13. Ansible Playbook with_X循环语句
目录
循环语句
简介
我们在编写playbook的时候，不可避免的要执行一些重复性操作，比如指安装软件包，批量创建用户，操作某个目录下的所有文件等。正如我们所说，ansible一门简单的自动化语言，所以流程控制、循环语句这些编程语言的基本元素它同样都具备。
在Ansible 2.5以前，playbook通过不同的循环语句以实现不同的循环，这些语句使用with_作为前缀。这些语法目前仍然兼容，但在未来的某个时间点，会逐步废弃。
下面列出一些较常见的with_X循环语句：
with_items
with_flattened
with_list
with_together
with_nested
with_indexed_items
with_sequence
with_random_choice
with_dict
with_subelement
with_file
with_fileglob
with_lines
1. with_items
简单的列表循环
场景一： 循环打印inventory中所有未分组的主机
- hosts: test
gather_facts: no
tasks:
- debug:
msg: "{{ item }}""
with_items: "{{ groups.ungrouped }}"
场景二： 直接在with_items中定义被循环的列表
- hosts: test
gather_facts: no
tasks:
- name: "with_items"
debug:
msg: "{{ item }}"
with_items:
- "user0"
- "user1"
- "user2"
也可以写成如下方式：
- hosts: test
gather_facts: no
tasks:
- name: "with_items"
debug:
msg: "{{ item }}"
with_items: ["user0","user1","user2"]
场景三： 在with_items中定义更复杂的列表
- hosts: test
gather_facts: no
tasks:
- name: "create directory"
file:
path: "/{{ item.path1 }}/{{ item.path2 }}"
with_items:
- { path1: a, path2: b}
- { path1: c, path2: d}
2. with_list
与with_items一样，也是用于循环列表。区别是，如果列表的值也是列表，with_items会将第一层嵌套的列表拉平，而with_list会将值作为一个整体返回。
示例：
# 使用with_items的示例
- hosts: test
gather_facts: no
tasks:
- name: "with_items"
debug:
msg: "{{ item }}"
with_items:
- [1, 2]
- [a, b]
# 返回结果：
# ansible-playbook with_items_test.yml
PLAY [test] *****************************************************************************************************************************************************************
TASK [Gathering Facts] ******************************************************************************************************************************************************
ok: [10.1.61.187]
▽ASK [with_items] ***********************************************************************************************************************************************************
ok: [10.1.61.187] => (item=1) => {
"msg": 1
}
ok: [10.1.61.187] => (item=2) => {
"msg": 2
}
ok: [10.1.61.187] => (item=a) => {
"msg": "a"
}
ok: [10.1.61.187] => (item=b) => {
"msg": "b"
}
PLAY RECAP ******************************************************************************************************************************************************************
10.1.61.187 : ok=2 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
# 使用with_list的示例
- hosts: test
gather_facts: no
tasks:
- name: "with_list"
debug:
msg: "{{ item }}"
with_list:
- [1, 2]
- [a, b]
# 返回结果:
# ansible-playbook with_list_ex.yml
PLAY [test] *****************************************************************************************************************************************************************
TASK [with_list] ***********************************************************************************************************************************************************
ok: [10.1.61.187] => (item=[1, 2]) => {
"msg": [
1,
2
]
}
ok: [10.1.61.187] => (item=['a', 'b']) => {
"msg": [
"a",
"b"
]
}
PLAY RECAP ******************************************************************************************************************************************************************
10.1.61.187 : ok=1 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
3. with_flattened
with_flattened与with_items类似，当处理复杂的多级列表嵌套时，会将所有的列表全部拉平：
- hosts: test
gather_facts: no
tasks:
- name: "with_flattened"
debug:
msg: "{{ item }}"
with_flattened:
- [1, 2,[3,4]]
- [a, b]
返回结果：
# ansible-playbook with_flattened_ex.yml
PLAY [test] *****************************************************************************************************************************************************************
TASK [with_flattened] ***********************************************************************************************************************************************************
ok: [10.1.61.187] => (item=1) => {
"msg": 1
}
ok: [10.1.61.187] => (item=2) => {
"msg": 2
}
ok: [10.1.61.187] => (item=3) => {
"msg": 3
}
ok: [10.1.61.187] => (item=4) => {
"msg": 4
}
ok: [10.1.61.187] => (item=a) => {
"msg": "a"
}
ok: [10.1.61.187] => (item=b) => {
"msg": "b"
}
PLAY RECAP ******************************************************************************************************************************************************************
10.1.61.187 : ok=1 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
