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
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
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