自动化运维Ansible实践

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上篇提到了ansible基本安装、配置及命令行使用,这篇分享下ansible的高级用法即playbook,在生产环境如果需要完成负责任务,如大批量服务安装配置等,可以采用playbook方式来完成,高效且易于维护。

第 1 章 Playbook基本使用

使用Playbook的好处
特点
? 易读的编排语言
? 适合配置管理和应用部署
? 非常适合部署复杂的工作
先来认识一下Playbook
自动部署nginx

main.yml


  • hosts: webservers
    vars:
    hello: Ansible

    tasks:

    • name: Add repo
      yum_repository:
      name: nginx
      description: nginx repo
      baseurl: http://nginx.org/packages/centos/3/$basearch/
      gpgcheck: no
      enabled: 1
    • name: Install nginx
      yum:
      name: nginx
      state: latest
    • name: Copy nginx configuration file
      copy:
      src: ./site.conf
      dest: /etc/nginx/conf.d/site.conf
    • name: Start nginx
      service:
      name: nginx
      state: started
    • name: Create wwwroot directory
      file:
      dest: /var/www/html
      state: directory
    • name: Create test page index.html
      shell: echo "hello {{hello}}" > /var/www/html/index.html

site.conf

server {
listen 80;
server_name www.ctnrs.com;
location / {
root /var/www/html;
index index.html;
}
}

.YAML语法
? 缩进表示层级关系
? 不支持制表符“tab”缩进,使用空格缩进
? 通常开头缩进 2 个空格
? 字符后缩进 1 个空格,如冒号、逗号等
? “---” 表示YAML格式,一个文件的开始
? “#”注释
playbook帮助 ansible-playbook --help
在执行前可以先检查语法ansible-playbook nginx.yml --syntax-check
.Playbook文件结构

  • name: play1
    hosts: webservers
    remote_user: root
    vars:
    var_name: value
    tasks:

    • name: echo
      shell: "echo {{var_name}}"
  • name: play2
    hosts: webservers
    remote_user: root
    vars:
    var_name: value
    tasks:

    • name: echo
      shell: "echo {{var_name}}"

  • hosts: webservers
    remote_user: root
    vars:
    var_name: value
    tasks:
    • name: echo
      shell: "echo {{var_name}}"

.在变更时执行操作(handlers)
notify:在任务结束时触发
handlers:由特定条件触发Tasks

hosts: webservers
gather_facts: no

tasks:

  • name: Copy nginx configuration file
    copy:
    src: ./site.conf
    dest: /etc/nginx/conf.d/site.conf
    notify:

    • reload nginx ------》当配置文件改变时通知重启nginx服务

    handlers:

    • name: reload nginx
      service: name=nginx state=reloaded

.任务控制(tags)
在每一个任务中添加tags标签,可以根据指定的tags运行相应的任务。

  • hosts: webservers
    gather_facts: no
    vars:
    hello: Ansible

    tasks:

    • name: Add repo
      yum_repository:
      name: nginx
      description: nginx repo
      baseurl: http://nginx.org/packages/centos/2/$basearch/
      gpgcheck: no
      enabled: 1
    • name: Install nginx
      yum:
      name: nginx
      state: latest
      tags: install
    • name: Copy nginx configuration file
      copy:
      src: ./site.conf
      dest: /etc/nginx/conf.d/site.conf
      tags: congiuration
    • name: Start nginx
      service:
      name: nginx
      state: started
    • name: Create wwwroot directory
      file:
      dest: /var/www/html
      state: directory
    • name: Create test page index.html
      shell: echo "hello {{hello}}" > /var/www/html/index.html
      指定tags运行:
      [[email protected] ansible-playbook]# ansible-playbook nginx.yml --tags "congiuration"

PLAY [webservers] ***

TASK [Copy nginx configuration file] ****
ok: [192.128.132.12]
ok: [192.128.132.14]

PLAY RECAP **
192.128.132.14 : ok=1 changed=0 unreachable=0 failed=0
192.128.132.12 : ok=1 changed=0 unreachable=0 failed=0

.Playbook文件调试
语法检查:ansible-playbook main.yml --syntax-check

打印语句:

  • hosts: webservers
    tasks:
    • debug:
      msg: {{group_names}}
    • debug:
      msg: {{inventory_hostname}}
    • debug:
      msg: {{ansible_hostname}}

.案例:自动部署Tomcat

  • hosts: 192.128.132.12
    gather_facts: no
    vars:
    tomcat_version: 8.1.33
    tomcat_install_dir: /usr/local

    tasks:

    • name: Install jdk1.8
      yum: name=java-1.8.0-openjdk state=present

    • name: Download tomcat
      get_url: url=http://mirrors.hust.edu.cn/apache/tomcat/tomcat-8/v{{ tomcat_version }}/bin/apache-tomcat-{{ tomcat_version }}.tar.gz dest=/tmp

    • name: Unarchive tomcat-{{ tomcat_version }}.tar.gz
      unarchive:
      src: /tmp/apache-tomcat-{{ tomcat_version }}.tar.gz
      dest: "{{ tomcat_install_dir }}"
      copy: no

