keepalived does not, since they aren't
running.
This implementation only iterates though /proc/[1-9][0-9]*/ directories
at start up, and it won't even read the cmdline pseudo files if
'full_command' is not specified for any of the vrrp_track_process
entries. After startup, it uses the process_events kernel <->
userspace connector to receive notification of process changes. If
full_command is specified for any track_process instance, the cmdline
pseudo file will have to be read upon notification of the creation of
the new process, but at that time it is very unlikely that it will have
already been swapped out.
On a busy system with a high number of process creations/terminations,
using a track_script with pgrep/pidof/killall may be more efficient,
although those processes are inefficient compared to the minimum that
keepalived needs.
Using pgrep etc on a system that is swapping can have a significant
detrimental impact on the performance of the system, due to having to
fetch swapped memory from the swap space, thereby causing additional
swapping.
BFD CONFIGURATION
This is an implementation of RFC5880 (Bidirectional forwarding detec-
tion), and this can be configured to work between 2 keepalived
instances, but using unweighted track_bfds between a master/backup pair
of VRRP instances means that the VRRP instance will only be able to
come up if both VRRP instance are running, which somewhat defeats the
purpose of VRRP.
This implementation has been tested with OpenBFDD (available at
https://github.com/dyninc/OpenBFDD).
The syntax for bfd instance is :
bfd_instance <STRING> {
# BFD Neighbor IP (synonym neighbour_ip)
neighbor_ip <IP ADDRESS>
# Source IP to use (optional, except in order to ensure that the
# local port is valid, it is required)
source_ip <IP ADDRESS>
# Required min RX interval, in ms
# (default is 10 ms)
min_rx <INTEGER>
# Desired min TX interval, in ms
# (default is 10 ms)
min_tx <INTEGER>
# Desired idle TX interval, in ms
# (default is 1000 ms)
idle_tx <INTEGER>
# Number of missed packets after
# which the session is declared down
# (default is 5)
multiplier <INTEGER>
# Operate in passive mode (default is active)
passive
# outgoing IPv4 ttl to use (default 255)
ttl <INTEGER>
# outgoing IPv6 hoplimit to use (default 64)
hoplimit <INTEGER>
# maximum reduction of ttl/hoplimit
# in received packet (default 0)
# (255 disables hop count checking)
max_hops <INTEGER>
# Default tracking weight
# Normally, positive weights are added to the vrrp instance priority when
# the bfd instance is up, negative weights reduce the priority when it is down.
# However, if reverse is specified, the priority is decreased when up and
# increased when down. 'weight 0 reverse' will cause the vrrp instance to be down
# when the bfd instance is up, and vice versa.
weight <-253:253> [reverse]
# Normally bfd event notifications are sent to both the VRRP and checker processes.
# Specifying vrrp or checker will cause event notifications for this bfd_instance
# only to be sent to the specified process
vrrp
checker
}
VRRPD CONFIGURATION
contains subblocks of VRRP script(s), VRRP synchronization
group(s), VRRP gratuitous ARP and unsolicited neighbour advert delay
group(s) and VRRP instance(s)
VRRP script(s)
The script will be executed periodically, every <interval> sec-
onds. Its exit code will be recorded for all VRRP instances which moni-
tor it. Note that the script will only be executed if at least one
VRRP instance monitors it.
The default weight equals 0, which means that any VRRP instance moni-
toring the script will transition to the fault state after <fall>
consecutive failures of the script. After that, <rise> consecu-
tive successes will cause VRRP instances to leave the fault state,
unless they are also in the fault state due to other scripts or inter-
faces that they are tracking.
A positive weight means that <rise> successes will add
<weight> to the priority of all VRRP instances which monitor it.
On the opposite, a negative weight will be subtracted from the initial
priority in case of <fall> failures.
The syntax for the vrrp script is:
# Adds a script to be executed periodically. Its exit code will be
# recorded for all VRRP instances and sync groups which are monitoring it.
vrrp_script <SCRIPT_NAME> {
# path of the script to execute
script <STRING>|<QUOTED-STRING>
# seconds between script invocations, (default: 1 second)
interval <INTEGER>
# seconds after which script is considered to have failed
timeout <INTEGER>
# adjust priority by this weight, (default: 0)
# For description of reverse, see track_script.
# 'weight 0 reverse' will cause the vrrp instance to be down when the
# script is up, and vice versa.
weight <INTEGER:-253..253> [reverse]
# required number of successes for OK transition
rise <INTEGER>
# required number of successes for KO transition
fall <INTEGER>
# user/group names to run script under.
# group default to group of user
user USERNAME [GROUPNAME]
# assume script initially is in failed state
init_fail
}
VRRP synchronization group(s)
VRRP Sync Group is an extension to VRRP protocol. The main goal is to
define a bundle of VRRP instance to get synchronized together so that
transition of one instance will be reflected to others group members.
In addition there is an enhanced notify feature for fine state transi-
tion catching.
You can also define multiple track policy in order to force state tran-
sition according to a third party event such as interface, scripts,
file, BFD.
Important: for a SYNC group to run reliably, it is
vital that all instances in the group are MASTER or that they are all
either BACKUP or FAULT. A situation with half instances having higher
priority on machine A half others with higher priority on machine B
will lead to constant re-elections. For this reason, when instances are
grouped, any track scripts/files configured against member VRRP
instances will have their tracking weights automatically set to zero,
in order to avoid inconsistent priorities across instances.
The syntax for vrrp_sync_group is :
vrrp_sync_group <STRING> {
group {
# name of the vrrp_instance (see below)
# Set of VRRP_Instance string
<STRING>
<STRING>
...
}
# Synchronization group tracking interface, script, file & bfd will
# update the status/priority of all VRRP instances which are members
# of the sync group.
# 'weight 0 reverse' will cause the vrrp instance to be down when the
# interface is up, and vice versa.
track_interface {
eth0
eth1
eth2 weight <-253..253> [reverse]
...
}
# add a tracking script to the sync group (<SCRIPT_NAME> is the name
# of the vrrp_script entry) go to FAULT state if any of these go down
# if unweighted.
# reverse causes the direction of the adjustment of the priority to be reversed.
track_script {
<SCRIPT_NAME>
<SCRIPT_NAME> weight <-253..253> [reverse|no_reverse]
}
# Files whose state we monitor, value is added to effective priority.
# <STRING> is the name of a track_file
# weight defaults to weight configured in track_file
track_file {
<STRING>
<STRING> weight <-254..254> [reverse|noreverse]
...
}
# Process to monitor, weight is added to effective priority.
# <STRING> is the name of a vrrp_track_process
# weight defaults to weight configured in vrrp_track_process.
# See vrrp_instance track_process for description of weight.
track_process {
<STRING>
<STRING> weight <-254..254> [reverse|noreverse]
...
}
# BFD instances we monitor, value is added to effective priority.
# <STRING> is the name of a BFD instance
track_bfd {
<STRING>
<STRING>
<STRING> weight <INTEGER: -253..253> [reverse|noreverse]
...
