[Automated operation and maintenance] Application of common modules of Ansible

1. Introduction to Ansible

• Ansible is a configuration management and application deployment tool based on Python, and now it is also shining in the field of automation management. It combines the advantages of many old-fashioned operation and maintenance tools. Ansible can basically achieve the functions that Pubbet and Saltstack can achieve.

• Ansible can configure, deploy, and manage thousands of hosts in batches. For example, in the past, it was necessary to switch to one or more operations performed on each host, but using Ansible only needs to complete the operations of all hosts on a fixed Ansible control node.

• Ansible works based on modules. It just provides a running framework. It does not have the ability to complete tasks. It is Ansible modules that actually perform operations. For example, the copy module is used to copy files to remote hosts, and the service module is used to manage Start, stop, restart, etc. of the service.

• One of the more distinctive features of Ansible is Agentless, that is, there is no Agent. It is like an ordinary command, not a C/S software. It only needs to install Ansible once on a host as a control node. Usually it is based on ssh connection to control the remote host, there is no need to install Ansible or other additional services on the remote host.

• When users use it, they input commands or playbooks on the server terminal, and the playbook will be disassembled into plays according to predetermined rules, and then organized into tasks that can be recognized by ansible, calling modules and plug-ins, and sending temporary files through SSH according to the host list. Execute and return the result to the remote client, and delete it automatically after execution

• Another distinctive feature of Ansible is that most of its modules are idempotent. The so-called idempotence means that no matter how many times the same operation is performed, the result is the same, that is, the impact of any number of executions of a command is the same as that of one execution. For example, execute the systemctl stop xxx command to stop the service. When it finds that the target service to be stopped is already in the stopped state, it will not do anything, so the result of multiple stops is still stopped, and the result will not be changed. It is idempotent. And systemctl restart xxx is non-idempotent.

• Many modules of Ansible will first judge whether the target node wants to execute the task when executing it. Therefore, you can safely and boldly let Ansible execute the task. Most of the time, repeated execution of a task will not cause any side effects.

2. Ansible installation and deployment

2.1 Environment preparation

Serve	IP	application
Management side	192.168.243.100	ansible
managed end	192.168.243.102
managed end	192.168.243.103

Install ansible on the management side

yum install -y epel-release			//先安装 epel 源
yum install -y ansible

ansible directory structure

/etc/ansible/
├── ansible.cfg			#ansible的配置文件，一般无需修改
├── hosts				#ansible的主机清单，用于存储需要管理的远程主机的相关信息
└── roles/				#公共角色目录

Configure host list

cd /etc/ansible
vim hosts       
[webservers]			#配置组名
192.168.243.102			#组里包含的被管理的主机IP地址或主机名（主机名需要先修改/etc/hosts文件）

[dbservers]
192.168.243.103

Configure key pair authentication

ssh-keygen -t rsa -P '' -f ~/.ssh/id_rsa

yum install -y sshpass
sshpass -p 'abc1234' ssh-copy-id -o StrictHostKeyChecking=no [email protected]
sshpass -p 'abc1234' ssh-copy-id -o StrictHostKeyChecking=no [email protected]   

ble command module

• Command format: ansible <group name> -m <module> -a <parameter list>

ansible-doc -l				#列出所有已安装的模块，按q退出

3. Ansible command line module

3.1. command module

//在远程主机执行命令，不支持管道，重定向等shell的特性。
ansible-doc -s command		#-s 列出指定模块的描述信息和操作动作

ansible 192.168.80.11 -m command -a 'date'		#指定 ip 执行 date
ansible webservers -m command -a 'date'			#指定组执行 date
ansible dbservers -m command -a 'date'       
ansible all -m command -a 'date'				#all 代表所有 hosts 主机
ansible all -a 'ls /'							#如省略 -m 模块，则默认运行 command 模块

