Ansible--04 ansible 流程控制

ansible 流程控制

playbook 条件语句

不管是 shell 还是各大编程预言中，流程控制，条件判断都是必不可少的，在我们使用 Ansible 的过程中，条件判断的使用频率都非常高。

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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。

根据不同的操作系统安装apache

官方示例：

tasks:
  - name: "shut down Debian flavored systems"
    command: /sbin/shutdown -t now
    when: ansible_facts['os_family'] == "Debian"
    # note that all variables can be used directly in conditionals without double curly braces

示例： 根据不同的 系统安装不同的服务

- hosts: web_group
  tasks:
    - name: Install CentOS Htt
        state: present
    #官方
      when: ansible_facts['os_family'] == "CentOS"
    #非官方
      when: ansible_distribution == "CentOS"

    - name: Install Ubuntu Httpd
      yum:
        name: apache2
        state: present
      when: ansible_facts['os_family'] == "Ubuntu"

可以使用括号对条件进行分组

tasks:
  - name: "shut down CentOS 6 and Debian 7 systems"
    command: /sbin/shutdown -t now
    when: (ansible_facts['distribution'] == "CentOS" and ansible_facts['distribution_major_version'] == "6") or
          (ansible_facts['distribution'] == "Debian" and ansible_facts['distribution_major_version'] == "7")

可以指定多条件为列表

tasks:
  - name: "shut down CentOS 6 systems"
    command: /sbin/shutdown -t now
    when:
      - ansible_facts['distribution'] == "CentOS"
      - ansible_facts['distribution_major_version'] == "6"

条件运算

tasks:
  - shell: echo "only on Red Hat 6, derivatives, and later"
    when: ansible_facts['os_family'] == "RedHat" and ansible_facts['lsb']['major_release']|int >= 6

rsync服务端推送配置文件

[root@m01 ~]# cat rsyncd/rsyncd.yml
- hosts: rsync_server
  tasks:
    - name: Install Rsyncd Server
      yum:
        name: rsync
        state: present

    - name: Create www Group
      group:
        name: www

        gid: 666
    - name: Create www User
      user:
        name: www
        group: www
        uid: 666
        create_home: false
        shell: /sbin/nologin

    - name: Scp Rsync Config
      copy:
        src: ./rsyncd.j2
        dest: /etc/rsyncd.conf
        owner: root
        group: root
        mode: 0644
      when: ansible_hostname == "backup"

    - name: Create Passwd File
      copy:
        content: 'rsync_backup:123'
        dest: /etc/rsync.passwd
        owner: root
        group: root
        mode: 0600
      when: ansible_hostname == "backup"

    - name: Create backup Directory
      file:
        path: /backup
        state: directory
        mode: 0755
        owner: www
        name: rsyncd
        state: started
      when: ansible_hostname == "backup"

rsync客户端推送脚本

[root@m01 ~]# vim rsync.yml
- hosts: rsync_server
  tasks:
    - name: SCP Backup Shell
      copy:
        src: ./backup.sh
        dest: /root/backup.sh
      when: ansible_hostname is match "web*"

#执行结果
PLAY [rsync_server] **************************************************************************************************************************************************************************************************************************

TASK [Gathering Facts] ***********************************************************************************************************************************************************************************************************************
ok: [web02]
ok: [backup]
ok: [web01]

TASK [SCP Backup Shell] **********************************************************************************************************************************************************************************************************************
skipping: [backup]
changed: [web01]
changed: [web02]

PLAY RECAP ***********************************************************************************************************************************************************************************************************************************
backup                     : ok=1    changed=0    unreachable=0    failed=0    skipped=1    rescued=0    ignored=0
web01                      : ok=2    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
web02                      : ok=2    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

通过register将命令执行结果保存至变量，然后通过when 语句进行判断

- 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

使用when判断主机名

- hosts: rsync_server
  tasks:

    - name: Install rsyncd Server
      yum:
        name: rsync
        state: present

    - name: Config rsyncd Conf
      copy:
        src: ./rsyncd.j2
        dest: /etc/rsyncd.conf
        owner: root
        group: root
        mode: 0644
      when: ansible_fqdn == 'backup'

    - name: Create dir
      file:
        path: /backup
        state: directory
        owner: www
        group: www
        mode: 0755
        recurse: yes
      when: ansible_fqdn == 'backup'

    - name: Create passwd file
      copy:
        content: "rsync_backup:123"
        dest: /etc/rsync.passwd
        owner: root
        group: root
        mode: 0600
      when: ansible_fqdn == 'backup'

