自动化运维工具-Ansible之5-流程控制

自动化运维工具-Ansible之5-流程控制

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：

使用不同系统的时候，可以通过判断系统型号，来区分需要安装的软件包。
在nfs和rsync安装过程中，客户端服务器不需要推送配置文件，写多个play，影响效率。
在源码安装nginx的时候，执行第二遍就无法执行了，此时我们就可以使用判断验证是否安装过。

单条件

官方示例：

tasks:
  - name: "shut down Debian flavored systems"
    command: /sbin/shutdown -t now
    when: ansible_facts['os_family'] == "Debian"
    # 请注意，所有变量都可以直接用于条件语句中，而无需使用双大括号

使用when判断系统

- hosts: web_group
  tasks:
    - name: Install CentOS Httpd
      yum:
        name: httpd
        state: present
      when: ansible_distribution == "CentOS"

    - name: Install Ubuntu Httpd
      yum:
        name: apache2
        state: present
      when: ansible_distribution == "Ubuntu"

使用when判断系统版本

- hosts: web_group
  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'

使用注册变量对返回值进行判断

- hosts: web_group
  tasks:
    - name: Test php Rpm Install
      shell: "rpm -qa | grep php"
      register: check_php

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

多条件

使用list列表形式（只能表示并且\and\和）

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

使用小括号分组

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")

使用is match支持通配符

tasks:
  - name: Add Crontab
    cron:
      name: "backup"
      minute: "00"
      hour: "01"
      job: "/bin/sh /root/backup.sh &>/dev/null"
    when: ansible_fqdn is match 'web*'

多条件运算

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

示例

rsync服务端推送配置文件

[root@m01 ~]# cat > /root/rsyncd/rsyncd.yml <<EOF
- 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
        group: www
        recurse: yes
      when: ansible_hostname == "backup"

    - name: Start Rsyncd Server
      systemd:
        name: rsyncd
        state: started
      when: ansible_hostname == "backup"
EOF

rsync客户端推送脚本

[root@m01 ~]# cat > /root/rsyncd/rsync.yml <<EOF
- hosts: all
  tasks:
    - name: SCP Backup Shell
      copy:
        src: ./backup.sh
        dest: /root/backup.sh
      when: ansible_hostname is match "web*"
EOF

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

如果httpd服务已经启动，就重启

[root@m01 ~]# cat > /root/rsyncd/if.yml <<EOF
- 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
EOF

playbook循环语句

with_items列表循环

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

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

自定义变量列表循环

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

字典循环

- hosts: web_group
  tasks:
    - name: Create Groups
      group:
        name: "{{ item.name }}"
        gid: "{{ item.gid }}"
      with_items:
        - { name: www, gid: 666 }
        - { name: lhd, gid: 777 }
        - { name: dsb, gid: 888 }

- hosts: web_group
  tasks:
    - name: Create Users
      user:
        name: "{{ item.name }}"
        uid: "{{ item.uid }}"
        group: "{{ item.name }}"
        shell: "{{ item.shell }}"
        create_home: "{{ item.create_home }}"
      with_items:
        - { name: www, uid: 666, shell: "/sbin/nologin", create_home: no }
        - { name: lhd, uid: 777, shell: "/bin/bash", create_home: no }
        - { name: dsb, uid: 888, shell: "/bin/bash", create_home: yes }

- hosts: web_group
  tasks:
    - name: Copy Conf And Passwd
      copy:
        src: "{{ item.src }}"
        dest: "{{ item.dest }}"
        mode: "{{ item.mode }}"
      with_items:
        - { src: "./rsyncd.conf", dest: "/etc/rsyncd.conf", mode: "0644" }
        - { src: "./rsync.passwd", dest: "/etc/rsync.passwd", mode: "0600" }

playbook触发器 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。

示例

- hosts: web_group
  vars:
    - http_port: 8080
  tasks:
    - name: Install Http Server
      yum:
        name: httpd
        state: present