4. with_together
with_together可以将两个列表中的元素对齐合并
示例如下：
- hosts: test
remote_user: root
vars:
alpha: [ 'a','b']
numbers: [ 1,2]
tasks:
- debug: msg="{{ item.0 }} and {{ item.1 }}"
with_together:
- "{{ alpha }}"
- "{{ numbers }}"
# 输出的结果为：
ok: [10.1.61.187] => (item=['a', 1]) => {
"item": [
"a",
1
],
"msg": "a and 1"
}
ok: [10.1.61.187] => (item=['b', 2]) => {
"item": [
"b",
2
],
"msg": "b and 2"
}
可以看到第一个列表中的第一个元素a与第二个列表中的第一个元素1合并输出，第一个列表中的b与第二个列表中的第二个元素2合并输出了
上面的示例是基于两个列表的元素完全相同的结果，如果两个列表中的元素不同：
- hosts: test
remote_user: root
vars:
alpha: [ 'a','b','c']
numbers: [ 1,2]
tasks:
- debug: msg="{{ item.0 }} and {{ item.1 }}"
with_together:
- "{{ alpha }}"
- "{{ numbers }}"
# 输出结果：
# ansible-playbook with_together_ex.yml
PLAY [test] *****************************************************************************************************************************************************************
TASK [debug] ****************************************************************************************************************************************************************
ok: [10.1.61.187] => (item=['a', 1]) => {
"msg": "a and 1"
}
ok: [10.1.61.187] => (item=['b', 2]) => {
"msg": "b and 2"
}
ok: [10.1.61.187] => (item=['c', None]) => {
"msg": "c and "
}
PLAY RECAP ******************************************************************************************************************************************************************
10.1.61.187 : ok=1 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
5. with_nested
嵌套循环
tasks:
- name: debug loops
debug: msg="name is {{ item[0] }} vaule is {{ item[1] }} "
with_nested:
- ['alice','bob']
- ['a','b','c']
item[0]是循环的第一个列表的值[‘alice’,’bob’]。item[1]是第二个列表的值；以上的执行输出如下：
# ansible-playbook with_nested_ex.yml
PLAY [with_nested test] ********************************************************************************************************************
TASK [debug loops] *************************************************************************************************************************
ok: [10.1.61.187] => (item=['alice', 'a']) => {
"msg": "name is alice vaule is a"
}
ok: [10.1.61.187] => (item=['alice', 'b']) => {
"msg": "name is alice vaule is b"
}
ok: [10.1.61.187] => (item=['alice', 'c']) => {
"msg": "name is alice vaule is c"
}
ok: [10.1.61.187] => (item=['bob', 'a']) => {
"msg": "name is bob vaule is a"
}
ok: [10.1.61.187] => (item=['bob', 'b']) => {
"msg": "name is bob vaule is b"
}
ok: [10.1.61.187] => (item=['bob', 'c']) => {
"msg": "name is bob vaule is c"
}
PLAY RECAP *********************************************************************************************************************************
10.1.61.187 : ok=1 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
下面是一个稍微有用点儿的示例：
- hosts: test
gather_facts: false
tasks:
- file:
state: directory
path: "/data/{{ item[0] }}/{{ item[1] }}"
with_nested:
- [test1,test2]
- [a,b,c]
with_cartesian与其功能完全一致
5. with_indexed_items
在循环处理列表时，为列表中的每一项添加索引（从0开始的数字索引）
简单示例：
- hosts: test
gather_facts: false
tasks:
- debug:
msg: "{{ item }}"
with_indexed_items:
- test1
- test2
- test3
执行之后，返回结果如下：
# ansible-playbook with_indexed_items_ex.yml
PLAY [test] ********************************************************************************************************************************
TASK [debug] *******************************************************************************************************************************
ok: [10.1.61.187] => (item=[0, 'test1']) => {
"msg": [
0,
"test1"
]
}
ok: [10.1.61.187] => (item=[1, 'test2']) => {
"msg": [
1,
"test2"
]
}
ok: [10.1.61.187] => (item=[2, 'test3']) => {
"msg": [
2,
"test3"
]
}
PLAY RECAP *********************************************************************************************************************************
10.1.61.187 : ok=1 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
所以我们可以使用with_indexed_items执行如下操作：
- hosts: test
gather_facts: false
tasks:
- debug:
msg: "index is {{ item[0] }}, value is {{ item[1] }}"
with_indexed_items:
- test1
- test2
- test3
下面再看一个稍微复杂的列表结构：
- hosts: test
gather_facts: false
tasks:
- debug:
msg: "index is {{ item[0] }}, value is {{ item[1] }}"
with_indexed_items:
- test1
- [test2,test3]
- [test4,test5]
这个时候，返回的结果如下：