#单条件判断
    - name: Start rsyncd
      systemd:
        name: rsyncd
        state: started
        enabled: yes
      when: ansible_fqdn == 'backup'

#多条件判断，使用小括号分组
    - name: copy shell
      template:
        src: ./backup.sh
        dest: /root
      when: (ansible_fqdn == 'web01') or (ansible_fqdn == 'web02')

#多条件判断，使用list列表形式
    - name: copy shell
      template:
        src: ./backup.sh
        dest: /root
      when:
        - ansible_fqdn == 'web01'
        - ansible_fqdn == 'web02'

#多条件判断，使用is match 支持通配符
    - name: Add Crontab
      cron:
        name: "backup"
        minute: "00"
        hour: "01"
        job: "/bin/sh /root/backup.sh &>/dev/null"
      when: ansible_fqdn is match 'web*'

2.使用when判断系统

- hosts: webs
  tasks:
    - name: Install CentOS Apache
      yum:
        name: httpd
        state: present
      when: ansible_distribution == 'CentOS'

    - name: Install Ubuntu Apache
      apt:
        name: apache2
        state: present
      when: ansible_distribution == 'Ubuntu'

3.使用when判断系统版本

- hosts: webs
  tasks:
    - name: Start CentOS6 Httpd
      shell: "/etc/init.d/httpd start"
      when: ansible_distribution_major_version == '6'

    - name: Start CentOS7 Httpd
      shell: "systemctl start httpd"
      when: ansible_distribution_major_version == '7'

4.使用注册变量对返回值进行判断

    - name: pan duan rpm bao
      shell: "rpm -qa|grep php"
      register: check_php

    - name: Install php
      shell: "cd /usr/local/src && rpm -Uvh *rpm"
      when: check_php.rc != 0

playbook 循环语句

创建目录之类的操作，2个目录就要写两个file 模块来创建，如果有循环，可以减少重复性代码。

1.启动多个服务

- hosts: web_group
  tasks:
    - name: start service
      systemd:
        name: "{{ item }}"
        state: started
      with_items:
        - httpd
        - php-fpm
        - mariadb

2.定义变量循环

- name: ensure a list of packages installed
  yum:
    name: "{{ packages }}"
  vars:
    packages:
    - httpd
    - httpd-tools

- hosts: web_group
  tasks:
    - name: ensure a list of packages installed
      yum: name= "{{ item }}" state=present
      with_items:
        - httpd
        - httpd-tools

3.字典循环

拷贝文件

- hosts: web_group
  tasks:
    - name: copy conf and code
      copy:
        src: "{{ item.src }}"
        dest: "{{ item.dest }}"
        mode: "{{ item.mode }}"
      with_items:
        - { src: "./httpd.conf", dest: "/etc/httpd/conf/", mode: "0644" }
        - { src: "./upload_file.php", dest: "/var/www/html/", mode: "0600" }

    - name: tar php and nginx and wordpress
      unarchive:
        src: "{{ item.src }}"
        dest: "{{ item.dest }}"
        owner: "{{ item.user }}"
        group: "{{ item.user }}"
        copy: yes
      with_items:
        - { src: "./php.tgz", dest: "/usr/local/src", user: "root" }
        - { src: "./nginx-1.16.0.tar.gz", dest: "/root", user: "root" }
        - { src: "./wordpress.tgz", dest: "/code", user: "www" }

ansible handlers(触发器）

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。

实践案例：

    - name: scp nginx shell conf
      copy:
        src: "{{ item.src }}"
        dest: "{{ item.dest }}"
      with_items:
        - { src: "./nginx.service", dest: "/usr/lib/systemd/system" }
        - { src: "./nginx.conf", dest: "/usr/local/nginx/conf/" }
        - { src: "./www.drz.com.conf", dest: "/usr/local/nginx/conf/conf.d" }
      #添加触发器
      notify: reload nginx

  handlers:
    - name: reload nginx
      systemd:
        name: nginx
        state: reloaded

注意：

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

playbook任务标签

默认情 况下，Ansible 在执行一个playbook 时，会执行playbook中定义的所有任务，Ansible的标签 （tag）功能可以给单独任务甚至整个playbook 打上标签，然后利用这些标签来指定要运行playbook中的个别任务，或不执行制定的任务。