}
# notify scripts and alerts are optional
#
# filenames of scripts to run on transitions can be unquoted (if
# just filename) or quoted (if it has parameters)
# The username and groupname specify the user and group
# under which the scripts should be run. If username is
# specified, the group defaults to the group of the user.
# If username is not specified, they default to the
# global script_user and script_group
# to MASTER transition
notify_master /path/to_master.sh [username [groupname]]
# to BACKUP transition
notify_backup /path/to_backup.sh [username [groupname]]
# FAULT transition
notify_fault "/path/fault.sh VG_1" [username [groupname]]
# executed when stopping vrrp
notify_stop <STRING>|<QUOTED-STRING> [username [groupname]]
# notify_deleted causes DELETED to be sent to notifies rather
# than the default FAULT after a vrrp instance is deleted during a
# reload. If a script is specified, that script will be executed
# as well.
notify_deleted [<STRING>|<QUOTED-STRING> [username [groupname]]]
# for ANY state transition.
# "notify" script is called AFTER the notify_* script(s) and
# is executed with 4 additional arguments after the configured
# arguments provided by Keepalived:
# $(n-3) = "GROUP"|"INSTANCE"
# $(n-2) = name of the group or instance
# $(n-1) = target state of transition (stop only applies to instances)
# ("MASTER"|"BACKUP"|"FAULT"|"STOP"|"DELETED")
# $(n) = priority value
# $(n-3) and $(n-1) are ALWAYS sent in uppercase, and the possible
# strings sent are the same ones listed above
# ("GROUP"/"INSTANCE", "MASTER"/"BACKUP"/"FAULT"/"STOP"/"DELETED")
# (note: STOP and DELETED are only applicable to instances)
notify <STRING>|<QUOTED-STRING> [username [groupname]]
# The notify fifo output is the same as the last 4 parameters for the "notify"
# script, with the addition of "MASTER_RX_LOWER_PRI" instead of state for an
# instance, and also "MASTER_PRIORITY" and "BACKUP_PRIORITY" if the priority
# changes and notify_priority_changes is configured.
# MASTER_RX_LOWER_PRI is used if a master needs to set some external state, such
# as setting a secondary IP address when using Amazon AWS; if another keepalived
# has transitioned to master due to a communications break, the lower priority
# instance will have taken over the secondary IP address, and the proper master
# needs to be able to restore it.
# Send FIFO notifies for vrrp priority changes
notify_priority_changes <BOOL>
# Send email notification during state transition,
# using addresses in global_defs above (default no,
# unless global smtp_alert/smtp_alert_vrrp set)
smtp_alert <BOOL>
# DEPRECATED. Use track_interface, track_script and
# track_file on vrrp_sync_groups instead.
global_tracking
# allow sync groups to use differing weights.
# This probably WON'T WORK, but is a replacement for
# global_tracking in case different weights were used
# across different vrrp instances in the same sync group.
sync_group_tracking_weight
}
VRRP gratuitous ARP and unsolicited neighbour advert delay group(s)
specifies the setting of delays between sending gratuitous ARPs and
unsolicited neighbour advertisements. This is intended for when an
upstream switch is unable to handle being flooded with ARPs/NAs.
Use interface when the limits apply on the single physical interface.
Use interfaces when a group of interfaces are linked to the same switch
and the limits apply to the switch as a whole.
Note: Only one of interface or interfaces should be
used per block.
If the global vrrp_garp_interval and/or vrrp_gna_interval are set, any
interfaces that aren't specified in a garp_group will inherit the
global settings.
The syntax for garp_group is :
garp_group {
# Sets the interval between Gratuitous ARP (in seconds, resolution microseconds)
garp_interval <DECIMAL>
# Sets the default interval between unsolicited NA (in seconds, resolution microseconds)
gna_interval <DECIMAL>
# The physical interface to which the intervals apply
interface <STRING>
# A list of interfaces accross which the delays are aggregated.
interfaces {
<STRING>
<STRING>
...
}
}
VRRP instance(s)
A VRRP Instance is the VRRP protocol key feature. It defines and con-
figures VRRP behaviour to run on a specific interface. Each VRRP
Instances are related to a uniq interface.
The syntax for vrrp_instance is :
vrrp_instance <STRING> {
# Initial state, MASTER|BACKUP
# As soon as the other machine(s) come up,
# an election will be held and the machine
# with the highest priority will become MASTER.
# So the entry here doesn't matter a whole lot.
state MASTER
# interface for inside_network, bound by vrrp.
# Note: if using unicasting, the interface can be omitted as long
# as the unicast addresses are not IPv6 link local addresses (this is
# necessary, for example, if using asymmetric routing).
# If the interface is omitted, then all VIPs and eVIPs should specify
# the interface they are to be configured on, otherwise they will be
# added to the default interface.
interface eth0
# Use VRRP Virtual MAC.
# NOTE: If sysctl net.ipv4.conf.all.rp_filter is set,
# and this vrrp_instance is an IPv4 instance, using
# this option will cause the individual interfaces to be
# updated to the greater of their current setting, and
# all.rp_filter, as will default.rp_filter, and all.rp_filter
# will be set to 0.
# The original settings are restored on termination.
use_vmac [<VMAC_INTERFACE>]
# Send/Recv VRRP messages from base interface instead of
# VMAC interface
vmac_xmit_base
# Use IPVLAN interface. keepalived will create a mode L2
# ipvlan interface on top of the specified interface.
# For IPv4 instances, an IP address is required, for IPv6
# the address is optional, in which case the link local
# address will be used.
# The mode flags default to bridge. NOTE: the mode flags must be the
# same for all ipvlans on the same underlying interface.
# It is safer to configure an interface name, in case keepalived crashes
# and restarts, in which case it can more reliably find a previously
# created interface.
use_ipvlan [<INTERFACE_NAME>] [IP_ADDRESS] [bridge|private|vepa]
# force instance to use IPv6 (this option is deprecated since
# the virtual ip addresses determine whether IPv4 or IPv6 is used).
native_ipv6
# Ignore VRRP interface faults (default unset)
dont_track_primary
# optional, monitor these as well.
# go to FAULT state if any of these go down if unweighted.
# When a weight is specified in track_interface, instead of setting the vrrp
# instance to the FAULT state in case of failure, its priority will be
# increased by the weight when the interface is up (for positive weights),
# or decreased by the weight's absolute value when the interface is down
# (for negative weights), unless reverse is specified, in which case the
# direction of adjustment of the priority is reversed.
# The weight must be comprised between -253 and +253 inclusive.
# 0 is the default behaviour which means that a failure implies a
# FAULT state. The common practice is to use positive weights to count a
# limited number of good services so that the server with the highest count
# becomes master. Negative weights are better to count unexpected failures
# among a high number of interfaces, as it will not saturate even with high
# number of interfaces. Use reverse to increase priority if an interfaces is down
track_interface {
eth0
eth1
eth2 weight <-253..253> [reverse]
...
