Ansible系列基础篇 1.7.2、PlayBook之循环
一、循环定义
循环可迭代对象，重复处理每条信息。
基础示例：
---
- hosts: test70
remote_user: root
gather_facts: no
tasks:
- debug:
msg: "{{item}}"
with_items:
- 1
- 2
- 3
# 也可以 with_items: [1,2,3]
使用内置变量循环，示例如下：
---
- hosts: test70
remote_user: root
gather_facts: no
tasks:
- debug:
msg: "{{item}}"
with_items: "{{groups.ungrouped}}"
复杂字段的循环，示例如下：
---
- hosts: test70
remote_user: root
gather_facts: no
tasks:
- debug:
msg: "{{item.test1}}"
with_items:
- { test1: a, test2: b }
- { test1: c, test2: d }
循环结果的存储与读取，通过register，把模块执行的结果存储到变量中，命令的结果，以列表形式存在returnvalue.results，示例如下：
---
- hosts: test70
gather_facts: no
tasks:
- shell: "{{item}}"
with_items:
- "ls /opt"
- "ls /home"
register: returnvalue
- debug:
msg: "{{item.stdout}}"
with_items: "{{returnvalue.results}}"
二、循环特殊关键字
2.1、with_list
当处理单层的简单列表时，with_list与with_items没有任何区别，只有在处理上例中的"嵌套列表"时，才会体现出区别，区别就是，with_items会将嵌套在内的小列表"拉平"，拉平后循环处理所有元素，而with_list则不会"拉平"嵌套的列表，with_list只会循环的处理列表（最外层列表）中的每一项。
with_items的嵌套的列表（序列中的序列），示例如下：
# 结果为 1, 2, 3, a, b
# 每个循环的列表项，也展开
---
- hosts: test70
remote_user: root
gather_facts: no
tasks:
- debug:
msg: "{{item}}"
with_items:
- [ 1, 2, 3 ]
- [ a, b ]
使用with_list：
# 结果为 [1, 2, 3], [a, b]
# 外层列表循环，每个项的列表内容不循环
---
- hosts: test70
remote_user: root
gather_facts: no
tasks:
- debug:
msg: "{{item}}"
with_list:
- [ 1, 2, 3 ]
- [ a, b ]
2.2、with_flattened
该关键字与with_items效果完全相同
2.3、with_together
两列表一一对应聚合，示例如下：
# 结果为： [1, a], [2, b], [3, c]
---
- hosts: test70
remote_user: root
gather_facts: no
tasks:
- debug:
msg: "{{ item }}"
with_together:
- [ 1, 2, 3 ]
- [ a, b, c ]
如果两列表长度不一致，一一对应时，无数据的，用null补齐。
2.4、with_cartesian
示例需求：需要在目标主机的测试目录中创建a、b、c三个目录，这三个目录都有相同的子目录，它们都有test1和test2两个子目录。
linux命令实现：mkdir -p {a,b,c}/{test1,test2}
ansible实现，用到关键字 with_cartesian ，实现交叉循环，和笛卡尔乘积一样，示例如下：
代码结果：[a, test1], [a, test2], [b, test1], [b, test2], [c, test1], [c, test2]
---
- hosts: test70
remote_user: root
gather_facts: no
tasks:
- debug:
msg: "/testdir/testdir/{{ item.0 }}/{{ item.1 }}"
with_cartesian:
- [ a, b, c ]
- [ test1, test2 ]
2.5、with_indexed_items
功能“：在循环处理列表时为列表中的每一项添加"数字索引"，"索引"从0开始。
代码结果： [0, test1], [1, test2], [2, test3]
---
- hosts: test70
remote_user: root
gather_facts: no
tasks:
- debug:
msg: "index is : {{ item.0 }} , value is {{ item.1 }}"
with_indexed_items:
- test1
- test2
- test3
多嵌套时，展开情况：
实例一，结果：[0, test1], [1, test2], [2, test3], [3, test4], [4, test5]
---
- hosts: test70
remote_user: root
gather_facts: no
tasks:
- debug:
msg: "index is : {{ item.0 }} , value is {{ item.1 }}"
with_indexed_items:
- [ test1, test2 ]
- [ test3, test4, test5 ]
实例二，结果：[0, test1], [1, test2], [2, test3], [3, [test4, test5]]
当多加了一层嵌套以后，"with_indexed_items"并不能像"with_flattened"一样将嵌套的列表"完全拉平"，第二层列表中的项如果仍然是一个列表，"with_indexed_items"则不会拉平这个列表，而是将其当做一个整体进行编号。
---
- hosts: test70
remote_user: root
gather_facts: no
tasks:
- debug:
msg: "{{ item }}"
with_indexed_items:
- [ test1, test2 ]
- [ test3, [ test4, test5 ] ]
2.6、with_sequence
功能：按照数字递增\递减方式，进行循环。
实例结果：1, 2, 3, 4, 5
---
- hosts: test70
remote_user: root
gather_facts: no
tasks:
- debug:
msg: "{{ item }}"
with_sequence: start=1 end=5 stride=1
下例中count=5表示数字序列默认从1开始，到5结束，默认步长为1，效果与上例相同。
---
- hosts: test70
remote_user: root
gather_facts: no
tasks:
- debug:
msg: "{{item}}"
with_sequence: count=5
下例执行结果：6, 4 ,2
---
- hosts: test70
remote_user: root
