Ansible 流程控制 -- 01

Posted 2021-05-16 FikL-09-19

Ansible 流程控制

一、playbook 条件语句

不管是shell还是各大编程语言中，流程控制，条件判断这些都是必不可少的，在我们使用Ansible的过程中，条件判断的使用频率极其高。
例如：
1.我们使用不同的系统的时候，可以通过判断系统来对软件包进行安装。
2.在nfs和rsync安装过程中，客户端服务器不需要推送配置文件，之前我们都是写多个play，会影响效率。
3.我们在源码安装nginx的时候，执行第二遍就无法执行了，此时我们就可以进行判断是否安装过。

1.判断系统

# ansible判断
[root@m01 ~]# ansible web01 -m setup
[root@m01 ~]# vim xitong.yml
- hosts: web_group
  tasks:
    - name: Install Centos httpd
      shell: "yum install -y httpd"
      when: ansible_distribution == "CentOS" 

    - name: Install Ubuntu httpd
      shell: "apt-get apache2"
      when: ansible_distribution == "Ubuntu"

2.判断主机

[root@m01 ~]# cat base.yml
- hosts: nfs_group
  tasks:
    - name: Create www Group
      group:
        name: www
        gid: 666
        state: present
      when: ansible_fqdn != "nfs"

    - name: Create www User
      user:
        name: www
        uid: 666
        group: www
        shell: /sbin/nologin
        create_home: false
        state: present
      when: ansible_fqdn != "nfs"

3.判断服务是否安装

[root@m01 ~]# cat php.yml  
- hosts: web_group
  tasks:
    - name: Tar php Package
      unarchive:
        src: /root/package/php.tar.gz
        dest: /tmp/
    
    #使用shell模块，检查php是否安装，将结果赋值给注册的变量
    - name: Check php Install Status
      shell: "rpm -qa | grep php | wc -l"
      register: get_php_instll_status
 
    #调用注册的变量，当变量中stdout_lines为0的时候，才会安装php
    - name: Install php Server
      shell: "yum localinstall -y /tmp/*.rpm"
      when: get_php_instll_status.stdout_lines == 0

4.判断系统版本启动服务

# 1、写法一：使用列表的形式
[root@m01 ~]# vim startserver.yml
- hosts: web_group
  tasks:
    - name: Start CentOS 6 Server
      shell: "/etc/init.d/httpd start"
      when:
        - ansible_distribution == "CentOS"
        - ansible_distribution_major_version == "6"

    - name: Start CentOS 7 Server
      shell: "systemctl restart httpd"
      when:
        - ansible_distribution == "CentOS"
        - ansible_distribution_major_version == "7"

# 2、写法二：多条件and连接（or是或者）
[root@m01 ~]# vim startserver.yml
- hosts: web_group
  tasks:
    - name: Start CentOS 6 Server
      shell: "/etc/init.d/httpd start"
      when: (ansible_distribution == "CentOS") and (ansible_distribution_major_version == "6")

    - name: Start CentOS 7 Server
      shell: "systemctl restart httpd"
      when: (ansible_distribution == "CentOS") and (ansible_distribution_major_version == "7")

5.判断服务是否启动

[root@m01 ~]# vim web.yml
- hosts: web_group
  tasks:
    - name: Check Httpd Server
      command: systemctl is-active httpd
      ignore_errors: yes
      register: check_httpd

    - name: debug outprint
      debug: var=check_httpd

    - name: Httpd Restart
      service:
        name: httpd
        state: restarted
      when: check_httpd.rc == 0

二、playbook 循环语句

在之前的学习过程中，我们经常会有传送文件，创建目录之类的操作，创建2个目录就要写两个file模块来创建，如果要创建100个目录，我们需要写100个file模块？？？妈耶~~~~ 当然不是，只要有循环即可，减少重复性代码。

1.定义循环安装服务

[root@m01 ~]# vim install.yml 
- hosts: nfs_group
  tasks:
    - name: install server
      yum:
        name:  "{{ page }}"
        state: present
      vars:
        page:
          - tree
          - nfs-utils
          - httpd