}
# add a tracking script to the interface
# (<SCRIPT_NAME> is the name of the vrrp_track_script entry)
# The same principle as track_interface can be applied to track_script entries,
# except that an unspecified weight means that the default weight declared in
# the script will be used (which itself defaults to 0).
# reverse causes the direction of the adjustment of the priority to be reversed.
track_script {
<SCRIPT_NAME>
<SCRIPT_NAME> weight <-253..253> [reverse|no_reverse]
}
# Files whose state we monitor, value is added to effective priority.
# <STRING> is the name of a track_file
track_file {
<STRING>
<STRING>
<STRING> weight <-254..254> [reverse|noreverse]
...
}
# Positive weights are added/subtracted when the process is running,
# negative weights are subtracted/added when the not running.
# If reverse is specified, the addition/subtraction is reversed.
# <STRING> is the name of a vrrp_track_process
# weight defaults to weight configured in vrrp_track_process
track_process {
<STRING>
<STRING> weight <-254..254> [reverse|noreverse]
...
}
# BFD instances we monitor, value is added to effective priority,
# unless reverse is specified, when the value is subtracted.
# Positive weights are add/subtracted when the bfd instance is up,
# negative weights are subtracted/added when the bfd instance is down.
# <STRING> is the name of a BFD instance
track_bfd {
<STRING>
<STRING>
<STRING> weight <INTEGER: -253..253> [reverse|noreverse]
...
}
# default IP for binding vrrpd is the primary IP
# on interface. If you want to hide the location of vrrpd,
# use this IP as src_addr for multicast or unicast vrrp
# packets. (since it's multicast, vrrpd will get the reply
# packet no matter what src_addr is used).
# optional
mcast_src_ip <IPADDR>
unicast_src_ip <IPADDR>
# if the configured src_ip doesn't exist or is removed put the
# instance into fault state
track_src_ip
# VRRP version to run on interface
# default is global parameter vrrp_version, but IPv6 instances will
# always use version 3.
version <2 or 3>
# The following enables checking that when in unicast mode, the
# source address of a VRRP packet is one of our unicast peers.
check_unicast_src
# Do not send VRRP adverts over a VRRP multicast group.
# Instead it sends adverts to the following list of
# ip addresses using unicast. It can be cool to use
# the VRRP FSM and features in a networking
# environment where multicast is not supported!
# IP addresses specified can be IPv4 as well as IPv6.
# If min_ttl and/or max_ttl are specified, the TTL/hop limit
# of any received packet is checked against the specified
# TTL range, and is discarded if it is outside the range.
# Specifying min_ttl or max_ttl turns on check_unicast_src.
unicast_peer {
<IPADDR> [min_ttl {
0..255}] [max_ttl {
0..255}]
...
}
# Specify the unicast TTL/HLIM for sending unicast adverts
unicast_ttl {
0..255}
# The checksum calculation when using VRRPv3 changed after v1.3.6.
# Setting this flag forces the old checksum algorithm to be used
# to maintain backward compatibility, although keepalived will
# attempt to maintain compatibility anyway if it sees an old
# version checksum. Specifying never will turn off auto detection
# of old checksums. [This option may not be enabled - check output
# of `keepalived -v` for OLD_CHKSUM_COMPAT.]
old_unicast_checksum [never]
# interface specific settings, same as global parameters.
# default to global parameters
garp_master_delay 10
garp_master_repeat 1
garp_lower_prio_delay 10
garp_lower_prio_repeat 1
garp_master_refresh 60
garp_master_refresh_repeat 2
garp_interval 100
gna_interval 100
# If a lower priority advert is received, don't send another advert.
# This causes adherence to the RFCs (defaults to global
# vrrp_lower_priority_dont_send_advert).
lower_prio_no_advert [<BOOL>]
# If we are master and receive a higher priority advert, send an advert
# (which will be lower priority than the other master), before we transition
# to backup. This means that if the other master has garp_lower_prio_repeat
# set, it will resend garp messages. This is to get around the problem of
# their having been two simultaneous masters, and the last GARP
# messages seen were from us.
higher_prio_send_advert [<BOOL>]
# arbitrary unique number from 1 to 255
# used to differentiate multiple instances of vrrpd
# running on the same NIC (and hence same socket).
virtual_router_id 51
# for electing MASTER, highest priority wins.
# to be MASTER, make this 50 more than on other machines.
priority 100
# VRRP Advert interval in seconds (e.g. 0.92) (use default)
advert_int 1
# Note: authentication was removed from the VRRPv2 specification by
# RFC3768 in 2004.
# Use of this option is non-compliant and can cause problems; avoid
# using if possible, except when using unicast, where it can be helpful.
authentication {
# PASS|AH
# PASS - Simple password (suggested)
# AH - IPSEC (not recommended))
auth_type PASS
# Password for accessing vrrpd.
# should be the same on all machines.
# Only the first eight (8) characters are used.
auth_pass 1234
}
# addresses add|del on change to MASTER, to BACKUP.
# With the same entries on other machines,
# the opposite transition will be occurring.
# For virtual_ipaddress, virtual_ipaddress_excluded,
# virtual_routes and virtual_rules most of the options
# match the options of the command ip address/route/rule add.
# The track_group option only applies to static addresses/routes/rules.
# no_track is specific to keepalived and means that the
# vrrp_instance will not transition out of master state
# if the address/route/rule is deleted and the address/route/rule
# will not be reinstated until the vrrp instance next transitions
# to master.
# <LABEL>: is optional and creates a name for the alias.
For compatibility with "ifconfig", it should
be of the form <realdev>:<anytext>, for example
eth0:1 for an alias on eth0.
# <SCOPE>: ("site"|"link"|"host"|"nowhere"|"global")
# preferred_lft is set to 0 to deprecate IPv6 addresses (this is the
# default if the address mask is /128). Use "preferred_lft forever"
# to specify that a /128 address should not be deprecated.
virtual_ipaddress {
<IPADDR>[/<MASK>] [brd <IPADDR>] [dev <STRING>] [scope <SCOPE>]
[label <LABEL>] [peer <IPADDR>] [home]
[-nodad] [mngtmpaddr] [noprefixroute]
[autojoin] [no_track] [preferred_lft nn|forever]
192.168.200.17/24 dev eth1
192.168.200.18/24 dev eth2 label eth2:1
}
# VRRP IP excluded from VRRP optional.
# For cases with large numbers (eg 200) of IPs
# on the same interface. To decrease the number
# of addresses sent in adverts, you can exclude
# most IPs from adverts.
# The IPs are add|del as for virtual_ipaddress.
# Can also be used if you want to be able to add
# a mixture of IPv4 and IPv6 addresses, since all
# addresses in virtual_ipaddress must be of the
# same family.
virtual_ipaddress_excluded {
<IPADDR>[/<MASK>] [brd <IPADDR>] [dev <STRING>] [scope <SCOPE>]
[label <LABEL>] [peer <IPADDR>] [home]
[-nodad] [mngtmpaddr] [noprefixroute]
[autojoin] [no_track]
<IPADDR>[/<MASK>] ...
...
