自动化运维工具-Ansible之5-流程控制

2022-01-28 17:20:44

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

码农公寓

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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