    • name: Start tomcat
      shell: cd {{ tomcat_install_dir }} &&
      mv apache-tomcat-{{ tomcat_version }} tomcat8 &&
      cd tomcat8/bin && nohup ./startup.sh &

第 2 章 Playbook定义变量与使用

.命令行
.在Inventory中定义
.在Playbook中定义

在Playbook中定义变量


hosts: webservers
gather_facts: no
vars:
var_name: value
var_name: value
tasks:

  • name: hello
    shell: "echo {{var_name}}"

.在Role中定义
.注册变量(register)

注册变量


  • hosts: webservers
    gather_facts: no
    tasks:
    • name: Get date
      command: date +"%F_%T"
      register: date_output
    • name: Echo date_output
      command: touch /tmp/{{date_output.stdout}}

.系统信息变量(facts)

系统变量


hosts: webservers
tasks:

  • name: Get hostname
    debug: msg={{ansible_hostname}}

    第 3 章 Playbook文件复用

    .include & import 区别
    include(动态):在运行时导入
    ? --list-tags,--list-tasks不会显示到输出
    ? 不能使用notify触发来自include
    内处理程序名称(handlers)

import*(静态):在Playbook解析时预先导入
? 不能与循环一起使用
? 将变量用于目标文件或角色名称时,不能使用inventory(主机/主机组等)中的变量

import_playbook
技术图片

includetasks & importtasks
技术图片

4. 第 4 章 Playbook流程控制

条件

  • hosts: webservers

    tasks:

    • name: Host 192.168.132.16 run this task
      debug: msg="{{ansible_default_ipv4.address}}"
      when: ansible_default_ipv4.address == ‘192.168.132.16‘
      只执行该任务,跳过其他主机。

根据不同发行版安装apache服务

  • hosts: webservers

    tasks:

    • name: Update apache version - yum
      yum: name=httpd state=present
      when: ansible_pkg_mgr == ‘yum‘
      notify: restart httpd

    • name: Update apache version - apt
      apt: name=apache2 state=present update_cache=yes
      when: ansible_pkg_mgr == ‘apt‘
      notify: restart apache2

    handlers:

    • name: restart httpd
      service: name=httpd state=restared
      handlers:
    • name: restart apache2
      service: name=apache2 state=restared
      tasks:
  • name: "shut down CentOS 6 and Debian 7 systems"
    command: /sbin/shutdown -t now
    when: (ansible_distribution == "CentOS" and ansible_distribution_major_version == "6") or
    (ansible_distribution == "Debian" and ansible_distribution_major_version == "7")
    tasks:
    • name: "shut down CentOS 6 systems"
      command: /sbin/shutdown -t now
      when:
      • ansible_distribution == "CentOS"
      • ansible_distribution_major_version == "6"

循环

  • name: with_list
    debug:
    msg: "{{ item }}"
    with_list:

    • one
    • two
  • name: with_list -> loop
    debug:
    msg: "{{ item }}"
    loop:
    • one
    • two
  • name: with_items
    debug:
    msg: "{{ item }}"
    with_items: "{{ items }}"

  • name: with_items -> loop
    debug:
    msg: "{{ item }}"
    loop: "{{ items|flatten(levels=1) }}"
    创建用户:
  • hosts: webservers
    gather_facts: no
    tasks:
    • name: with_list
      user: name={{item}} state=present
      with_list:
      • test1
      • test2

        5. 第 5 章 Playbook模板(jinja2)

        5.1 .条件和循环

        test.yml


  • hosts: webservers
    vars:
    hello: Ansible

    tasks:

    • template: src=f.j2 dest=/tmp/f.j2

f.j2

{% set list=[‘one‘, ‘two‘, ‘three‘] %}

{% for i in list %}
{% if i == ‘two‘ %}
-> two
{% elif loop.index == 3 %}
-> 3
{% else %}
{{i}}
{% endif %}
{% endfor %}

{{ hello }}
{% set dict={‘zhangsan‘: ‘26‘, ‘lisi‘: ‘25‘} %}
{% for key, value in dict.iteritems() %}
{{key}} -> {{value}}
{% endfor %}

5.2 .案例:管理Nginx配置文件

main.yml


  • hosts: webservers
    gather_facts: no
    vars:
    http_port: 80
    server_name: www.ctnrs.com

    tasks:

    • name: Copy nginx configuration file
      template: src=site.conf.j2 dest=/etc/nginx/conf.d/www.ctnrs.com.conf
      notify: reload nginx

    handlers:

    • name: reload nginx
      service: name=nginx state=reloaded

site.conf.j2

{% set list=[10, 12, 13, 25, 31] %}
upstream {{server_name}} {
{% for i in list %}
server 192.168.1.{{i}}:80;
{% endfor %}
}
server {
listen {{ http_port }};
server_name {{ server_name }};

location / {
    proxy_pass http://{{server_name}};
} 

}

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