}
# Set the promote_secondaries flag on the interface to stop other
# addresses in the same CIDR being removed when 1 of them is removed
# For example if 10.1.1.2/24 and 10.1.1.3/24 are both configured on an
# interface, and one is removed, unless promote_secondaries is set on
# the interface the other address will also be removed.
promote_secondaries
# routes add|del when changing to MASTER, to BACKUP.
# See static_routes for more details
virtual_routes {
# src <IPADDR> [to] <IPADDR>/<MASK> via|gw <IPADDR>
# [or <IPADDR>] dev <STRING> scope <SCOPE> table <TABLE>
src 192.168.100.1 to 192.168.109.0/24 via 192.168.200.254 dev eth1
192.168.110.0/24 via 192.168.200.254 dev eth1
192.168.111.0/24 dev eth2 no_track
192.168.112.0/24 via 192.168.100.254
192.168.113.0/24 via 192.168.200.254 or 192.168.100.254 dev eth1
blackhole 192.168.114.0/24
0.0.0.0/0 gw 192.168.0.1 table 100 # To set a default gateway into table 100.
}
# rules add|del when changing to MASTER, to BACKUP
# See static_rules for more details
virtual_rules {
from 192.168.2.0/24 table 1
to 192.168.2.0/24 table 1 no_track
}
# VRRPv3 has an Accept Mode to allow the virtual router when not the
# address owner to receive packets addressed to a VIP. This is the default
# setting unless strict mode is set. As an extension, this also works for
# VRRPv2 (RFC 3768 doesn't define an accept mode).
# --
# Accept packets to non address-owner
accept
# Drop packets to non address-owner.
no_accept
# A higher priority VRRP instance will normally preempt a lower priority instance
# when it comes online. "nopreempt" stops the higher priority machine taking
# over the master role, and allows the lower priority machine to remain as
# master.
# NOTE: For this to work, the initial state must not be MASTER.
# --
nopreempt
# for backwards compatibility
preempt
# Seconds after startup or seeing a lower priority master until preemption
# (if not disabled by "nopreempt").
# Range: 0 (default) to 1000 (e.g. 4.12)
# NOTE: For this to work, the initial state must not be MASTER.
preempt_delay 300 # waits 5 minutes
# See description of global vrrp_skip_check_adv_addr, which
# sets the default value. Defaults to vrrp_skip_check_adv_addr
skip_check_adv_addr [on|off|true|false|yes|no]
# See description of global vrrp_strict
# If vrrp_strict is not specified, it takes the value of vrrp_strict
# If strict_mode without a parameter is specified, it defaults to on
strict_mode [on|off|true|false|yes|no]
# Debug level, not implemented yet.
# LEVEL is a number in the range 0 to 4
debug <LEVEL>
# notify scripts, alert as above
notify_master <STRING>|<QUOTED-STRING> [username [groupname]]
notify_backup <STRING>|<QUOTED-STRING> [username [groupname]]
notify_fault <STRING>|<QUOTED-STRING> [username [groupname]]
# executed when stopping vrrp
notify_stop <STRING>|<QUOTED-STRING> [username [groupname]]
notify <STRING>|<QUOTED-STRING> [username [groupname]]
# The notify_master_rx_lower_pri script is executed if a master
# receives an advert with priority lower than the master's priority.
notify_master_rx_lower_pri <STRING>|<QUOTED-STRING> [username [groupname]]
# Send vrrp instance priority notifications on notify FIFOs.
notify_priority_changes <BOOL>
# Send SMTP alerts
smtp_alert <BOOL>
# Set socket receive buffer size (see global_defs
# vrrp_rx_bufs_policy for explanation)
kernel_rx_buf_size
# Set use of linkbeat for the interface of this VRRP instance. This option is
# deprecated - use linkbeat_interfaces block instead.
linkbeat_use_polling
}
LVS CONFIGURATION
contains subblocks of Virtual server group(s) and
Virtual server(s)
The subblocks contain arguments for configuring Linux IPVS (LVS) fea-
ture. Knowledge of ipvsadm(8) will be helpful here. Configuring LVS is
achieved by defining virtual server groups, virtual servers and option-
ally SSL configuration. Every virtual server defines a set of real
servers, you can attach healthcheckers to each real server. Keepalived
will then lead LVS operation by dynamically maintaining topology.
For details of what configuration combinations are valid, see the
ipvsadm(8) man page.
Note: Where an option can be configured for a virtual
server, real server, and possibly checker, the virtual server setting
is the default for real servers, and the real server setting is the
default for checkers.
Note: Tunnelled real/sorry servers can differ from the
address family of the virtual server and non tunnelled real/sorry
servers, which all have to be the same. If a virtual server uses a
fwmark, and all the real/sorry servers are tunnelled, the address fam-
ily of the virtual server will be the same as the address family of the
real/sorry servers if they are all the same, otherwise it will default
to IPv4 (use ip_family inet6 to override this).
Note: The port for the virtual server can only be
omitted if the virtual service is persistent.
Virtual server group(s)
This feature offers a way to simplify your configuration by factorizing
virtual server definitions. If you need to define a bunch of virtual
servers with exactly the same real server topology then this feature
will make your configuration much more readable and will optimize
healthchecking task by only spawning one healthchecking where multiple
virtual server declaration will spawn a dedicated healthchecker for
every real server which will waste system resources.
Any combination of IP addresses, IP address ranges and firewall marks
can be used, provided that the family of the IP addresses of the vir-
tual server group match the IP address family of all the real servers
of any virtual server using the virtual server group. The one exception
to this is that the virtual server group can be configured with both
IPv4 and IPv6 addresses and fwmarks provided that all the real servers
(and sorry servers) of all virtual servers using the virtual server
group use tunnel forwarding; if fwmarks are specified in this case, the
address family must be specified. Use of this option is intended for
very large LVSs.
The syntax for virtual_server_group is :
virtual_server_group <STRING> {
# Virtual IP Address and Port
<IPADDR> [<PORT>]
<IPADDR> [<PORT>]
...
# <IPADDR RANGE> has the form
# XXX.YYY.ZZZ.WWW-VVV eg 192.168.200.1-10
# range includes both .1 and .10 address
<IPADDR RANGE> [<PORT>] # VIP range [VPORT]
<IPADDR RANGE> [<PORT>]
...
# Firewall Mark (fwmark)
# inet/inet6 should only be specified for virtual server groups
# where all real servers of the virtual servers are tunnelled.
fwmark <INTEGER>
fwmark <INTEGER> [inet|inet6]
...