# ansible-playbook with_indexed_items_ex2.yml
PLAY [test] ********************************************************************************************************************************
TASK [debug] *******************************************************************************************************************************
ok: [10.1.61.187] => (item=[0, 'test1']) => {
"msg": "index is 0, value is test1"
}
ok: [10.1.61.187] => (item=[1, 'test2']) => {
"msg": "index is 1, value is test2"
}
ok: [10.1.61.187] => (item=[2, 'test3']) => {
"msg": "index is 2, value is test3"
}
ok: [10.1.61.187] => (item=[3, 'test4']) => {
"msg": "index is 3, value is test4"
}
ok: [10.1.61.187] => (item=[4, 'test5']) => {
"msg": "index is 4, value is test5"
}
PLAY RECAP *********************************************************************************************************************************
10.1.61.187 : ok=1 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
可以看到，其在处理更复杂列表的时候，会将列表拉平，类似于with_items。
与with_items一样，其也只会拉平第一层列表，如果存在多层列表嵌套，则更深的嵌套不会被拉平：
- hosts: test
gather_facts: false
tasks:
- debug:
msg: "index is {{ item[0] }}, value is {{ item[1] }}"
with_indexed_items:
- test1
- [test2,[test3,test4]]
此时的返回结果：
# ansible-playbook with_indexed_items_ex3.yml
PLAY [test] ********************************************************************************************************************************
TASK [debug] *******************************************************************************************************************************
ok: [10.1.61.187] => (item=[0, 'test1']) => {
"msg": "index is 0, value is test1"
}
ok: [10.1.61.187] => (item=[1, 'test2']) => {
"msg": "index is 1, value is test2"
}
ok: [10.1.61.187] => (item=[2, ['test3', 'test4']]) => {
"msg": "index is 2, value is ['test3', 'test4']"
}
PLAY RECAP *********************************************************************************************************************************
10.1.61.187 : ok=1 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
6. with_sequence
用于返回一个数字序列
参数说明：
start：指定起始值
end：指定结束值
stride：指定步长，即从start至end，每次增加的值
count：生成连续的数字序列，从1开始，到count的值结束
format：格式化输出，类似于linux命令行中的printf格式化输出
关于format参数，更多的格式化输出参数可参考：http://www.zsythink.net/archives/1411
- hosts: test
gather_facts: false
tasks:
# create groups
- group:
name: {{ item }}
state: present
with_items:
- evens
- odds
# create some test users
# [testuser00,testuser01,testuser02,...,testuser32]
- user:
name: {{ item }}
state: present
groups: evens
with_sequence:
start: 0
end: 32
stride: 4
format: testuser%02d
# create a series of directories with even numbers for some reason
# [4,6,8,10,...,16]
- file:
dest: /var/stuff/{{ item }}
state: directory
with_sequence:
start: 4
end: 16
stride: 2
# a simpler way to use the sequence plugin
# create 4 groups
- group:
name: group{{ item }}
state: present
with_sequence: count=4
7. with_random_choice
用于从一个列表的多个值中随机返回一个值
下面的示例，一个列表当中有四个值，连续执行playbook，每次都随机返回一个：
- hosts: test
gather_facts: false
tasks:
- debug: msg={{ item }}
with_random_choice:
- "go through the door"
- "drink from the goblet"
- "press the red button"
- "do nothing"
8. with_dict
循环字典
- hosts: test
gather_facts: no
vars:
# 假如有如下变量内容：
users:
alice:
name: Alice Appleworth
telephone: 123-456-7890
bob:
name: Bob Bananarama
telephone: 987-654-3210
# 现在需要输出每个用户的用户名和手机号：
tasks:
- name: Print phone records
debug:
msg: "User {{ item.key }} is {{ item.value.name }} ({{ item.value.telephone }})"
with_dict: "{{ users }}"
输出如下：
# ansible-playbook with_dict_ex.yml
PLAY [test] ******************************************************************************************************************************************************************************************************
TASK [Print phone records] ***************************************************************************************************************************************************************************************
ok: [10.1.61.187] => (item={'key': 'alice', 'value': {'name': 'Alice Appleworth', 'telephone': '123-456-7890'}}) => {
"msg": "User alice is Alice Appleworth (123-456-7890)"
}
ok: [10.1.61.187] => (item={'key': 'bob', 'value': {'name': 'Bob Bananarama', 'telephone': '987-654-3210'}}) => {
"msg": "User bob is Bob Bananarama (987-654-3210)"
}