//常用的参数：
chdir：在远程主机上运行命令前提前进入目录
creates：判断指定文件是否存在，如果存在，不执行后面的操作
removes：判断指定文件是否存在，如果存在，执行后面的操作

ansible all -m command -a "chdir=/home  ls ./"

3.2. shell module

//在远程主机执行命令，相当于调用远程主机的shell进程，然后在该shell下打开一个子shell运行命令（支持管道符号等功能）
ansible-doc -s shell

ansible dbservers -m shell -a 'echo 123456 | passwd --stdin test"'
ansible dbservers -m shell -a 'echo $(ifconfig ens33 | awk "NR==2 {print $2}") | cut -d " " -f2'
ansible dbservers -m shell -a 'echo $(ifconfig ens33 | awk "NR==2 {print \$2}")'

3.3. cron module

//在远程主机定义任务计划。其中有两种状态（state）：present表示添加（可以省略），absent表示移除。
ansible-doc -s cron				#按 q 退出

//常用的参数：
minute/hour/day/month/weekday：分/时/日/月/周
job：任务计划要执行的命令
name：任务计划的名称
user：指定计划任务属于哪个用户，默认是root用户

ansible webservers -m cron -a 'minute="*/1" job="/bin/echo helloworld" name="test crontab"'
ansible webservers -a 'crontab -l'
ansible webservers -m cron -a 'name="test crontab" state=absent'

3.4．user module

//用户管理的模块
ansible-doc -s user

//常用的参数：
name：用户名，必选参数
state=present|absent：创建账号或者删除账号，present表示创建，absent表示删除
system=yes|no：是否为系统账号
uid：用户uid
group：用户基本组
groups: 用户所属附加组
shell：默认使用的shell
create_home=yse|no: 是否创建家目录
password：用户的密码，建议使用加密后的字符串
remove=yes|no：当state=absent时，是否删除用户的家目录

ansible dbservers -m user -a 'name="test01"'				#创建用户test01
ansible dbservers -m command -a 'tail /etc/passwd'
ansible dbservers -m user -a 'name="test01" state=absent'	#删除用户test01

3.5．group module

//用户组管理的模块
ansible-doc -s group

ansible dbservers -m group -a 'name=mysql gid=306 system=yes'	#创建mysql组
ansible dbservers -a 'tail /etc/group'
ansible dbservers -m user -a 'name=test01 uid=306 system=yes group=mysql'	#将test01用户添加到mysql组中
ansible dbservers -a 'tail /etc/passwd'
ansible dbservers -a 'id test01'    

3.6. copy module

//用于复制指定主机文件到远程主机的
ansible-doc -s copy

//常用的参数：
dest：指出复制文件的目标及位置，使用绝对路径，如果源是目录，指目标也要是目录，如果目标文件已经存在会覆盖原有的内容
src：指出源文件的路径，可以使用相对路径或绝对路径，支持直接指定目录，如果源是目录则目标也要是目录
mode：指出复制时，目标文件的权限 
owner：指出复制时，目标文件的属主
group：指出复制时，目标文件的属组
content：指出复制到目标主机上的内容，不能与src一起使用

ansible dbservers -m copy -a 'src=/etc/fstab dest=/opt/fstab.bak owner=root mode=640'
ansible dbservers -a 'ls -l /opt'
ansible dbservers -a 'cat /opt/fstab.bak'

ansible dbservers -m copy -a 'content="helloworld" dest=/opt/hello.txt'  #将helloworld写入/opt/hello.txt文件中
ansible dbservers -a 'cat /opt/hello.txt' 

3.7．file module

//设置文件属性
ansible-doc -s file

ansible dbservers -m file -a 'owner=test01 group=mysql mode=644 path=/opt/fstab.bak'	#修改文件的属主属组权限等
ansible dbservers -m file -a 'path=/opt/fstab.link src=/opt/fstab.bak state=link'    #设置/opt/fstab.link为/opt/fstab.bak的链接文件
ansible dbservers -m file -a "path=/opt/abc.txt state=touch"			#创建一个文件
ansible dbservers -m file -a "path=/opt/abc.txt state=absent"			#删除一个文件