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

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

注意：

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。

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。

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。

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。

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，或不执行指定的任务。

打标签的方式

对task下面的一个name打一个标签
对task下面的一个name打多个标签
对task下面的多个name打一个标签

标签的使用

-t:执行指定的tag标签任务
--skip-tags:执行--skip-tags之外的标签任务

使用-t指定tag

- 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

#查看所有的标签（也可以查看该剧本有多少 hosts ）
[root@m01 ~]# ansible-playbook tag.yml --list-tags

#执行指定的tag标签任务
[root@m01 ~]# ansible-playbook tag.yml -t httpd_server

#执行多个指定的tag标签任务
[root@m01 ~]# ansible-playbook tag.yml -t install_httpd,confiure_httpd

#跳过指定的tag标签任务
[root@m01 ~]# ansible-playbook tag.yml --skip-tags httpd_server

playbook文件复用

在之前写playbook的过程中，多个playbook没有办法一键执行，可以使用playbook的功能include，来动态调用task任务列表。

准备被调用的剧本

[root@m01 ~]# mkdir tesk
[root@m01 ~]# cat > /root/tesk/task_install.yml <<EOF
- name: Install Http Server
  yum:
    name: httpd
    state: present
EOF

[root@m01 ~]# cat > /root/tesk/task_configure.yml <<EOF
- name: configure httpd server
  template:
    src: ./httpd.j2
    dest: /etc/httpd/conf/httpd.conf
  notify: Restart Httpd Server
EOF

[root@m01 ~]# cat > /root/tesk/task_start.yml <<EOF
- name: start httpd server
  service:
    name: httpd
    state: started
    enabled: yes
EOF

只调用task：include_tasks

[root@m01 ~]# cat > /root/tesk/task.yml <<EOF
- hosts: web_group
  vars:
    - http_port: 8080

  tasks:
    - include_tasks: task_install.yml
    - include_tasks: task_configure.yml
    - include_tasks: task_start.yml

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

调用整个task文件旧版：include

[root@m01 ~]# cat > /root/tesk/task.yml <<EOF
- include: httpd.yml
- include: nfs.yml
- include: rsync.yml
EOF

调用整个task文件新版：import_playbook

[root@m01 ~]# cat > /root/tesk/task.yml <<EOF
- import_playbook: httpd.yml
- import_playbook: nfs.yml
- import_playbook: rsync.yml
EOF

在saltstack中，叫做top file入口文件。

playbook忽略错误

默认playbook会检测task执行的返回状态，如果遇到错误则会立即终止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。

忽略错误：ignore_errors:yes

- hosts: web_group
  tasks:
    - name: Ignore False
      command: /bin/false
      ignore_errors: yes
	  
    - name: touch new file
      file:
        path: /tmp/oldboy.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。

当task执行失败时，可以使用force_handlers: yes，强制调用handler
当task执行成功时，可以使用changed_when: false，将change状态改为ok，显示为绿色

强制调用handler

- hosts: web_group
  vars:
    - http_port: 8080
  force_handlers: yes
  tasks:
    - name: config httpd server
      template:
        src: ./httpd.j2
        dest: /etc/httpd/conf/httpd.conf
      notify: 
        - Restart Httpd Server

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

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

- hosts: web_group
  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 }}

多条件抑制changed_when

- hosts: web_group
  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.stderr_lines[1] == "Syntax OK"
        - false

    - name: debug
      debug: msg={{ httpd_check.stderr_lines[1] }}

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

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

https://www.cnblogs.com/f-ck-need-u/p/7576137.html#ansible

posted @ 2021-01-02 18:18 原因与结果阅读(116) 评论(0) 编辑收藏举报

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原因与结果

自动化运维工具-Ansible之5-流程控制

自动化运维工具-Ansible之5-流程控制

playbook条件语句

单条件

多条件

多条件运算

示例

playbook循环语句

with_items列表循环

自定义变量列表循环

字典循环

playbook触发器 handlers

playbook任务标签

playbook文件复用

playbook忽略错误

playbook错误处理

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