}
Virtual server(s)
A virtual_server can be a declaration of one of <IPADDR>
[<PORT>] , fwmark <INTEGER> or
group <STRING>
The syntax for virtual_server is :
virtual_server <IPADDR> [<PORT>] |
virtual_server fwmark <INTEGER> |
virtual_server group <STRING> {
# LVS scheduler
lvs_sched rr|wrr|lc|wlc|lblc|sh|mh|dh|fo|ovf|lblcr|sed|nq
# Enable hashed entry
hashed
# Enable flag-1 for scheduler (-b flag-1 in ipvsadm)
flag-1
# Enable flag-2 for scheduler (-b flag-2 in ipvsadm)
flag-2
# Enable flag-3 for scheduler (-b flag-3 in ipvsadm)
flag-3
# Enable sh-port for sh scheduler (-b sh-port in ipvsadm)
sh-port
# Enable sh-fallback for sh scheduler (-b sh-fallback in ipvsadm)
sh-fallback
# Enable mh-port for mh scheduler (-b mh-port in ipvsadm)
mh-port
# Enable mh-fallback for mh scheduler (-b mh-fallback in ipvsadm)
mh-fallback
# Enable One-Packet-Scheduling for UDP (-O in ipvsadm)
ops
# Override default LVS forwarding method (default is NAT).
# Default tunnel type is ipip. Since Linux 5.2 the GUE tunnel type can
# be specified. If using GUE, a port number is required. Since Linux 5.3
# if the tunnel type is GUE, the checksum option can also be specified.
# Since Linux 5.3, GRE tunnel type is also supported, but without the
# remcsum option.
lvs_method NAT|DR
or
lvs_method TUN [type {
ipip|gue port NUM|gre} [nocsum|csum|remcsum]]
# LVS persistence engine name (currently only sip supported)
persistence_engine <STRING>
# LVS persistence timeout in seconds, default 6 minutes
persistence_timeout [<INTEGER>]
# LVS granularity mask (-M in ipvsadm)
persistence_granularity <NETMASK>
# L4 protocol
protocol TCP|UDP|SCTP
# If VS IP address is not set,
# suspend healthchecker's activity
ha_suspend
# Send email notification during quorum up/down transition,
# using addresses in global_defs above (default no,
# unless global smtp_alert/smtp_alert_checker set)
smtp_alert <BOOL>
# Default VirtualHost string for HTTP_GET or SSL_GET
# eg virtualhost www.firewall.loc
# Overridden by virtualhost config of real server or checker
virtualhost <STRING>
# On daemon startup assume that all RSs are down
# and healthchecks failed. This helps to prevent
# false positives on startup. Alpha mode is
# disabled by default.
alpha
# On daemon shutdown consider quorum and RS
# down notifiers for execution, where appropriate.
# Omega mode is disabled by default.
omega
# Minimum total weight of all live servers in
# the pool necessary to operate VS with no
# quality regression. Defaults to 1.
quorum <INTEGER>
# Tolerate this much weight units compared to the
# nominal quorum, when considering quorum gain
# or loss. A flap dampener. Defaults to 0.
hysteresis <INTEGER>
# Script to execute when quorum is gained.
quorum_up <STRING>|<QUOTED-STRING> [username [groupname]]
# Script to execute when quorum is lost.
quorum_down <STRING>|<QUOTED-STRING> [username [groupname]]
# IP family for a fwmark service (only needed if all real servers are tunnelled
# and persistence_granularity is not specified). Defaults to inet if not specified.
ip_family inet|inet6
# setup realserver(s)
# RS to add to LVS topology when the quorum isn't achieved.
# If a sorry server is configured, all real servers will
# be brought down when the quorum is not achieved and be
# replaced with the sorry server.
sorry_server <IPADDR> [<PORT>]
# applies inhibit_on_failure behaviour to the sorry_server
sorry_server_inhibit
# Sorry server LVS forwarding method. Default is the virtual
# server's default.
# For details of tunnel type, see virtual_server details.
sorry_server_lvs_method NAT|DR
or
sorry_server_lvs_method TUN [type {
ipip|gue port NUM|gre} [nocsum|csum|remcsum]]
# Optional connection timeout in seconds.
# The default is 5 seconds
connect_timeout <TIMER>
# Retry count to make additional checks if check
# of an alive server fails. Default: 1 unless specified below
retry <INTEGER>
# delay before retry after failure
delay_before_retry <TIMER>
# Optional random delay to start the initial check
# for maximum N seconds.
# Useful to scatter multiple simultaneous
# checks to the same RS. Enabled by default, with
# the maximum at delay_loop. Specify 0 to disable
warmup <TIMER>
# delay timer for checker polling
delay_loop <TIMER>
# Set weight to 0 when healthchecker detects failure
inhibit_on_failure
# one entry for each realserver
real_server <IPADDR> [<PORT>] {
# relative weight to use, default: 1
weight <INTEGER>
# LVS forwarding method
# For details of tunnel type, see virtual_server details. The default
# setting is taken from the virtual_server's setting.
lvs_method NAT|DR
or
lvs_method TUN [type {
ipip|gue port NUM|gre} [nocsum|csum|remcsum]]
# Script to execute when healthchecker
# considers service as up.
notify_up <STRING>|<QUOTED-STRING> [username [groupname]]
# Script to execute when healthchecker
# considers service as down.
notify_down <STRING>|<QUOTED-STRING> [username [groupname]]
