Ansible_编写循环和条件任务
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
下一篇：实施处理程序
