Ansible 循环
一、简单介绍
在ansible2.5之前，大多数人使”with_XXX”类型的关键字来操作循环，但是从2.6版本开始，官方推荐是”loop”关键字代替” with_XXX”。
1.我们先看下一个小例子，使用loop关键字进行最简单的循环：
[root@localhost cycle]# cat cycle.1.yml
---
-name: cycletest
hosts: test
gather_facts: no
tasks:
-name: debug cycle
debug:
msg: "{{ item }}"
loop:
- test1
- test2
结果：
[root@localhost cycle]# ansible-playbookcycle.1.yml
PLAY [cycle test]***************************************************************************************
TASK [debug cycle]**************************************************************************************
ok: [192.168.15.10] => (item=test1)=> {
"msg": "test1"
}
ok: [192.168.15.10] => (item=test2)=> {
"msg": "test2"
}
PLAY RECAP**********************************************************************************************
192.168.15.10 : ok=1 changed=0 unreachable=0 failed=0 skipped=0
debug cycle------------------------------------------------------------- 0.17s
Playbook finished: Mon Dec 24 17:57:252018, 1 total tasks. 0:00:00 elapsed.
实例中所以loop关键字，替换之前的with_XXX关键字，它们的效果是完全相同的。
2.我们可以使用loop关键字和dict插件代替”with_dict”关键字，示例如下：
[root@localhost cycle]# cat cycle.2.yml
---
-name: cycle test2
hosts: test
gather_facts: no
vars:
dicts:
China: 1
America: 2
tasks:
-name: debug cycle
debug:
msg: "{{ item.key }} is no.{{ item.value }}"
loop: "{{ lookup('dict',dicts) }}"
结果：
[root@localhost cycle]# ansible-playbookcycle.2.yml
PLAY [cycle test2]**************************************************************************************
TASK [debug cycle] **************************************************************************************
ok: [192.168.15.10] => (item={'key':u'America', 'value': 2}) => {
"msg": "America is no.2"
}
ok: [192.168.15.10] => (item={'key':u'China', 'value': 1}) => {
"msg": "China is no.1"
}
PLAY RECAP**********************************************************************************************
192.168.15.10 : ok=1 changed=0 unreachable=0 failed=0 skipped=0
debug cycle -------------------------------------------------------------0.18s
Playbook finished: Mon Dec 24 17:59:582018, 1 total tasks. 0:00:00 elapsed
示例已经在上一个例子中讲述，再次不在讲述
3.上个例子中使用”loop+lookup”的方式完成循环，而在2.6版本的官网中推荐使用”loop+filter”方式老代替”loop+loopup”的方式，什么意思呢? 我们来看个小例子，如下:
---
-name: cycle test3
hosts: test
gather_facts: no
vars:
dicts:
China: 1
America: 2
tasks:
-name: debug cycle
debug:
msg: "{{ item.key }} is no.{{ item.value }}"
loop: "{{ dicts | dict2items }}"
结果：
[root@localhost cycle]# ansible-playbookcycle.3.yml
PLAY [cycle test3]**************************************************************************************
TASK [debug cycle]**************************************************************************************
ok: [192.168.15.10] => (item={'key':u'America', 'value': 2}) => {
"msg": "America is no.2"
}
ok: [192.168.15.10] => (item={'key':u'China', 'value': 1}) => {
"msg": "China is no.1"
}
PLAY RECAP **********************************************************************************************
192.168.15.10 : ok=1 changed=0 unreachable=0 failed=0 skipped=0
debug cycle------------------------------------------------------------- 0.18s
Playbook finished: Mon Dec 24 18:05:212018, 1 total tasks. 0:00:00 elapsed.