打标签的方式

1. 对一个task打一个标签
2. 对一个task打多个标签
3. 对多个task打一个标签

打完标签如何使用

-t : 指定的tag标签任务

--skip-tags : 执行--skip-tags之外的标签任务

使用 - t 指定 tag

[root@m01 m01]# cat tag.yml
- hosts: web_group
  vars:
    - http_port: 8080
  tasks:
    - name: Install Http Server
      yum:
        name: httpd
        state: present
      tags:
        - install_httpd
        - httpd_server

    - name: configure httpd server
      template:
        src: ./httpd.j2
        dest: /etc/httpd/conf/httpd.conf
      notify: Restart Httpd Server
      tags:
        - config_httpd
        - httpd_server

    - name: start httpd server
      service:
        name: httpd
        state: started
        enabled: yes
      tags: service_httpd

  handlers:
    - name: Restart Httpd Server
      systemd:
        name: httpd
        state: restarted 

[root@m01 m01]# ansible-playbook tag.yml --list-tags
[root@m01 m01]# ansible-playbook tag.yml -t httpd_server
[root@m01 m01]# ansible-playbook tag.yml -t install_httpd,confiure_httpd
[root@m01 m01]# ansible-playbook tag.yml --skip-tags httpd_server

playbo ok复用include

在之前写playbook的过程中，写多个playbook没有办法一键执行，所以playbook 中有一个功能，叫做 include 用来动态调用task任务列表。

只调用task include_tasks

调用整个task 文件： include （新版本： import_playbook）

在saltstack中，叫做 top file入口文件。

示例：

[root@m01 web]# vim install_nginx.yml 

- name: Install nginx
  yum:
    name: nginx
    state: present

[root@m01 web]# vim conf_nginx.yml
- name: conf nginx
  copy:
    src: ./www.drz.com.conf
    dest: /etc/nginx/conf.d
  notify: reload nginx

[root@m01 web]# vim main.yml
- hosts:
  tasks:
    - include_tasks: ./install_nginx.yml
    - include_tasks: ./conf_nginx.yml
  handlers:
    - name: reload nginx
      systemd:
        name: nginx
        state: reloaded

2.直接复用写好的yml文件

• 旧版：include
• 新版：import_playbook

- import_playbook: ./lnmp.yml
- import_playbook: ../mariadb/mysql.yml

playbook 忽略错误

默认playbook会监测task 执行的返回状态，如果遇到错误则会立即中止playbook 的后续task执行，然而有些时候playbook 即使执行错误了也要让其继续执行。

加入参数： ignore_errors:yes 忽略错误

[root@m01 ~]# cat ignore.yml
---
- hosts: web_group
  tasks:
    - name: Ignore False
      command: /bin/false
      ignore_errors: yes

    - name: touch new file
      file:
        path: /tmp/zls.txt
        state: touch

playbook 错误处理

如上所述，当 task 执行失败时，playbook 将不再继续执行，包括如果在task中设置了handler 也不会被执行。

但是我们可以采取强制措施..

---

强制调用handler

[root@m01 ~]# cat handler.yml
- hosts: web_group
  vars:
    - http_port: 8080
  force_handlers: yes
  tasks:

    - name: config httpd server
      template:
        src: ./httpd.j2
        dest: /etc/httpd/conf
      notify:
        - Restart Httpd Server
        - Restart PHP Server

    - name: Install Http Server
      yum:
        name: htttpd
        state: present

    - name: start httpd server
      service:
        name:httpd
        state: started
        enabled: yes

  handlers:
    - name: Restart Httpd Server
      systemd:
        name: httpd
        state: restarted 

    - name: Restart PHP Server
      systemd:
        name: php-fpm
        state: restarted

抑制changed

被管理主机没有发生变化，可以使用参数将change状态改为ok

[root@m01 ~]# cat handler.yml
- hosts: web_group
  vars:
    - http_port: 8080
  force_handlers: yes
  tasks:
    - name: shell
      shell: netstat -lntup|grep httpd
      register: check_httpd
      changed_when: false

    - name: debug
      debug: msg={{ check_httpd.stdout.lines }}

[root@m01 project2]# cat changed_when.yml
- hosts: webservers
  vars:
    - http_port: 8080
  tasks:
    - name: configure httpd server
      template:
        src: ./httpd.j2
        dest: /etc/httpd/conf/httpd.conf
      notify: Restart Httpd Server

    - name: Check HTTPD
      shell: /usr/sbin/httpd -t
      register: httpd_check
      changed_when:
        - httpd_check.stdout.find('OK')
        - false

    - name: start httpd server
      service:
        name: httpd
        state: started
        enabled: yes

  handlers:
    - name: Restart Httpd Server
      systemd:
        name: httpd
        state: restarted