Ansible第五章 ansible中的任务执行控制

一.循环

循环迭代任务

1.简单循环

loop:
- value1            ##赋值列表
- value2
- ...
{{item}}         ##迭代变量名称

实例：
---
- name: create file
hosts: 172.25.0.254
tasks:
  - name: file module
    file:
      name: /mnt/{{item}}
      state: present
    loop:
      - westos_file1
      - westos_file2

 2.循环散列或字典列表

---
- name: create file
hosts: 172.25.0.254
tasks:
  - name: file module
    service:
      name: "{{ item.name}}"
      state: "{{ item.state }}"
    loop:
      - name: httpd
        state: started
      - name: vsftpd
        state: stopped

练习：

http://172.25.254.250/RHCE_EXAM/files/hwreport.empty
创建一个名为/home/devops/.ansible/hwreport.yaml 的playbook 它将在所在所有受管节点上含有以下信息的输出文件 /mnt/hwreport.txt 清单主机名称
以MB表示总内存大小
BIOS 版本
磁盘设备 vda 的大小
磁盘设备vdb的大小
输出文件中的每一行含有一个 key=value 对
将它保存到/mnt/hwreport.txt
使用正确的值改为 /mnt/hwreport.txt
如果硬件不存在，相关的值设为NONE

[devops@ansible .ansible]$ cat hwreport.yaml 
- name: hwreport
  hosts: westos
  tasks:
    - name: download
      get_url:
        url: http://172.25.254.250/RHCE_EXAM/files/hwreport.empty
        dest: /mnt/hwreport.txt
        force: yes

    - name: check device
      lineinfile:
        path: /mnt/hwreport.txt
        regexp: "{{item.start}}"
        line: "{{item.start}}={{item.reline}}"
      loop:
        - name: HOST
          reline: "HOST={{ansible_facts['fqdn']}}"
        - name: MEMERY
          reline: "{{ansible_facts['memtotal_mb']}}"
        - name: BIOS
          reline: "{{ansible_facts['bios_version']}}"
        - name: DISK_SIZE_VDA
          reline: "{{ansible_facts['devices']['vda']['size'] | default ('NONE')}}"
        - name: DISK_SIZE_VDB
          reline: "{{ansible_facts['devices']['vdb']['size'] | default ('NONE')}}"
            
[devops@ansible .ansible]$ ansible-playbook hwreport.yaml

 

在受控主机中查看：

[root@node1 mnt]# cat hwreport.txt 
# Hardware report
HOST=node1.westos.org
MEMERY=818
BIOS=1.11.1-4.module+el8.1.0+4066+0f1aadab
DISK_SIZE_VDA=20.00 GB
DISK_SIZE_VDB=7.86 GB
[root@node1 mnt]# 

二.条件

when:
- 条件1
- 条件2

条件判断：

=             value == "字符串",value == 数字
<             value < 数字
>              value > 数字
<=            value <= 数字
>=            value >= 数字
!=             value != 数字
is defined value        value is defined 变量存在
is not defined            value is not defined  变量不存在
in                                value is in value  变量为
not in                          value is not in value   变量不为
bool变量为true          value   value的值为true
bool变量为false         not value  value的值为false
                                      value in value2  value的值在value2列表中

[devops@ansible .ansible]$ cat checkfile.yaml
- name: check file
  hosts: westos
  tasks:
    - name: check file
      shell: test -e /mnt/test
      register: checkout
      ignore_errors: yes

    - name: debug
      debug:
        msg: "/mnt/test is not exist"
      when: checkout.rc != 0

    - name: debug
      debug:
        msg: "/mnt/test is  exist"
      when: checkout.rc == 0

[devops@ansible .ansible]$ ansible-playbook checkfile.yaml 

 

[devops@ansible .ansible]$ cat checkfile.yaml
- name: check file
  hosts: all
  tasks:
    - name: check file
      shell: test -e /mnt/test
      register: checkout
      ignore_errors: yes
      when: inventory_hostname in  groups.westos

    - name: debug
      debug:
        msg: "/mnt/test is not exist"
      when: 
        - inventory_hostname in  groups.westos
        - checkout.rc != 0

    - name: debug
      debug:
        msg: "/mnt/test is  exist"
      when: 
        - inventory_hostname in  groups.westos
        - checkout.rc == 0
[devops@ansible .ansible]$ ansible-playbook checkfile.yaml 

 

[devops@ansible .ansible]$ cat checkfile.yaml 
- name: check file
  hosts: all
  tasks:
    - name: check file
      shell: test -e /mnt/test
      register: checkout
      ignore_errors: yes
    
    - name: debug
      debug:
        msg: "/mnt/test is not exist {{checkout.rc}}"
      when:
        - checkout.rc 

    - name: debug
      debug:
        msg: "/mnt/test is  exist {{checkout.rc}}"
      when: 
        - not checkout.rc
[devops@ansible .ansible]$ ansible-playbook checkfile.yaml 

 

多条件组合

when:
条件1 and 条件2
- 条件1
- 条件2
when:

条件1 or 条件2
when: >
条件1
or
条件2

测试题:

建立playbook ~/ansibles/lvm.yml要求如下:
*建立大小为1500M名为exam_lvm的lvm 在westos组中
*如果westos不存在请输出:
vg westos is not exist
*如果westos大小不足1500M请输出:
vg westos is less then 1500M
并建立800M大小的lvm