8. hostname module

//用于管理远程主机上的主机名
ansible dbservers -m hostname -a "name=mysql01"

3.9．ping module

//检测远程主机的连通性
ansible all -m ping

3.10．yum module

//在远程主机上安装与卸载软件包
ansible-doc -s yum

ansible webservers -m yum -a 'name=httpd'					#安装服务
ansible webservers -m yum -a 'name=httpd state=absent'		#卸载服务

3.11. service/systemd module

//用于管理远程主机上的管理服务的运行状态
ansible-doc -s service

//常用的参数：
name：被管理的服务名称
state=started|stopped|restarted：动作包含启动关闭或者重启
enabled=yes|no：表示是否设置该服务开机自启
runlevel：如果设定了enabled开机自启去，则要定义在哪些运行目标下自启动

ansible webservers -a 'systemctl status httpd'			#查看web服务器httpd运行状态
ansible webservers -m service -a 'enabled=true name=httpd state=started'			#启动httpd服务

3.12. script module

//实现远程批量运行本地的 shell 脚本
ansible-doc -s script

vim test.sh
#!/bin/bash
echo "hello ansible from script" > /opt/script.txt

chmod +x test.sh
ansible webservers -m script -a 'test.sh'
ansible webservers -a 'cat /opt/script.txt'

vim test.sh
#!/bin/bash
echo $1 > /opt/test.txt
echo s2 >> /opt/test .txt

ansible dbservers -m script -a 'test.sh abc 123!

3.13. mount module

//挂载文件系统
ansible-doc -s mount

//常用的参数：
src：定义挂载设备的路径
path：定义挂载到哪个目录，必须指定
fstype：指定挂载文件的系统类型，必须指定，xfs、iso9660、nfs...
opts：定义挂载的参数，defaults、rw、ro...
state：定义挂载的状态，mounted（进行挂载，修改/etc/fstab信息）、absent（永久性卸载，并修改 /etc/fstab信息）、unmounted（临时卸载，不修改/etc/fstab信息）

ansible dbservers -m mount -a 'src=/dev/sr0 path=/mnt state=mounted fstype=iso9660'

3.14. archive module

//打包压缩
ansible-doc -s archive

//常用的参数：
path: 必须参数，远程主机上需要被打包压缩的源文件/目录
dest: 打包压缩后的包文件路径(包文件的父目录必须存在);如果包文件已存在，则会被覆盖
format: 指定压缩类型，包括: bz2、gz（默认）、tar、xz、zip
remove=yes|no: 是否删除源文件

ansible dbservers -m archive -a "path=/etc/yum.repos.d/ dest=/opt/repo.zip format=zip"
ansible dbservers -m archive -a "path=/opt/abc.txt,/opt/123.txt dest=/opt/abc123.tar.gz format=gz remove=yes"

3.15. unarchive module

//解包解压缩
ansible-doc -s unarchive

//常用的参数：
copy：默认为 copy=yes ，拷贝的文件从 ansible 主机复制到远程主机，copy=no 表示在远程主机上寻找源文件解压
src：tar包源路径，可以是 ansible 主机上的路径，也可以是远程主机上的路径，如果是远程主机上的路径，则需设置 copy=no
dest：解压后文件的目标绝对路径
remote_src: 和 copy 功能一样且互斥，设置 remote_src=yes 表示文件在远程主机上，设置为 remote_src=no 表示文件在 ansible 主机上

#将 ansible 主机的压缩文件拷贝到到远程主机并解压，修改文件所属组和用户
ansible dbservers -m unarchive -a "src=/opt/abc.tar.gz dest=/root copy=yes"
或者
ansible dbservers -m unarchive -a "src=/opt/abc.tar.gz dest=/root remote_src=no"

