一、利用循环迭代任务

1️⃣：Ansible支持使用loop关键字对一组项目迭代任务，可以配置循环以利用列表中的各个项目、列表中各个文件的内容、生成的数字序列或更为复杂的结构来重复任务

1、简单循环

1️⃣：简单循环对一组项目迭代任务。loop关键字添加到任务中，将应对其迭代任务的项目列表取为值。循环变量item保存每个迭代过程中使用的值

  • 演示实例：

     //查看playbook
    
[root@localhost project]# cat playbook.yaml
    
---
    
- hosts: all
    
  tasks:
    
    - name: create user
    
      user:
    
        name: "{{ item }}"
    
        state: present
    
      loop:
    
        - zhangsan
    
        - lisi

 //测试执行play
    
[root@localhost project]# ansible-playbook playbook.yaml -C

PLAY [all] ****************************************************************************************************************************************************************

TASK [Gathering Facts] ****************************************************************************************************************************************************
    
ok: [client.example.com]

TASK [create user] ********************************************************************************************************************************************************
    
changed: [client.example.com] => (item=zhangsan)
    
changed: [client.example.com] => (item=lisi)

PLAY RECAP ****************************************************************************************************************************************************************
    
client.example.com         : ok=2    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

2️⃣：此外、还可以通过变量给loop提供所使用的的列表

  • 演示实例：

     //查看playbook
    
[root@localhost project]# cat playbook.yaml
    
---
    
- hosts: all
    
  vars:
    
    users:
    
      - zhangsan
    
      - lisi
    
      - wangwu
    
  tasks:
    
    - name: create user
    
      user:
    
        name: "{{ item }}"
    
        state: present
    
      loop: "{{ users }}"

 //执行play
    
[root@localhost project]# ansible-playbook playbook.yaml -C

PLAY [all] ****************************************************************************************************************************************************************

TASK [Gathering Facts] ****************************************************************************************************************************************************
    
ok: [client.example.com]

TASK [create user] ********************************************************************************************************************************************************
    
changed: [client.example.com] => (item=zhangsan)
    
changed: [client.example.com] => (item=lisi)
    
changed: [client.example.com] => (item=wangwu)

PLAY RECAP ****************************************************************************************************************************************************************
    
client.example.com         : ok=2    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

2、循环散列或字典列表

1️⃣： loop列表不需要是简单值列表

  • 演示实例：item标识一个循环的项目（任务），item.name和item.group表示item的两个键值（键值可自定义，但必须与loop中的项目匹配）

     //查看playbook文件
    
[root@localhost project]# cat playbook.yaml
    
---
    
- hosts: all
    
  tasks:
    
    - name: create user
    
      user:
    
        name: "{{ item.name }}"
    
        group: "{{ item.group}}"
    
        state: present
    
      loop:
    
        - name: zhangsan
    
          group: zhangsan
    
        - name: lisi
    
          group: lisi

 //测试是否可play
    
[root@localhost project]# ansible-playbook playbook.yaml -C

PLAY [all] ****************************************************************************************************************************************************************

TASK [Gathering Facts] ****************************************************************************************************************************************************
    
ok: [client.example.com]

TASK [create user] ********************************************************************************************************************************************************
    
changed: [client.example.com] => (item={'name': 'zhangsan', 'group': 'zhangsan'})
    
changed: [client.example.com] => (item={'name': 'lisi', 'group': 'lisi'})

PLAY RECAP ****************************************************************************************************************************************************************
    
client.example.com         : ok=2    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

3、将Register变量于Loop一起使用

  • 演示实例：

     //查看playbook
    
[root@localhost project]# cat playbook.yaml
    
---
    
- hosts: all
    
  tasks:
    
    - name: show some user
    
      shell: 'echo this user is {{ item }}'
    
      loop:
    
        - zhangsan
    
        - lisi
    
        - wangwu
    
      register: result

    - name: show these user
    
      debug:
    
        var: result

 //测试是否执行play
    
[root@localhost project]# ansible-playbook playbook.yaml -C

PLAY [all] ****************************************************************************************************************************************************************

TASK [Gathering Facts] ****************************************************************************************************************************************************
    
ok: [client.example.com]

TASK [show some user] *****************************************************************************************************************************************************
    
skipping: [client.example.com] => (item=zhangsan)
    
skipping: [client.example.com] => (item=lisi)
    
skipping: [client.example.com] => (item=wangwu) 

TASK [show these user]
    
............
    
"item": "zhangsan",
    
                "msg": "skipped, running in check mode",
    
                "skipped": true
    
............
    