三.触发器

notify: 触发器当遇到更改是触发handlers
handlers: 触发器触发后执行的动作
 

[devops@ansible .ansible]$ vim apache.yaml
- name: configure webserver
  hosts: westos
  tasks:
    - name: install httpd
      dnf:
        name: httpd
        state: present
    - name: configure httpd.conf
      lineinfile:
        path: /etc/httpd/conf/httpd.conf
        regexp: "^Listen"
        line: "Listen 8080"
      notify:
        restart httpd       ##当httpd.conf文件不做更改的时，不重启服务（会自动检测）
  handlers:
    - name: restart httpd
      service:
        name: httpd
        state: restarted
        enabled: yes
[devops@ansible .ansible]$ ansible-playbook apache.yaml 

四.处理失败任务

1.ignore_errors

作用:当play遇到任务失败是会终止
ignore_errors: yes        将会忽略任务失败使下面的任务继续运行

[devops@ansible .ansible]$ vim apache.yaml
- name: configure webserver
  hosts: westos
  tasks:
    - name: install httpd
      dnf:
        name: http
        state: present
      ignore_errors: yes

    - name: configure httpd.conf
      lineinfile:
        path: /etc/httpd/conf/httpd.conf
        regexp: "^Listen"
        line: "Listen 80"
      notify:
        restart httpd
  handlers:
    - name: restart httpd
      service:
        name: httpd
        state: restarted
        enabled: yes
[devops@ansible .ansible]$ ansible-playbook apache.yaml 

 2.force_handlers

作用:当任务失败后play被终止也会调用触发器进程

[devops@ansible .ansible]$ vim apache.yaml
[devops@ansible .ansible]$ cat apache.yaml 
- name: configure webserver
  hosts: westos
  force_handlers: yes
  tasks:
    - name: install httpd
      dnf:
        name: httpd
        state: present
      

    - name: configure httpd.conf
      lineinfile:
        path: /etc/httpd/conf/httpd.conf
        regexp: "^Listen"
        line: "Listen 8080"
      notify:
        restart httpd
    - name: install test  ##error
      dnf:
        name: test
        state: present

  handlers:
    - name: restart httpd
      service:
        name: httpd
        state: restarted
        enabled: yes
[devops@ansible .ansible]$ ansible-playbook apache.yaml 

 3.changed_when

作用:控制任务在何时报告它已进行更改

[devops@ansible .ansible]$ cat apache.yaml 
- name: configure webserver
  hosts: westos
  force_handlers: yes
  tasks:
    - name: install httpd
      dnf:
        name: httpd
        state: present  

    - name: configure httpd.conf
      lineinfile:
        path: /etc/httpd/conf/httpd.conf
        regexp: "^Listen"
        line: "Listen 8080"
      changed_when: yes   ##yes,表示已经做了更改（真实情况可能没有更改）,为no时，与真实情况一致
      notify:
        restart httpd

    - name: install test
      dnf:
        name: test
        state: present

  handlers:
    - name: restart httpd
      service:
        name: httpd
        state: restarted
        enabled: yes

 4.failed_when

当符合条件时强制任务失败

[devops@ansible .ansible]$ vim apache.yaml
[devops@ansible .ansible]$ cat apache.yaml 
- name: configure webserver
  hosts: westos
  force_handlers: yes
  tasks:
    - name: install httpd
      dnf:
        name: httpd
        state: present
      

    - name: configure httpd.conf
      lineinfile:
        path: /etc/httpd/conf/httpd.conf
        regexp: "^Listen"
        line: "Listen 8080"
      changed_when: no
      failed_when: yes           ##yes强制任务失败,no 和真实情况一致
      notify:
        restart httpd

    - name: install test
      dnf:
        name: test
        state: present

  handlers:
    - name: restart httpd
      service:
        name: httpd
        state: restarted
        enabled: yes
        
[devops@ansible .ansible]$ ansible-playbook apache.yaml 

 5.block

block:        ##定义要运行的任务
rescue:        ##定义当block句子中出现失败任务后运行的任务
always:         ##定义最终独立运行的任务

[devops@ansible .ansible]$ cat apache.yaml 
- name: configure webserver
  hosts: westos
  force_handlers: yes
  tasks:
    - name: test
      block:
         - name: test block
           debug:
             msg: block message
      rescue:
        - name: test block
          debug:
            msg: rescue message
      always:
        - name: test block
          debug:
            msg: always
~                            
[devops@ansible .ansible]$ ansible-playbook apache.yaml 

#测试练习#

建立playbook ~/westos.yml要求如下:
建立大小为1500M名为/dev/vdb1的设备
如果/dev/vdb不存在请输入:
/dev/vdb is not exist
如果/dev/vdb大小不足2G请输出:
/dev/vdb is less then 2G
并建立800M大小的/dev/vdb1
此设备挂载到/westos上

[devops@ansible .ansible]$ cat westos.yaml 
- name: create vdb1
  hosts: westos
  force_handlers: yes
  tasks:
    - name: check /dev/vdb
      debug: 
        msg: "vdb is not exist"
      when: ansible_facts['devices']['vdb'] is not defined

    - name: create /dev/vdb1
      block:
        - name: create 1500M
          parted:
            device: /dev/vdb
            number: 1
            state: present
            part_end: 1500MiB
      rescue:
        - name: create 800M
          parted:
            device: /dev/vdb
            number: 1
            state: present
            part_end: 800MiB
        - debug:
            msg: vdb is less then 1500M
      always:
        - name: create filesystem
          filesystem:
            fstype: xfs
            dev: /dev/vdb1
        - name: mkdir /westos
          file:
            path: /westos
            state: directory
        - name: mount /dev/vdb1
          mount:
            path: /westos
            src: /dev/vdb1
            fstype: xfs
            state: mounted
      when: ansible_facts['devicds']['vdb'] is defined

[devops@ansible .ansible]$ ansible-playbook westos.yaml