O Docker instala o Keepalived + Nginx e obtém alta disponibilidade
Diretório do artigo
Objetivo da demanda: instalar o Keepalived + Nginx com base na imagem do Centos e obter alta disponibilidade
Preparação
Faça o download da imagem centos e configure o ambiente
$ docker pull centos # 拉取最新 centos
$ docker images # 查看镜像
$ docker run -itd --name centos centos # 后台启动一个容器
$ docker exec -it centos bash # 进入容器
$ yum -y upgrade # 升级所有包
$ yum install -y yum-utils vim make wget gcc openssl openssl-devel popt-devel # 安装相关依赖
Baixe e instale o Nginx
Configurar fonte yum
Documento de referência oficial http://nginx.org/en/linux_packages.html
$ cat /etc/yum.repos.d/nginx.repo
[nginx-stable]
name=nginx stable repo
baseurl=http://nginx.org/packages/centos/$releasever/$basearch/
gpgcheck=1
enabled=1
gpgkey=https://nginx.org/keys/nginx_signing.key
module_hotfixes=true
[nginx-mainline]
name=nginx mainline repo
baseurl=http://nginx.org/packages/mainline/centos/$releasever/$basearch/
gpgcheck=1
enabled=0
gpgkey=https://nginx.org/keys/nginx_signing.key
module_hotfixes=true
$ yum install -y nginx # 安装 Nginx
$ whereis nginx # 查看安装路径,默认配置文件在 /etc/nginx
$ nginx -t # 插件配置
$ nginx # 启动
$ curl localhost # 检查启动是否成功
Baixe e instale o Keepalived
Keepalived site oficial baixar a versão mais recente
$ mkdir -p /mnt/software && cd /mnt/software
$ wget https://www.keepalived.org/software/keepalived-2.0.20.tar.gz
$ docker cp keepalived-2.0.20.tar.gz centos:/mnt/ # 下载慢!!也可以从本地 copy
$ tar -zxvf keepalived-2.0.20.tar.gz
Compilar e instalar
$ cd keepalived-2.0.20
$ ./configure --prefix=/usr/local/keepalived
O seguinte aviso pode aparecer após a compilação
*** WARNING - this build will not support IPVS with IPv6. Please install libnl/libnl-3 dev libraries to support IPv6 with IPVS.
Siga as instruções
$ yum -y install libnl libnl-devel
No match for argument: libnl
No match for argument: libnl-devel
Error: Unable to find a match: libnl libnl-devel
Só precisamos usar a função VRRP, desde que use VRRP Framework, use VRRP VMAC, use VRRP VMAC, use VRRP authentication for Sim, é claro, você também pode encontrar o RPM para instalar a libnl separadamente.
https://centos.pkgs.org/7/centos-x86_64/libnl-1.1.4-3.el7.x86_64.rpm.html
$ wget http://mirror.centos.org/centos/7/os/x86_64/Packages/libnl-1.1.4-3.el7.x86_64.rpm
$ wget http://mirror.centos.org/centos/7/os/x86_64/Packages/libnl-devel-1.1.4-3.el7.x86_64.rpm
$ rpm -ivh libnl-1.1.4-3.el7.x86_64.rpm
$ rpm -ivh libnl-devel-1.1.4-3.el7.x86_64.rpm
$ ./configure --prefix=/usr/local/keepalived
$ make && make install
Configurar Keepalived
$ cp /mnt/software/keepalived-2.0.20/keepalived/etc/init.d/keepalived /etc/init.d/
$ cp /mnt/software/keepalived-2.0.20/keepalived/etc/sysconfig/keepalived /etc/sysconfig/
$ cp /usr/local/keepalived/sbin/keepalived /usr/sbin/
$ mkdir -p /etc/keepalived
$ cp /usr/local/keepalived/etc/keepalived/keepalived.conf /etc/keepalived/
$ chmod +x /etc/init.d/keepalived
$ ip address # 本机 ip 172.17.0.2 网卡 eth0
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
2: tunl0@NONE: <NOARP> mtu 1480 qdisc noop state DOWN group default qlen 1000
link/ipip 0.0.0.0 brd 0.0.0.0
3: ip6tnl0@NONE: <NOARP> mtu 1452 qdisc noop state DOWN group default qlen 1000
link/tunnel6 :: brd ::
22: eth0@if23: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default
link/ether 02:42:ac:11:00:02 brd ff:ff:ff:ff:ff:ff link-netnsid 0
inet 172.17.0.2/16 brd 172.17.255.255 scope global eth0
valid_lft forever preferred_lft forever
Os arquivos de configuração keepalived são colocados em /etc/keepalived/keepalived.conf por padrão
! Configuration File for keepalived
global_defs {
# 负载均衡标识,在局域网内应该是唯一的
router_id LVS_DEVEL
enable_script_security
# 建议新建用户来执行脚本
script_user root
}
vrrp_script chk_nginx {
script "/etc/keepalived/check.sh"
# 每2秒检测一次nginx的运行状态
interval 2
# 失败一次,将自己的优先级调整为-5
weight -5
# require 2 failures for KO
fall 2
# require 2 successes for OK
rise 2
}
vrrp_instance VI_1 {
# 标示状态为 MASTER 备份机为 BACKUP
state MASTER
# 设置实例绑定的网卡
interface eth0
# 同一实例下 virtual_router_id 必须相同
virtual_router_id 51
# MASTER 权重要高于 BACKUP 比如 BACKUP 为99
priority 100
# MASTER 与 BACKUP 负载均衡器之间同步检查的时间间隔,单位是秒
advert_int 1
# 设置认证
authentication {
# 主从服务器验证方式
auth_type PASS
auth_pass 1111
}
# 虚拟IP,两个节点设置必须一致,可以设置多个
virtual_ipaddress {
172.17.0.200
172.17.0.210
}
track_script {
chk_nginx
}
}
$ cd /etc/keepalived
$ touch check.sh
$ chmod +x check.sh
O conteúdo do script check.sh é o seguinte
#!/bin/bash
Nginx=`ps -ef | grep nginx | grep -v grep | wc -l`
echo 'nginx status ' $Nginx
if [ $Nginx -eq 0 ]
then
echo 'nginx shutdown...'