"item": "lisi",
    
                "msg": "skipped, running in check mode",
    
                "skipped": true
    
.............
    
"item": "wangwu",
    
                "msg": "skipped, running in check mode",
    
                "skipped": true
    
.............

1️⃣： 在上面的例子中，results键包含一个列表。在下面，修改了playbook，使第二个任务迭代此列表

  • 演示实例：

     //查看playbook
    
[root@localhost project]# cat playbook.yaml
    
---
    
- hosts: all
    
  tasks:
    
    - name: show some user
    
      shell: 'echo this user is {{ item }}'
    
      loop:
    
        - zhangsan
    
        - lisi
    
        - wangwu
    
      register: magic

    - name: show these user
    
      debug:
    
        msg: "{{ item.stdout }}"
    
      loop: "{{ magic['results'] }}"

 //执行play
    
[root@localhost project]# ansible-playbook playbook.yaml

PLAY [all] ****************************************************************************************************************************************************************

TASK [Gathering Facts] ****************************************************************************************************************************************************
    
ok: [client.example.com]

TASK [show some user] *****************************************************************************************************************************************************
    
changed: [client.example.com] => (item=zhangsan)
    
changed: [client.example.com] => (item=lisi)
    
changed: [client.example.com] => (item=wangwu)

TASK [show these user] ****************************************************************************************************************************************************
    
ok: [client.example.com] => (item={'cmd': 'echo this user is zhangsan', 'stdout': 'this user is zhangsan', 'stderr': '', 'rc': 0, 'start': '2020-09-03 15:28:50.767109', 'end': '2020-09-03 15:28:50.774188', 'delta': '0:00:00.007079', 'changed': True, 'invocation': {'module_args': {'_raw_params': 'echo this user is zhangsan', '_uses_shell': True, 'warn': True, 'stdin_add_newline': True, 'strip_empty_ends': True, 'argv': None, 'chdir': None, 'executable': None, 'creates': None, 'removes': None, 'stdin': None}}, 'stdout_lines': ['this user is zhangsan'], 'stderr_lines': [], 'failed': False, 'item': 'zhangsan', 'ansible_loop_var': 'item'}) => {
    
    "msg": "this user is zhangsan"
    
}
    
ok: [client.example.com] => (item={'cmd': 'echo this user is lisi', 'stdout': 'this user is lisi', 'stderr': '', 'rc': 0, 'start': '2020-09-03 15:28:51.542241', 'end': '2020-09-03 15:28:51.547953', 'delta': '0:00:00.005712', 'changed': True, 'invocation': {'module_args': {'_raw_params': 'echo this user is lisi', '_uses_shell': True, 'warn': True, 'stdin_add_newline': True, 'strip_empty_ends': True, 'argv': None, 'chdir': None, 'executable': None, 'creates': None, 'removes': None, 'stdin': None}}, 'stdout_lines': ['this user is lisi'], 'stderr_lines': [], 'failed': False, 'item': 'lisi', 'ansible_loop_var': 'item'}) => {
    
    "msg": "this user is lisi"
    
}
    
ok: [client.example.com] => (item={'cmd': 'echo this user is wangwu', 'stdout': 'this user is wangwu', 'stderr': '', 'rc': 0, 'start': '2020-09-03 15:28:52.292883', 'end': '2020-09-03 15:28:52.298768', 'delta': '0:00:00.005885', 'changed': True, 'invocation': {'module_args': {'_raw_params': 'echo this user is wangwu', '_uses_shell': True, 'warn': True, 'stdin_add_newline': True, 'strip_empty_ends': True, 'argv': None, 'chdir': None, 'executable': None, 'creates': None, 'removes': None, 'stdin': None}}, 'stdout_lines': ['this user is wangwu'], 'stderr_lines': [], 'failed': False, 'item': 'wangwu', 'ansible_loop_var': 'item'}) => {
    
    "msg": "this user is wangwu"
    
}

PLAY RECAP ****************************************************************************************************************************************************************
    
client.example.com         : ok=3    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

二、有条件的运行任务

Ansible可使用conditionals在符合特定条件时执行任务或play。例如，可以利用一个条件在Ansible安装或配置服务前确定受管主机上的可用内存

1、条件任务语法

1️⃣：when语句用于有条件地运行任务；它取要测试的条件为值。如果条件满足，则运行任务。如果条件不满足，则跳过任务

  • 演示实例：

     //查看playbook
    
[root@localhost project]# cat playbook.yaml
    
---
    
- hosts: all
    
  vars:
    
    package: True
    
  tasks:
    