# maximum number of connections to server
uthreshold <INTEGER>
# minimum number of connections to server
lthreshold <INTEGER>
# Send email notification during state transition,
# using addresses in global_defs above (default yes,
# unless global smtp_alert/smtp_alert_checker set)
smtp_alert <BOOL>
# Default VirtualHost string for HTTP_GET or SSL_GET
# eg virtualhost www.firewall.loc
# Overridden by virtualhost config of a checker
virtualhost <STRING>
alpha <BOOL> # see above
connect_timeout <TIMER> # see above
retry <INTEGER> # see above
delay_before_retry <TIMER> # see above
warmup <TIMER> # see above
delay_loop <TIMER> # see above
inhibit_on_failure <BOOL> # see above
log_all_failures <BOOL> # log all failures when checker up
# healthcheckers. Can be multiple of each type
# HTTP_GET|SSL_GET|TCP_CHECK|SMTP_CHECK|DNS_CHECK|MISC_CHECK|BFD_CHECK|UDP_CHECK|PING_CHECK|FILE_CHECK
# All checkers have the following options, except MISC_CHECK which only
# has options alpha onwards, and BFD_CHECK and FILE_CHECK which have none
# of the standard options:
CHECKER_TYPE {
# ======== generic connection options
# Optional IP address to connect to.
# The default is the realserver IP
connect_ip <IPADDR>
# Optional port to connect to
# The default is the realserver port
connect_port <PORT>
# Optional address to use to
# originate the connection
bindto <IPADDR>
# Optional interface to use; needed if
# the bindto address is IPv6 link local
bind_if <IFNAME>
# Optional source port to
# originate the connection from
bind_port <PORT>
# Optional fwmark to mark all outgoing
# checker packets with
fwmark <INTEGER>
alpha <BOOL> # see above
connect_timeout <TIMER> # see above
retry <INTEGER> # see above
delay_before_retry <TIMER> # see above
warmup <TIMER> # see above
delay_loop <TIMER> # see above
}
# The following options are additional checker specific
# HTTP and SSL healthcheckers
HTTP_GET|SSL_GET {
# HTTP protocol version, one of 1.0, 1.0C, 1.1
# Protocol version 1.0C means version 1.0 with the addition
# of a "Connection: close" line, which is included in
# version 1.1 by default.
http_protocol <PROTOCOL>
# When alpha mode is set, or when recovering from a failure,
# each URL is checked, with a delay of <delay_loop> between
# each check. if there were 20 URLs, and the <delay_loop> were
# 3 seconds, it would take 1 minute before the RS would come up
# following startup, or recovery from a failure. Setting
# fast_recovery removes the delay, both at start up and after
# recovery from a failure, meaning that the RS will come up
# once all the URLs have been checked, with no delay between
# checking each URL.
fast_recovery [<BOOL>]
# An url to test
# can have multiple entries here
url {
#eg path / , or path /mrtg2/
path <STRING>
# healthcheck needs digest
# or status_code and digest
# Digest computed with genhash
# eg digest 9b3a0c85a887a256d6939da88aabd8cd
digest <STRING>
# status code returned in the HTTP header
# eg status_code 200 or status_code 200-299 400-499 503 505
# Default is 200-299
status_code <INTEGER|RANGE> [<INTEGER|RANGE>] ...
# VirtualHost string. eg virtualhost www.firewall.loc
# If not set, uses virtualhost from real or virtual server
virtualhost <STRING>
# Regular expression to search returned data against.
# A failure to match causes the check to fail.
regex <STRING>
# Reverse the sense of the match, so a match of the
# returned text causes the check to fail.
regex_no_match
# Space separated list of options for regex.
# See man pcre2api for a description of the options.
# The following option are supported:
# allow_empty_class alt_bsux auto_callout caseless
# dollar_endonly dotall dupnames extended firstline
# match_unset_backref multiline never_ucp never_utf
# no_auto_capture no_auto_possess no_dotstar_anchor
# no_start_optimize ucp ungreedy utf never_backslash_c
# alt_circumflex alt_verbnames use_offset_limit
regex_options <OPTIONS>
# For complicated regular expressions a larger stack
# may be needed, and this allows the start and maximum
# sizes in bytes to be specified. For more details see
# the documentation for pcre2_jit_stack_create()
regex_stack <START> <MAX>
# The minimum offset into the returned data to start
# checking for the regex pattern match. This can save
# processing time if the returned data is large.
regex_min_offset <OFFSET>
# The maximum offset into the returned data for the
# start of the subject match.
regex_max_offset <OFFSET>
}
}
SSL_GET {
# when provided, send Server Name Indicator during SSL handshake
enable_sni
}
# TCP healthchecker
TCP_CHECK {
# No additional options
}
# SMTP healthchecker
SMTP_CHECK {
# Optional string to use for the SMTP HELO request
helo_name <STRING>|<QUOTED-STRING>
}
# DNS healthchecker
DNS_CHECK {
# The retry default is 3.
# DNS query type
# A|NS|CNAME|SOA|MX|TXT|AAAA
# The default is SOA
type <STRING>
# Domain name to use for the DNS query
# The default is . (dot)
name <STRING>
}
# MISC healthchecker, run a program
MISC_CHECK {
# The retry default is 0.
# External script or program
misc_path <STRING>|<QUOTED-STRING>
# Script execution timeout
misc_timeout <INTEGER>
# If set, the exit code from healthchecker is used
# to dynamically adjust the weight as follows:
# exit status 0: svc check success, weight
# unchanged.
# exit status 1: svc check failed.
# exit status 2-255: svc check success, weight
# changed to 2 less than exit status.
# (for example: exit status of 255 would set
# weight to 253)
# NOTE: do not have more than one dynamic MISC_CHECK per real_server.
misc_dynamic
# Specify the username/groupname that the script should
# be run under.
# If GROUPNAME is not specified, the group of the user
# is used
user USERNAME [GROUPNAME]
}
# BFD instance name to check
BFD_CHECK {
name <STRING>
}
# PING healthchecker
# Note: using this checker may cause /proc/sys/net/ipv4/ping_group_range to be
# updated to allow root to use an IPPROTO_ICMP socket.
PING_CHECK {
# No additional options
}
# UDP healthchecker
# Note: for this checker to work properly, it relies on ICMP error messages such as
# HOST_UNREACH, NET_UNREACH, PORT_UNREACH. HOST_UNREACH relies on ARP requests
# timing out, and so connect_timeout should be long enough to allow for this (e.g.
# at least 4 seconds).
# It may be that you will want to use PING_CHECK to the same server as well.
UDP_CHECK {
require_reply # Require a reply packet for check to be successful
}
# File checker
# This reads and monitors the contents of a file, where STRING is the name specified
# in the track_file configuration block (see above).
# NOTE: weights for track_file for real servers are not fully implemented yet. In
# particular allowing weight 0, handling negative calculated values and reloading.
FILE_CHECK {
track_file <STRING>
# If dynamic is set, the value from the file is used
# to dynamically adjust the weight by adding the weight
# to the quorum and the LVS weight
dynamic
# The weight multiplier to apply to the value read from the file
weight <-2147483647..2147483647> [reverse]
}
}
}
# Parameters used for SSL_GET check.
# If none of the parameters are specified, the SSL context
# will be auto generated.
SSL {
# Password
password <STRING>
# CA file
ca <STRING>
# Certificate file
certificate <STRING>
# Key file
key <STRING>
}
ADVANCED CONFIGURATION
Configuration parser has been extended to support advanced features
such as conditional configuration and parameter substitution. These
features are very useful for any scripted environment where configura-
tion templates are generated (datacenters).
Conditional configuration and configuration id
The config-id defaults to the first part of the node name as returned
by uname, and can be overridden with the -i or --config-id command line
option.
Any configuration line starting with '@' is a conditional configuration
line. The word immediately following (i.e. without any space) the '@'
character is compared against the config-id, and if they don't match,
the configuration line is ignored.
Alternatively, '@^' is a negative comparison, so if the word immedi-
ately following does NOT match the config-id, the configuration line IS
included.
The purpose of this is to allow a single configuration file to be used
for multiple systems, where the only differences are likely to be the
router_id, vrrp instance priorities, and possibly interface names and
unicast addresses.
For example:
global_defs {
@main router_id main_router
@backup router_id backup_router
}
...
vrrp_instance VRRP {
...
@main unicast_src_ip 1.2.3.4
@backup unicast_src_ip 1.2.3.5
@backup2 unicast_src_ip 1.2.3.6
unicast_peer {
@^main 1.2.3.4
@^backup 1.2.3.5
@^backup2 1.2.3.6
}
...
}
If keepalived is invoked with -i main, then the router_id will be set
to main_router, if invoked with -i backup, then backup_router, if not
invoked with -i, or with -i anything else, then the router_id will not
be set. The unicast peers for main will be 1.2.3.5 and 1.2.3.6.
Parameter substitution
Substitutable parameters can be specified. The format for defining a
parameter is:
$PARAMETER=VALUE
where there must be no space before the '=' and only whitespace may
preceed to '$'. Empty values are allowed.