gather_facts: no
tasks:
- debug:
msg: "{{item}}"
with_sequence: start=6 end=2 stride=-2
格式化数据：
---
- hosts: test70
remote_user: root
gather_facts: no
tasks:
- debug:
msg: "{{item}}"
with_sequence: start=2 end=6 stride=2 format="number is %0.2f"
2.7、with_random_choice
功能：从列表的多个值中随机返回一个值。
---
- hosts: test70
remote_user: root
gather_facts: no
tasks:
- debug:
msg: "{{item}}"
with_random_choice:
- 1
- 2
- 3
- 4
- 5
2.8、with_dict
---
- hosts: test70
remote_user: root
gather_facts: no
vars:
users:
alice: female
bob: male
tasks:
- debug:
msg: "{{item}}"
with_dict: "{{users}}"
示例执行结果：
TASK [debug] *************************************
ok: [test70] => (item={'value': u'male', 'key': u'bob'}) => {
"changed": false,
"item": {
"key": "bob",
"value": "male"
},
"msg": {
"key": "bob",
"value": "male"
}
}
ok: [test70] => (item={'value': u'female', 'key': u'alice'}) => {
"changed": false,
"item": {
"key": "alice",
"value": "female"
},
"msg": {
"key": "alice",
"value": "female"
}
}
with_dict具体使用方式如下：
--- - hosts: test70 remote_user: root gather_facts: no vars: users: alice: female bob: male tasks: - debug: msg: "User name: {{item.key}} , User's gender: {{item.value}} " with_dict: "{{users}}"
2.9、with_subelements
处理一个像上例中一样的复合结构的字典数据，在处理这个字典的同时，需要指定一个子元素，这个子元素的值必须是一个列表，之后，"with_subelements"会将子元素的列表中的每一项作为一个整体，将其他子元素作为一个整体，然后将两个整体组合成item。
---
- hosts: test70
remote_user: root
gather_facts: no
vars:
users:
- name: bob
gender: male
hobby:
- Skateboard
- VideoGame
- name: alice
gender: female
hobby:
- Music
tasks:
- debug:
msg: "{{ item }}"
with_subelements:
- "{{users}}"
- hobby
执行结果：
TASK [debug] ***********************************************************
ok: [test70] => (item=({u'gender': u'male', u'name': u'bob'}, u'Skateboard')) => {
"changed": false,
"item": [
{
"gender": "male",
"name": "bob"
},
"Skateboard"
],
"msg": [
{
"gender": "male",
"name": "bob"
},
"Skateboard"
]
}
ok: [test70] => (item=({u'gender': u'male', u'name': u'bob'}, u'VideoGame')) => {
"changed": false,
"item": [
{
"gender": "male",
"name": "bob"
},
"VideoGame"
],
"msg": [
{
"gender": "male",
"name": "bob"
},
"VideoGame"
]
}
ok: [test70] => (item=({u'gender': u'female', u'name': u'alice'}, u'Music')) => {
"changed": false,
"item": [
{
"gender": "female",
"name": "alice"
},
"Music"
],
"msg": [
{
"gender": "female",
"name": "alice"
},
"Music"
]
}
---
- hosts: test70
remote_user: root
gather_facts: no
vars:
users:
- name: bob
gender: male
hobby:
- Skateboard
- VideoGame
- name: alice
gender: female
hobby:
- Music
tasks:
- debug:
msg: "{{ item.0.name }} 's hobby is {{ item.1 }}"
with_subelements:
- "{{users}}"
- hobby
执行结果：
"msg": "bob 's hobby is Skateboard"
"msg": "bob 's hobby is VideoGame"
"msg": "alice 's hobby is Music"
2.10、with_file
功能：获取到这些文件的内容。
---
- hosts: test70
remote_user: root
gather_facts: no
tasks:
- debug:
msg: "{{ item }}"
with_file:
- /testdir/testdir/a.log
- /opt/testfile
2.11、with_fileglob
功能：匹配文件名称。
- 只会匹配指定目录中的文件，而不会匹配指定目录中的目录。
---
- hosts: test70
remote_user: root
gather_facts: no
tasks:
- debug:
msg: "{{ item }}"
with_fileglob:
- /testdir/*
# 这个列表中有两项，第一项表示匹配"/testdir"目录下的文件，第二项表示匹配"/opt"目录下，以"test"开头，以". 任意3个字符"结尾的文件，比如"testa.123"或者"testfile.yml"
---
- hosts: test70
remote_user: root
gather_facts: no
tasks:
- debug:
msg: "{{ item }}"
with_fileglob:
- /testdir/*
- /opt/test*.???