    - name: install httpd
    
      yum:
    
        name: httpd
    
        state: installed
    
      when: package

 //测试执行play
    
[root@localhost project]# ansible-playbook playbook.yaml 

PLAY [all] ****************************************************************************************************************************************************************

TASK [Gathering Facts] ****************************************************************************************************************************************************
    
ok: [client.example.com]

TASK [install httpd] ******************************************************************************************************************************************************
    
changed: [client.example.com]

PLAY RECAP ****************************************************************************************************************************************************************
    
client.example.com         : ok=2    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

2️⃣：处理条件时可使用的一些运算示例：

操作 示例
等于（值为字符串） ansible_machine == "x86_64"
等于（值为数字） max_memory == 512
小于 min_memory < 128
大于 min_memory > 256
小于等于 min_memory <= 256
大于等于 min_memory >= 512
不等于 min_memory != 512
变量存在 min_memory is defined
变量不存在 min_memory is not defined
布尔变量是True。1、True或yes的求值为True memory_available
布尔变量是False。0、False或no的求值为False not memory_available
第一个变量的值存在，作为第二个变量的列表中的值 ansible_distribution in supported_distros
  • 演示实例一：

     //查看playbook
    
[root@localhost project]# cat playbook.yaml
    
---
    
- hosts: all
    
  vars:
    
    package: httpd
    
  tasks:
    
    - name: install {{ package }}
    
      yum:
    
        name: "{{ package }}"
    
        state: present
    
      when: package is defined

 //执行play
    
[root@localhost project]# ansible-playbook playbook.yaml 

PLAY [all] ****************************************************************************************************************************************************************

TASK [Gathering Facts] ****************************************************************************************************************************************************
    
ok: [client.example.com]

TASK [install httpd] ******************************************************************************************************************************************************
    
changed: [client.example.com]

PLAY RECAP ****************************************************************************************************************************************************************
    
client.example.com         : ok=2    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
  • 演示实例二：第一个变量的值存在（一般是事实），且作为第二个变量列表中的值

     //查看playbook
    
[root@localhost project]# cat playbook.yaml
    
---
    
- hosts: all
    
  vars:
    
    version:
    
      - RedHat
    
      - CentOS
    
  tasks:
    
    - name: install httpd
    
      yum:
    
        name: httpd
    
        state: present
    
      when: ansible_facts['distribution'] in version     //ansible_facts['distribution']该变量的值与versionversion中的值匹配

 //执行play
    
[root@localhost project]# ansible-playbook playbook.yaml 

PLAY [all] ****************************************************************************************************************************************************************

TASK [Gathering Facts] ****************************************************************************************************************************************************
    
ok: [client.example.com]

TASK [install httpd] ******************************************************************************************************************************************************
    
changed: [client.example.com]

PLAY RECAP ****************************************************************************************************************************************************************
    
client.example.com         : ok=2    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
  • 演示实例三：（判断大小）

     //查看playbook
    
[root@localhost project]# cat playbook.yaml
    
---
    
- hosts: all
    
  vars:
    
    number: 800
    
  tasks:
    
    - name: install httpd
    
      yum:
    
        name: httpd
    
        state: present
    
      when: number >= 800

 //执行play
    
[root@localhost project]# ansible-playbook playbook.yaml 

PLAY [all] ****************************************************************************************************************************************************************

TASK [Gathering Facts] ****************************************************************************************************************************************************
    
ok: [client.example.com]

TASK [install httpd] ******************************************************************************************************************************************************
    
changed: [client.example.com]

PLAY RECAP ****************************************************************************************************************************************************************
    
client.example.com         : ok=2    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

2、测试多个条件

1️⃣：一个when语句可用于评估多个条件：使用and和or关键字组合条件，并使用括号分组条件

2️⃣：使用and语句运算时，两个条件必须为真，才能满足整个条件语句

  • 演示实例一：and 语句第一种写法

     //查看playbook
    
[root@localhost project]# cat playbook.yaml
    
---
    
- hosts: all
    
  tasks:
    
    - name: install httpd
    
      yum:
    
        name: httpd
    
        state: present
    
      when: ansible_facts['distribution_version'] == "8.1" and ansible_facts['distribution'] == "RedHat"

 //执行play
    
[root@localhost project]# ansible-playbook playbook.yaml 

PLAY [all] ****************************************************************************************************************************************************************

TASK [Gathering Facts] ****************************************************************************************************************************************************
    
ok: [client.example.com]