PLAY RECAP *******************************************************************************************************************************************************************************************************
10.1.61.187 : ok=1 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
9. with_subelement
with_subelement简单来讲，就是在一个复杂的列表当中，可以对这个列表变量的子元素进行遍历
下面是一个简单的示例：
- hosts: test
gather_facts: no
vars:
users:
- name: bob
hobby:
- Games
- Sports
- name: alice
hobby:
- Music
tasks:
- debug:
msg: "{{ item }}"
with_subelement:
- "{{ users }}"
- hobby
输出结果如下：
# ansible-playbook with_subelement_ex.yml
PLAY [test] *****************************************************************************************************************************************************************
TASK [debug] ****************************************************************************************************************************************************************
ok: [10.1.61.187] => (item=[{'name': 'bob'}, 'Games']) => {
"msg": [
{
"name": "bob"
},
"Games"
]
}
ok: [10.1.61.187] => (item=[{'name': 'bob'}, 'Sports']) => {
"msg": [
{
"name": "bob"
},
"Sports"
]
}
ok: [10.1.61.187] => (item=[{'name': 'alice'}, 'Music']) => {
"msg": [
{
"name": "alice"
},
"Music"
]
}
PLAY RECAP ******************************************************************************************************************************************************************
10.1.61.187 : ok=1 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
可以看到，其按照我们指定的变量users的子项hobby进行了组合输出。with_elementes将hobby子元素的每一项作为一个整体，将其他子元素作为整体，然后组合在一起。
假如现在需要遍历一个用户列表，并创建每个用户，而且还需要为每个用户推送特定的SSH公钥以用于实现远程登录。同时为某一个用户创建独立的mysql登录帐号并为其授权。
示例如下：
- hosts: test
gather_facts: false
vars:
users:
- name: alice
authorized:
- files/keys/master1.id_rsa.pub
- files/keys/master2.id_rsa.pub
mysql:
password: mysql-password
hosts:
- "%"
- "127.0.0.1"
- "::1"
- "localhost"
privs:
- "*.*:SELECT"
- "DB1.*:ALL"
- name: bob
authorized:
- files/keys/master3.id_rsa.pub
mysql:
password: other-mysql-password
hosts:
- "db1"
privs:
- "*.*:SELECT"
- "DB2.*:ALL"
tasks:
- user:
name: "{{ item.name }}"
state: present
generate_ssh_key: yes
with_items: "{{ users }}"
- authorized_key:
user: "{{ item.0.name }}"
key: "{{ lookup('file', item.1) }}"
with_subelements:
- "{{ users }}"
- authorized
- name: Setup MySQL users
mysql_user:
name: "{{ item.0.name }}"
password: "{{ item.0.mysql.password }}""
host: "{{ item.1 }} priv={{ item.0.mysql.privs | join('/') }}"
with_subelements:
- "{{ users }"
- mysql.hosts
```
## 10. with\_file
用于循环主控端的文件列表，获取文件中的内容
> 注意： 循环的是主控端的文件列表，不是被控端的
```bash
- hosts: test
gather_facts: false
tasks:
- debug:
msg: {{ item }}
with_file:
- /etc/ansible/test1.yml
- /etc/ansible/test2.yml
输出如下：
# ansible-playbook with_file_ex.yml
PLAY [test] ********************************************************************************************************************************
TASK [debug] *******************************************************************************************************************************
ok: [10.1.61.187] => (item=content: test1.yaml) => {
"msg": "content: test1.yaml"
}
ok: [10.1.61.187] => (item=content: test2.yml) => {
"msg": "content: test2.yml"
}
PLAY RECAP *********************************************************************************************************************************
10.1.61.187 : ok=1 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
11. with_fileglob
上面with_file用于获取文件的内容，而with_fileglob则用于匹配文件名称。可以通过该关键字，在指定的目录中匹配符合模式的文件名。与with_file相同的是，****操作的文件也是主控端的文件而非被控端的文件
- hosts: test
tasks:
- name: Make key directory
file:
path: /root/.sshkeys
state: directory
mode: 0700
owner: root
group: root
- name: Upload public keys
copy:
src: "{{ item }}"
dest: /root/.sshkeys
mode: 0600
owner: root
group: root
with_fileglob:
- /root/.ssh/*.pub
- name: Assemble keys into authorized_keys file
assemble:
src: /root/.sshkeys
dest: /root/.ssh/authorized_keys
mode: 0600
owner: root
group: root
12. with_lines
with_lines循环结构会让你在控制主机上执行任意命令，并对命令的输出进行逐行迭代。
假设我们有一个文件test.txt包含如下行：
Breeze Yan
Bernie Yang
jerry Qing
我们可以通过如下方法进行逐行输出：
- name: print all names
debug: msg="{{ item }}"
with_lines:
- cat test.txt
13. do-Until循环
- action: shell /usr/bin/foo
register: result
until: result.stdout.find("all systems go") != -1
retries: 5
delay: 10
重复执行shell模块，当shell模块执行的命令输出内容包含”all systems go”的时候停止。重试5次，延迟时间10秒。retries默认值为3，delay默认值为5。任务的返回值为最后一次循环的返回结果。
