自动化运维Ansible实践

Posted 2021-11-26

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

includetasks & importtasks

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}};
} 

}