TASK [install httpd] ******************************************************************************************************************************************************
    
changed: [client.example.com]

PLAY RECAP ****************************************************************************************************************************************************************
    
client.example.com         : ok=2    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
  • 演示实例二：and 语句第二种写法

     //查看playbook
    
[root@localhost project]# cat playbook.yaml
    
---
    
- hosts: all
    
  tasks:
    
    - name: install httpd
    
      yum:
    
        name: httpd
    
        state: present
    
      when:
    
        - ansible_facts['distribution_version'] == "8.1"
    
        - ansible_facts['distribution'] == "RedHat"

 //执行play
    
[root@localhost project]# ansible-playbook playbook.yaml 

PLAY [all] ****************************************************************************************************************************************************************

TASK [Gathering Facts] ****************************************************************************************************************************************************
    
ok: [client.example.com]

TASK [install httpd] ******************************************************************************************************************************************************
    
changed: [client.example.com]

PLAY RECAP ****************************************************************************************************************************************************************
    
client.example.com         : ok=2    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
  • 演示实例三：and 语句第三中写法

     //查看playbook
    
[root@localhost project]# cat playbook.yaml
    
---
    
- hosts: all
    
  tasks:
    
    - name: install httpd
    
      yum:
    
        name: httpd
    
        state: present
    
      when:
    
        ( ansible_facts['distribution_version'] == "8.1" )
    
        and
    
        ( ansible_facts['distribution'] == "RedHat" )

 //执行play
    
[root@localhost project]# ansible-playbook playbook.yaml

PLAY [all] ****************************************************************************************************************************************************************

TASK [Gathering Facts] ****************************************************************************************************************************************************
    
ok: [client.example.com]

TASK [install httpd] ******************************************************************************************************************************************************
    
changed: [client.example.com]

PLAY RECAP ****************************************************************************************************************************************************************
    
client.example.com         : ok=2    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

3️⃣：使用or语句时，其中任一条件为真时，就能满足条件语句

  • 演示实例一：or 语句第一种写法

     //查看playbook
    
[root@localhost project]# cat playbook.yaml
    
---
    
- hosts: all
    
  tasks:
    
    - name: install httpd
    
      yum:
    
        name: httpd
    
        state: present
    
      when: ansible_facts['distribution'] == "RedHat" or ansible_facts['distribution_version'] == "7.9"

 //执行play
    
[root@localhost project]# ansible-playbook playbook.yaml 

PLAY [all] ****************************************************************************************************************************************************************

TASK [Gathering Facts] ****************************************************************************************************************************************************
    
ok: [client.example.com]

TASK [install httpd] ******************************************************************************************************************************************************
    
changed: [client.example.com]

PLAY RECAP ****************************************************************************************************************************************************************
    
client.example.com         : ok=2    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
    
 //我当前使用的是RHEL8.1版本
  • 演示实例二：or 语句第二种写法

    [root@localhost project]# cat playbook.yaml
    
---
    
- hosts: all
    
  tasks:
    
    - name: install httpd
    
      yum:
    
        name: httpd
    
        state: present
    
      when: >               //这里可以加，也可以不加；>：是允许下面的变量可以换行写
    
        ( ansible_facts['distribution'] == "RedHat" )
    
        or
    
        ( ansible_facts['distribution_version'] == "7.9 )"

 //执行play
    
[root@localhost project]# ansible-playbook playbook.yaml 

PLAY [all] ****************************************************************************************************************************************************************

TASK [Gathering Facts] ****************************************************************************************************************************************************
    
ok: [client.example.com]

TASK [install httpd] ******************************************************************************************************************************************************
    
changed: [client.example.com]

PLAY RECAP ****************************************************************************************************************************************************************
    
client.example.com         : ok=2    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0
  • 演示实例三：or 语句的第三种写法（与and语句嵌套使用）

     //查看playbook
    
[root@localhost project]# cat playbook.yaml
    
---
    
- hosts: all
    
  tasks:
    
    - name: install httpd
    
      yum:
    
        name: httpd
    
        state: present
    
      when:
    
        ( ansible_facts['distribution'] == "RedHat" and ansible_facts['kernel'] == "4.18.0-147.el8.x86_64"  )
    
        or
    
        ( ansible_facts['distribution_version'] == "7.9" and ansible_facts['distribution_major_version'] == "7" )

 //执行play
    
[root@localhost project]# ansible-playbook playbook.yaml 

PLAY [all] ****************************************************************************************************************************************************************