nginx
echo 'start nginx ...'
sleep 2
if [ `ps -ef | grep nginx | grep -v grep | wc -l` -eq 0 ]
then
ps -ef | grep keepalived | grep -v grep | awk '{print $2}' | xargs kill -9
echo 'kill keepalived...'
else
echo 'nginx started...'
fi
fi
echo 'script end...'
A função do script: quando o processo nginx não existe, ele reinicia automaticamente o serviço nginx, dorme por 2 segundos e verifica novamente o processo nginx, se não existir, interrompa o serviço de manutenção de atividade
Script de teste:
$ ps ax|grep nginx
40 pts/1 S+ 0:00 grep --color=auto nginx
$ ./check.sh
nginx status 0
nginx shutdown...
start nginx ...
nginx started...
script end...
$ ps ax|grep nginx
48 ? Ss 0:00 nginx: master process nginx
49 ? S 0:00 nginx: worker process
57 pts/1 S+ 0:00 grep --color=auto nginx
Verifique a configuração
$ keepalived -t
Neste ponto, Keepalived e Nginx estão configurados.
Teste
Instantâneo de criação de contêiner
$ docker ps -a | grep centos
ace32d2fa597 centos "/bin/bash" About an hour ago Up About an hour centos
$ docker commit ace32d2fa597 centos_keepalived_nginx:0.0.1 # 创建该容器的快照
$ docker images | grep centos_keepalived_nginx
centos_keepalived_nginx 0.0.1 801e75c18232 51 seconds ago 569MB
Criar um contêiner mestre-escravo
Crie um contêiner mestre-escravo com base na captura instantânea
$ docker run --privileged -itd -p 6698:80 --name keepalived_master --hostname keepalived_master centos_keepalived_nginx:0.0.1 /usr/sbin/init
$ docker run --privileged -itd -p 6699:80 --name keepalived_slave --hostname keepalived_slave centos_keepalived_nginx:0.0.1 /usr/sbin/init
Digite o contêiner de maser para modificar a configuração
$ docker exec -it keepalived_master bash # 进入 master 容器
$ vi /usr/share/nginx/html/index.html # 任意修改一点内容与 slave 做区分
$ nginx
$ curl localhoast
Digite o contêiner escravo para modificar a configuração
$ docker exec -it keepalived_master bash # 进入 master 容器
$ vi /usr/share/nginx/html/index.html # 任意修改一点内容与 slave 做区分
$ nginx
$ curl localhoast
Keepalived do teste
Iniciar manutenção mantida no contêiner mestre
$ docker exec -it keepalived_master bash
$ keepalived
$ curl 172.17.0.200 # curl 172.17.0.210
$ ip address
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
2: tunl0@NONE: <NOARP> mtu 1480 qdisc noop state DOWN group default qlen 1000
link/ipip 0.0.0.0 brd 0.0.0.0
3: ip6tnl0@NONE: <NOARP> mtu 1452 qdisc noop state DOWN group default qlen 1000
link/tunnel6 :: brd ::
36: eth0@if37: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default
link/ether 02:42:ac:11:00:02 brd ff:ff:ff:ff:ff:ff link-netnsid 0
inet 172.17.0.2/16 brd 172.17.255.255 scope global eth0
valid_lft forever preferred_lft forever
inet 172.17.0.200/32 scope global eth0
valid_lft forever preferred_lft forever
inet 172.17.0.210/32 scope global eth0
valid_lft forever preferred_lft forever
Iniciar keepalived no contêiner escravo
$ docker exec -it keepalived_slave bash
$ vi /etc/keepalived/keepalived.conf # state 改为 BACKUP priority 改为 小于 100 的任意值 比如 99
$ keepalived
$ curl 172.17.0.200 # curl 172.17.0.210
Resumo:
-
Você encontrará que o acesso a 172.17.0.200 e 172.17.0.210 acessa o conteúdo no contêiner de maser
-
Se você desativar o keepalived no mestre, ele mudará automaticamente para o conteúdo no contêiner escravo
-
Quando o processo nginx não existir, tente reiniciar o nginx.Se o nginx falhar ao iniciar, encerre o serviço keepalived e implemente a alternância automática.
Problemas restantes:
- Como o IP virtual definido no Docker pode ser acessado pela rede externa e como mapeá-lo? A pesquisa do Docker não é aprofundada, por favor, informe.
- O script check.sh verifica se o serviço Nginx tem tempo para retornar 0 e às vezes retorna 2 (os serviços Nginx estão todos fechados), mas usar o toque para criar um novo arquivo não é problema! ! ! Por que isso?
Bem-vindo ao se comunicar juntos ...