如上例所示，在使用loop关键字操作对于的字典变量users时，并没有借助dict插件，而是使用dict2items的过滤器。
二、具体示例
1.With_list
#loop可以替代with_list，当处理嵌套的列表时，列表不会被拉平
[root@localhost cycle]# cat cycle.4.yml
---
-name: cycle test4
hosts: test
gather_facts: no
vars:
dicts:
- A
- B
- [c,D]
tasks:
-name: debug cycle
debug:
msg: "{{ item }}"
loop: "{{ dicts }}"
结果：
[root@localhost cycle]# ansible-playbookcycle.4.yml
PLAY [cycle test4]**************************************************************************************
TASK [debug cycle]**************************************************************************************
ok: [192.168.15.10] => (item=A) => {
"msg": "A"
}
ok: [192.168.15.10] => (item=B) => {
"msg": "B"
}
ok: [192.168.15.10] => (item=[u'c',u'D']) => {
"msg": [
"c",
"D"
]
}
PLAY RECAP **********************************************************************************************
192.168.15.10 : ok=1 changed=0 unreachable=0 failed=0 skipped=0
debug cycle------------------------------------------------------------- 0.19s
Playbook finished: Mon Dec 24 18:25:412018, 1 total tasks. 0:00:00 elapsed.
2.With_flattened
#flatten过滤器可以替代with_flattened，当处理多层嵌套的列表时，列表中所有的嵌套层级都会被拉平
[root@localhost cycle]# cat cycle.5.yml
---
-name: cycle test5
hosts: test
gather_facts: no
vars:
dicts:
- A
- B
- [c,D]
tasks:
-name: debug cycle
debug:
msg: "{{ item }}"
loop: "{{ dicts | flatten }}"
结果：
[root@localhost cycle]# ansible-playbookcycle.5.yml
PLAY [cycle test5]**************************************************************************************
TASK [debug cycle]**************************************************************************************
ok: [192.168.15.10] => (item=A) => {
"msg": "A"
}
ok: [192.168.15.10] => (item=B) => {
"msg": "B"
}
ok: [192.168.15.10] => (item=c) => {
"msg": "c"
}
ok: [192.168.15.10] => (item=D) => {
"msg": "D"
}
PLAY RECAP**********************************************************************************************
192.168.15.10 : ok=1 changed=0 unreachable=0 failed=0 skipped=0
debug cycle------------------------------------------------------------- 0.19s
Playbook finished: Mon Dec 24 18:31:472018, 1 total tasks. 0:00:00 elapsed.
3.With_items
#flatten过滤器（加参数）可以替代with_items，当处理多层嵌套的列表时，只有列表中的第一层会被拉平
[root@localhost cycle]# cat cycle.6.yml
---
-name: cycle test6
hosts: test
gather_facts: no
vars:
dicts:
- A
- B
- [c,D]
tasks:
-name: debug cycle
debug:
msg: "{{ item }}"
loop: "{{ dicts | flatten(levels=1) }}"
结果：
[root@localhost cycle]# ansible-playbookcycle.6.yml
PLAY [cycle test6] **************************************************************************************
TASK [debug cycle]**************************************************************************************
ok: [192.168.15.10] => (item=A) => {
"msg": "A"
}
ok: [192.168.15.10] => (item=B) => {
"msg": "B"
}
ok: [192.168.15.10] => (item=c) => {
"msg": "c"
}
ok: [192.168.15.10] => (item=D) => {
"msg": "D"
}
PLAY RECAP **********************************************************************************************
192.168.15.10 : ok=1 changed=0 unreachable=0 failed=0 skipped=0
debug cycle------------------------------------------------------------- 0.29s
Playbook finished: Mon Dec 24 18:34:312018, 1 total tasks. 0:00:00 elapsed.