Parameter names can be made up of any combination of A-Za-z0-9 and _,
but cannot start with a digit. Parameter names starting with an under-
score should be considered reserved names that keepalived will define
for various pre-defined options.
After a parameter is defined, any occurrence of $PARAMETER followed by
whitespace, or any occurrence of ${PARAMETER} (which need not be fol-
lowed by whitespace) will be replaced by VALUE.
Replacement is recursive, so that if a parameter value itself includes
a replaceable parameter, then after the first substitution, the parame-
ter in the value will then be replaced; the substitution is done at
replacement time and not at definition time, so for example:
$ADDRESS_BASE=10.2.${ADDRESS_BASE_SUB}
$ADDRESS_BASE_SUB=0
${ADDRESS_BASE}.100/32
$ADDRESS_BASE_SUB=10
${ADDRESS_BASE}.100/32
will produce:
10.2.0.100/32
10.2.10.100/32
Note in the above examples the use of both ADDRESS_BASE and
ADDRESS_BASE_SUB required braces ({}) since the parameters were not
followed by whitespace (after the first substitution which produced
10.2.${ADDRESS_BASE_SUB}.100/32 the parameter is still not followed by
whitespace).
If a parameter is not defined, it will not be replaced at all, so for
example ${UNDEF_PARAMETER} will remain in the configuration if it is
undefined; this means that existing configuration that contains a '$'
character (for example in a script definition) will not be changed so
long as no new parameter definitions are added to the configuration.
Parameter substitution works in conjunction with conditional configura-
tion. For example:
@main $PRIORITY=240
@backup $PRIORITY=200
...
vrrp_instance VI_0 {
priority $PRIORITY
}
will produce:
...
vrrp_instance VI_0 {
priority 240
}
if the config_id is main.
$IF_MAIN=@main
$IF_MAIN priority 240
will produce:
priority 240
if the config_id is main and nothing if the config_id is not main,
although why anyone would want to use this rather than simply the
following is not known (but still possible):
@main priority 240
Multiline definitions are also supported, but when used there must be
nothing on the line after the parameter name. A multiline definition is
specified by ending each line except the last with a '\' character.
Example:
$INSTANCE= \
vrrp_instance VI_${NUM} {
\
interface eth0.${NUM} \
use_vmac vrrp${NUM}.1 \
virtual_router_id 1 \
@high priority 130 \
@low priority 120 \
advert_int 1 \
virtual_ipaddress {
\
10.0.${NUM}.254/24 \
} \
track_script {
\
offset_instance_${NUM} \
} \
}
$NUM=0
$INSTANCE
$NUM=1
$INSTANCE
The use of multiline definitions can be nested.
Example:
$RS= \
real_server 192.168.${VS_NUM}.${RS_NUM} 80 {
\
weight 1 \
inhibit_on_failure \
smtp_alert \
MISC_CHECK {
\
misc_path "${_PWD}/scripts/vs.sh RS_misc.${INST}.${VS_NUM}.${RS_NUM}.0 10.0.${VS_NUM}.4:80->192.168.${VS_NUM}.${RS_NUM}:80" \
} \
MISC_CHECK {
\
misc_path "${_PWD}/scripts/vs.sh RS_misc.${INST}.${VS_NUM}.${RS_NUM}.1 10.0.${VS_NUM}.4:80->192.168.${VS_NUM}.${RS_NUM}:80" \
} \
notify_up "${_PWD}/scripts/notify.sh RS_notify.${INST}.${VS_NUM}.${RS_NUM} UP 10.0.${VS_NUM}.4:80->192.168.${VS_NUM}.${RS_NUM}:80" \
notify_down "${_PWD}/scripts/notify.sh RS_notify.${INST}.${VS_NUM}.${RS_NUM} DOWN 10.0.${VS_NUM}.4:80->192.168.${VS_NUM}.${RS_NUM}:80" \
}
$VS= \
virtual_server 10.0.${VS_NUM}.4 80 {
\
quorum 2 \
quorum_up "${_PWD}/scripts/notify.sh VS_notify.${INST} UP 10.0.${VS_NUM}.4:80" \
quorum_down "${_PWD}/scripts/notify.sh VS_notify.${INST} DOWN 10.0.${VS_NUM}.4:80" \
$RS_NUM=1 \
$RS \
$RS_NUM=2 \
$RS \
$RS_NUM=3 \
$RS \
}
$VS_NUM=0
$ALPHA=alpha
$VS
$VS_NUM=1
$ALPHA=
$VS
The above will create 2 virtual servers, each with 3 real servers
Pre-defined definitions
The following pre-defined definitions are defined:
${_PWD} : The directory of the current configuration
file (this can be changed if using the include directive).
${_INSTANCE} : The instance name (as defined by the -i
option, defaults to hostname).
${_RANDOM [MIN [MAX]]} : This is replaced by a random
integer in the range [MIN, MAX], where MIN and MAX are optional non-
negative integers. Defaults are MIN=0 and MAX=32767.
Additional pre-defined definitions will be added as their need is iden-
tified. It will normally be quite straightforward to add additional
pre-defined definitions, so if you need one, or have a good idea for
one, then raise an issue at
https://github.com/acassen/keepalived/issues requesting it.
Sequence blocks
A line starting ~SEQ(var, start, step, end) will cause
the remainder of the line to be processed multiple times, with the
variable $var set initially to start,
and then $var will be incremented by
step repeatedly, terminating when it is greater than
end. step may be omitted, in which
case it defaults to 1 or -1, depending on whether end
is greater or less than start. start
may also be omitted, in which case it defaults to 1 if
end > 0 or -1 if end < 0.
~SEQx(...) is the same as ~SEQ(...), except the variable $var will for
formatted in hexadecimal, which would be useful for IPv6 addresses.
Note: At the moment it is necessary to use different variables for the
~SEQ block from any previously defined variable, including one used as
the variable in a previous ~SEQ block. This may change in the future,
so do not rely on a ~SEQ block variable being defined after the end of
the block.
Examples:
~SEQ(SUBNET, 0, 3) ip_address 10.0.${SUBNET}.1
would produce:
ip_address 10.0.0.1
ip_address 10.0.1.1
ip_address 10.0.2.1
ip_address 10.0.3.1
and
~SEQx(SUBNET, 144, 16, 192) ip_address fe80::20:${SUBNET}:1
or better
~SEQx(SUBNET, 0x90, 0x10, 0xc0) ip_address fe80::20:${SUBNET}:1
would produce:
ip_address fe80::20:90:1
ip_address fe80::20:a0:1
ip_address fe80::20:b0:1
ip_address fe80::20:c0:1
Another example:
virtual_ipaddress {
~SEQx(AD2, 0x90, 0x10, 0xc0) ~SEQx(AD1, 0x12, -1, 0x0c) fe81::10:${AD2}:${AD1}
}
There can be multiple ~SEQ elements on a line, so for example:
$VI4= \
track_file offset_instance_4.${IF}.${NUM}.${ID} {
\
file "${_PWD}/679/track_files/4.${IF}.${NUM}.${ID}" \
weight -100 \
} \
vrrp_instance vrrp4.${IF}.${NUM}.${ID} {
\
interface bond${IF}.${NUM} \
use_vmac vrrp4.${IF}.${NUM}.${ID} \
virtual_router_id ${ID} \
priority 130 \
virtual_ipaddress {
\
10.${IF}.${NUM}.${ID}/24 \
} \
track_file {
\
offset_instance_4.${IF}.${NUM}.${ID} \
} \
}
~SEQ(IF,0,7) ~SEQ(NUM,0,31) ~SEQ(ID,1,254) $VI4
will produce 65024 vrrp instances with names from vrrp4.0.0.1 through to
vrrp4.7.31.254.