#在远程主机解包
ansible dbservers -m unarchive -a "src=/opt/123.tar.gz dest=/root copy=no"
或者
ansible dbservers -m unarchive -a "src=/opt/123.tar.gz dest=/root remote_src=yes"

3.16. replace module

/

/类似于sed命令，主要也是基于正则进行匹配和替换
ansible-doc -s replace

//常用的参数:
path：必须参数，指定要修改的文件
regexp：必须参数，指定一个正则表达式
replace：替换regexp参数匹配到的字符串
backup=yes|no: 修改源文件前创建一个包含时间戳信息的备份文件
before：如果指定，则仅替换/删除此匹配之前的内容，可以和after参数结合使用
after：如果指定，则仅替换/删除此匹配之后的内容，可以和before参数结合使用
owner：修改文件用户名
group：修改文件组名
mode：修改文件权限

vim /opt/test.txt
11 22 33 44 55 66
aa bb cc dd ee ff
1a 2b 3c 4d 5e 6f

#匹配 333 并修改为 ccc
ansible dbservers -m replace -a "path=/opt/test.txt regexp='33' replace='cc'"
#匹配到任意一个或多个开头的行增加注释
ansible dbservers -m replace -a "path=/opt/test.txt regexp='^(.*)' replace='#\1'"
#取消注释
ansible dbservers -m replace -a "path=/opt/test.txt regexp='^#(.*)' replace='\1'"
#匹配以 a 开头的后面有一个或者多个字符的行，并在前面添加 # 注释
ansible dbservers -m replace -a "path=/opt/test.txt regexp='^(a.*)' replace='#\1'"

ansible dbservers -m replace -a "path=/opt/test.txt regexp='3' replace='three' before=cc"

3.17．setup module

//facts 组件是用来收集被管理节点信息的，使用 setup 模块可以获取这些信息
ansible-doc -s setup

ansible webservers -m setup				#获取mysql组主机的facts信息
ansible dbservers -m setup -a 'filter=*ipv4'    #使用filter可以筛选指定的facts信息

Four, inventory host list

• Inventory supports grouping of hosts. Multiple hosts can be defined in each group, and each host can be defined in any one or more host groups.

If there are hosts with similar names, you can use a list to identify each host.

vim /etc/ansible/hosts
[webservers]
192.168.80.11:2222		#冒号后定义远程连接端口，默认是 ssh 的 22 端口
192.168.80.1[2:5]

[dbservers]
db-[a:f].example.org	#支持匹配 a~f

Variables in inventory

Inventory variable name	meaning
ansible_host	IP address when ansible connects to the node
ansible_port	The port number of the other party to connect to, the default is 22 for ssh connection
ansible_user	The username used when connecting to the other host. When not specified, the user who executes the ansible or ansible-playbook command will be used
ansible_password	The user's ssh password when connecting, only valid if the key pair is not used for authentication
ansible_ssh_private_key_file	Specify the private key file for key authentication ssh connection
ansible_ssh_common_args	Additional parameters provided to ssh, sftp, scp commands
ansible_become	Allow privilege escalation
ansible_become_method	Specify the way to elevate privileges, for example, sudo/su/runas can be used
ansible_become_user	Which user's authority to upgrade to, the default is root
ansible_become_password	Password when elevating to specified user privileges

(1) Host variables

[webservers]
192.168.80.11 ansible_port=22 ansible_user=root ansible_password=abc1234

(2) Group variables

[webservers:vars]			#表示为 webservers 组内所有主机定义变量
ansible_user=root
ansible_password=abc1234

[all:vars]					#表示为所有组内的所有主机定义变量
ansible_port=22

(3) Group nesting

[nginx]
192.168.80.20
192.168.80.21
192.168.80.22

[apache]
192.168.80.3[0:3]

[webs:children]		#表示为 webs 主机组中包含了 nginx 组和 apache 组内的所有主机
nginx
apache