TASK [Gathering Facts] ****************************************************************************************************************************************************
    
ok: [client.example.com]

TASK [install httpd] ******************************************************************************************************************************************************
    
changed: [client.example.com]

PLAY RECAP ****************************************************************************************************************************************************************
    
client.example.com         : ok=2    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

三、组合循环和有条件任务

1、使用Loop和When组合使用

  • 演示实例：

     //查看playbook
    
[root@localhost project]# cat playbook.yaml
    
---
    
- hosts: all
    
  tasks:
    
    - name: install httpd
    
      yum:
    
        name: httpd
    
        state: present
    
      loop: "{{ ansible_facts['mounts'] }}"
    
      when:
    
        - item.mount == "/"
    
        - item.size_available > 50000000000

 //执行paly
    
[root@localhost project]# ansible-playbook playbook.yaml 

PLAY [all] ****************************************************************************************************************************************************************

TASK [Gathering Facts] ****************************************************************************************************************************************************
    
ok: [client.example.com]

TASK [install httpd] ******************************************************************************************************************************************************
    
changed: [client.example.com] => (item={'mount': '/', 'device': '/dev/mapper/rhel-root', 'fstype': 'xfs', 'options': 'rw,seclabel,relatime,attr2,inode64,noquota', 'size_total': 53660876800, 'size_available': 51805659136, 'block_size': 4096, 'block_total': 13100800, 'block_available': 12647866, 'block_used': 452934, 'inode_total': 26214400, 'inode_available': 26178405, 'inode_used': 35995, 'uuid': '6a525cf5-3f23-4639-81cb-04fcdb764eb6'})
    
skipping: [client.example.com] => (item={'mount': '/home', 'device': '/dev/mapper/rhel-home', 'fstype': 'xfs', 'options': 'rw,seclabel,relatime,attr2,inode64,noquota', 'size_total': 28922376192, 'size_available': 28686655488, 'block_size': 4096, 'block_total': 7061127, 'block_available': 7003578, 'block_used': 57549, 'inode_total': 14129152, 'inode_available': 14129137, 'inode_used': 15, 'uuid': '2840f839-89b2-4717-b1d0-c74c46d05019'})
    
skipping: [client.example.com] => (item={'mount': '/boot', 'device': '/dev/nvme0n1p1', 'fstype': 'xfs', 'options': 'rw,seclabel,relatime,attr2,inode64,noquota', 'size_total': 1063256064, 'size_available': 882565120, 'block_size': 4096, 'block_total': 259584, 'block_available': 215470, 'block_used': 44114, 'inode_total': 524288, 'inode_available': 523987, 'inode_used': 301, 'uuid': '234365dc-2262-452e-9cbb-a6acfde04385'})
    
skipping: [client.example.com] => (item={'mount': '/mnt', 'device': '/dev/sr0', 'fstype': 'iso9660', 'options': 'ro,relatime,nojoliet,check=s,map=n,blocksize=2048', 'size_total': 7851202560, 'size_available': 0, 'block_size': 2048, 'block_total': 3833595, 'block_available': 0, 'block_used': 3833595, 'inode_total': 0, 'inode_available': 0, 'inode_used': 0, 'uuid': '2019-10-15-13-34-03-00'}) 

PLAY RECAP ****************************************************************************************************************************************************************
    
client.example.com         : ok=2    changed=1    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

2、使用Register和When组合使用

  • 演示实例：

     //查看playbook
    
[root@localhost project]# cat playbook.yaml
    
---
    
- hosts: all
    
  tasks:
    
    - name: install httpd
    
      yum:
    
        name: httpd
    
        state: present
    
      ignore_errors: yes       //在运行时，如果出现错误且命令失败，将不会停止，继续执行其他的命令
    
      register: result       //将安装成功后的结果注册到result变量中

    - name: start httpd
    
      service:
    
        name: httpd
    
        state: started
    
      when: result.rc == 0    //在该变量中匹配到返回值rc=0执行该命令

 //执行play
    
[root@localhost project]# ansible-playbook playbook.yaml 

PLAY [all] ****************************************************************************************************************************************************************

TASK [Gathering Facts] ****************************************************************************************************************************************************
    
ok: [client.example.com]

TASK [install httpd] ******************************************************************************************************************************************************
    
changed: [client.example.com]

TASK [start httpd] ********************************************************************************************************************************************************
    
changed: [client.example.com]

PLAY RECAP ****************************************************************************************************************************************************************
    
client.example.com         : ok=3    changed=2    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

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