List blocks
List blocks are similar to sequence blocks, except that the values to
substitute into the variable are listed in the ~LST specification.
A line starting ~LST(var, val1, val2, val3) will cause
the remainder of the line to be processed multiple times, with the
variable $var set initially to val1,
and then val2, and finally val3. Any
number of values can be specified, as long as at least one value is
(although only one value would be pointless).
If it is desired to substitute more than one variable at a time, the
variables and values need to be enclosed in {
...} blocks. For example:
~LST({
IP, IP1}, {
10,1},{
20,4},{
5,6},{
12,8}) 192.168.${IP}.${IP1}
would first set IP=10 and IP1=1, then IP=20 and IP1=4, etc, and pro-
duces:
192.168.10.1
192.168.20.4
192.168.5.6
192.168.12.8
List blocks can be nested, so:
~LST(IP, 1, 2, 3, 4) ~LST(IP1, 5,6,7) 192.169.${IP}.${IP1}
produces:
192.169.1.5
192.169.1.6
192.169.1.7
192.169.2.5
192.169.2.6
192.169.2.7
192.169.3.5
192.169.3.6
192.169.3.7
192.169.4.5
192.169.4.6
192.169.4.7
Finally, list blocks and sequence blocks can be combined, so:
~LST({
IP, IP1}, {
10,1},{
20,4},{
5,6},{
12,8}) ~SEQ(IP2,168,2,172)
192.${IP2}.${IP}.${IP1}
produces:
192.168.10.1
192.170.10.1
192.172.10.1
192.168.20.4
192.170.20.4
192.172.20.4
192.168.5.6
192.170.5.6
192.172.5.6
192.168.12.8
192.170.12.8
192.172.12.8
KERNEL SETTINGS
It has been identified that if proxy_arp and
proxy_arp_pvlan are enabled on an interface that has
VIPs or eVIPs configured on it, it can cause incorrect replies to ARP
requests due to the proxy replying to the ARP request as well as the
keepalived host. Both need to be set to 0 to function properly.
AUTHORS
Initial by Joseph Mack. Extensive updates by Alexandre Cassen & Quentin
Armitage.
SEE ALSO
ipvsadm(8), ip --help.
全局定义块
1、email通知（notification_email、smtp_server、smtp_connect_timeout）：用于服务有故障时发送邮件报警，可选项，不建议用。需要系统开启sendmail服务，建议用第三独立监控服务，如用Zabbix全面监控代替。
2、lvs_id：lvs负载均衡器标识，在一个网络内，它的值应该是唯一的。
3、router_id：用户标识本节点的名称，通常为hostname
4、花括号｛｝：用来分隔定义块，必须成对出现。如果写漏了，keepalived运行时不会得到预期的结果。由于定义块存在嵌套关系，因此很容易遗漏结尾处的花括号，这点需要特别注意。
VRRP实例定义块
vrrp_sync_group：同步vrrp级，用于确定失败切换（FailOver）包含的路由实例个数。即在有2个负载均衡器的场景，一旦某个负载均衡器失效，需要自动切换到另外一个负载均衡器的实例是哪
group：至少要包含一个vrrp实例，vrrp实例名称必须和vrrp_instance定义的一致
vrrp_instance：vrrp实例名
1> state：实例状态，只有MASTER 和 BACKUP两种状态，并且需要全部大写。抢占模式下，其中MASTER为工作状态，BACKUP为备用状态。当MASTER所在的服务器失效时，BACKUP所在的服务会自动把它的状态由BACKUP切换到MASTER状态。当失效的MASTER所在的服务恢复时，BACKUP从MASTER恢复到BACKUP状态。
2> interface：对外提供服务的网卡接口，即VIP绑定的网卡接口。如：eth0，eth1。当前主流的服务器都有2个或2个以上的接口（分别对应外网和内网），在选择网卡接口时，一定要核实清楚。
3> mcast_src_ip：本机IP地址
4> virtual_router_id：虚拟路由的ID号，每个节点设置必须一样，可选择IP最后一段使用，相同的 VRID 为一个组，他将决定多播的 MAC 地址。
5> priority：节点优先级，取值范围0～254，MASTER要比BACKUP高
6> advert_int：MASTER与BACKUP节点间同步检查的时间间隔，单位为秒
7> lvs_sync_daemon_inteface：负载均衡器之间的监控接口,类似于 HA HeartBeat 的心跳线。但它的机制优于 Heartbeat，因为它没有“裂脑”这个问题,它是以优先级这个机制来规避这个麻烦的。在 DR 模式中，lvs_sync_daemon_inteface与服务接口interface使用同一个网络接口
8> authentication：验证类型和验证密码。类型主要有 PASS、AH 两种，通常使用PASS类型，据说AH使用时有问题。验证密码为明文，同一vrrp 实例MASTER与BACKUP使用相同的密码才能正常通信。
9> smtp_alert：有故障时是否激活邮件通知
10> nopreempt：禁止抢占服务。默认情况，当MASTER服务挂掉之后，BACKUP自动升级为MASTER并接替它的任务，当MASTER服务恢复后，升级为MASTER的BACKUP服务又自动降为BACKUP，把工作权交给原MASTER。当配置了nopreempt，MASTER从挂掉到恢复，不再将服务抢占过来。
11> virtual_ipaddress：虚拟IP地址池，可以有多个IP，每个IP占一行，不需要指定子网掩码。注意：这个IP必须与我们的设定的vip保持一致。
虚拟服务器virtual_server定义块
virtual_server：定义一个虚拟服务器，这个ip是virtual_ipaddress中定义的其中一个，后面一个空格，然后加上虚拟服务的端口号。
1> delay_loop：健康检查时间间隔，单位：秒
2> lb_algo：负载均衡调度算法，互联网应用常用方式为wlc或rr
3> lb_kind：负载均衡转发规则。包括DR、NAT、TUN 3种，一般使用路由（DR）转发规则。
4> persistence_timeout：http服务会话保持时间，单位：秒
5> protocol：转发协议，分为TCP和UDP两种
real_server：真实服务器IP和端口，可以定义多个
1> weight：负载权重，值越大，转发的优先级越高
2> notify_down：服务停止后执行的脚本
3> TCP_CHECK：服务有效性检测
- connect_port：服务连接端口
- connect_timeout：服务连接超时时长，单位：秒
- nb_get_retry：服务连接失败重试次数
- delay_before_retry：重试连接间隔，单位：秒