2.定义循环启动服务

#错误写法
[root@m01 ~]# vim start.yml
- hosts: nfs_group
  tasks:
    - name: Start Server
      systemd:
        name: "{{ package }}"
        state: started
      vars:
        package:
          - nfs-utils
          - httpd
          - tree

#正确写法
[root@m01 ~]# vim start.yml
- hosts: nfs_group
  tasks:
    - name: Start Server
      systemd:
        name: "{{ item }}"
        state: started
      with_items:
        - nfs-utils
        - httpd
        - tree

3.字典定义变量

# 1.创建多个用户和组
[root@m01 ~]# cat user.yml   
- hosts: all    #  1.创建多个组
  tasks:
    - name: Create Some Group
      group:
        name: "{{ item.name }}"
        gid: "{{ item.gid }}"
        state: present
      with_items:
        - { name: "mm", gid: "1000" }
        - { name: "ping", gid: "1001" }
        - { name: "egon", gid: "1002" }
        
    - name: Create Some User  # 2.创建多个用户
      user:
        name: "{{ item.name }}"
        uid: "{{ item.uid }}"
        group: "{{ item.group }}"
        shell: "{{ item.shell }}"
        create_home: "{{ item.create_home }}"
      with_items:
        - { name: "mm", uid: "1000", group: "mm", shell: "/sbin/nologin", create_home: "false" }
        - { name: "ping", uid: "1001", group: "ping", shell: "/bin/bash", create_home: "false" }
        - { name: "egon", uid: "1002", group: "egon", shell: "/bin/bash", create_home: "true" }

三、playbook handlers 触发器

1.什么是handlers?

handler用来执行某些条件下的任务，比如当配置文件发生变化的时候，通过notify触发handler去重启服务。
在saltstack中也有类似的触发器，写法相对Ansible简单，只需要watch，配置文件即可。

2.配置触发器

[root@m01 ~]# cat nginx.yml 
- hosts: web01
  tasks:
    - name: Config Nginx Server
      copy:
        src: /etc/nginx/nginx.conf
        dest: /etc/nginx/
      notify: restart_nginx

    - name: Start Nginx Server
      systemd:
        name: nginx
        state: started

  handlers:
    - name: restart_nginx
      systemd:
        name: nginx
        state: restarted

3.触发器使用注意事项

1.无论多少个task通知了相同的handlers，handlers仅会在所有tasks结束后运行一次。

2.Handlers只有在其所在的任务被执行时，才会被运行；如果一个任务中定义了notify调用Handlers，但是由于条件判断等原因，该任务未被执行，那么Handlers同样不会被执行。

3.Handlers只会在每一个play的末尾运行一次；如果想在一个playbook中间运行Handlers，则需要使用meta模块来实现。例如： -meta: flush_handlers。

4.如果一个play在运行到调用Handlers的语句之前失败了，那么这个Handlers将不会被执行。我们可以使用meta模块的--force-handlers选项来强制执行Handlers，即使Handlers所在的play中途运行失败也能执行。

5.不能使用handlers替代tasks

4.简单优化后的php文件

[root@m01 ~]# cat php.yml 
- hosts: web_group
  tasks:
    - name: Tar php Package
      unarchive:
        src: /~/package/php.tar.gz
        dest: /tmp/

    - name: Check php Install Status
      shell: "rpm -qa | grep php | wc -l"
      register: get_php_instll_status

    - name: Install php Server
      shell: "yum localinstall -y /tmp/*.rpm"
      when: get_php_instll_status.stdout_lines == 0

    - name: Config php Server
      copy:
        src: "{{ item.src }}"
        dest: "{{ item.dest }}"
      with_items:
        - { src: "/~/conf/php.ini", dest: "/etc" }
        - { src: "/~/conf/www.conf", dest: "/etc/php-fpm.d/" }
      notify: restart_php

    - name: Start php Server
      systemd:
        name: php-fpm
        state: started

  handlers:
    - name: restart_php
      systemd:
        name: php-fpm
        state: restarted