#PS 嗯 处理下客户问题先。Weblogic真毒~
4.With_indexed_items
#flatten过滤器（加参数），再配合loop_control关键字，可以替代with_indexed_items
#当处理多层嵌套的列表时，只有列表中的第一层会被拉平，flatten过滤器的bug暂且忽略
[root@localhost cycle]# cat cycle.7.yml
---
-name: cycle test7
hosts: test
gather_facts: no
vars:
dicts:
- A
- B
- [c,D]
tasks:
-name: debug cycle
debug:
msg: " {{ index}}--{{ item }}"
loop: "{{ dicts | flatten(levels=1) }}"
loop_control:
index_var: index
结果：
[root@localhost cycle]# ansible-playbookcycle.7.yml
PLAY [cycle test7]**************************************************************************************
TASK [debug cycle]**************************************************************************************
ok: [192.168.15.10] => (item=A) => {
"msg": " 0--A"
}
ok: [192.168.15.10] => (item=B) => {
"msg": " 1--B"
}
ok: [192.168.15.10] => (item=c) => {
"msg": " 2--c"
}
ok: [192.168.15.10] => (item=D) => {
"msg": " 3--D"
}
PLAY RECAP**********************************************************************************************
192.168.15.10 : ok=1 changed=0 unreachable=0 failed=0 skipped=0
debug cycle------------------------------------------------------------- 0.21s
Playbook finished: Mon Dec 24 20:29:572018, 1 total tasks. 0:00:00 elapsed.
“loop_control”关键字可以用于控制循环的行为，比如在循环是获取元素的索引。
“index_var “是”loop_control”的一个设置选项，”index_var”可以让我们指定变量,”loop_control”会将元素索引值存放在指定变量中
5.With_togeher
[root@localhost cycle]# cat cycle.8.yml
---
-name: cycle test8
hosts: test
gather_facts: no
vars:
testlist1: [ A,B,C,D ]
testlist2: [ 110,120,911 ]
testlist3: [ x,y ]
tasks:
-name: debug cycle with_together
debug:
msg: " {{ item.0 }} - {{ item.1 }} - {{ item.2 }}"
with_together:
- "{{ testlist1 }}"
- "{{ testlist2 }}"
- "{{ testlist3 }}"
-name: debug cycle loop+zip_logest
debug:
msg: " {{ item.0 }} - {{ item.1 }} - {{ item.2 }}"
loop: "{{ testlist1 | zip_longest(testlist2,testlist3) | list }}
结果：
[root@localhost cycle]# ansible-playbookcycle.8.yml
PLAY [cycle test8]**************************************************************************************
TASK [debug cycle with_together]************************************************************************
ok: [192.168.15.10] => (item=[u'A', 110,u'x']) => {
"msg": " A - 110 - x"
}
ok: [192.168.15.10] => (item=[u'B', 120,u'y']) => {
"msg": " B - 120 - y"
}
ok: [192.168.15.10] => (item=[u'C', 911,None]) => {
"msg": " C - 911 - "
}
ok: [192.168.15.10] => (item=[u'D',None, None]) => {
"msg": " D - -"
}
TASK [debug cycle loop+zip_logest]**********************************************************************
ok: [192.168.15.10] => (item=[u'A', 110,u'x']) => {
"msg": " A - 110 - x"
}
ok: [192.168.15.10] => (item=[u'B', 120,u'y']) => {
"msg": " B - 120 - y"
}
ok: [192.168.15.10] => (item=[u'C', 911,None]) => {
"msg": " C - 911 - "
}
ok: [192.168.15.10] => (item=[u'D',None, None]) => {
"msg": " D - -"
}
PLAY RECAP**********************************************************************************************
192.168.15.10 : ok=2 changed=0 unreachable=0 failed=0 skipped=0
debug cycle with_together----------------------------------------------- 0.25s
debug cycle loop+zip_logest--------------------------------------------- 0.21s
Playbook finished: Mon Dec 24 20:44:422018, 2 total tasks. 0:00:00 elapsed.
示例中同时写出2中方法方便进行比较。
当多个列表使用”with_together”进行对比合并时，如果列表长度不同，这使用最长的列表长度进行对其，由于短列表中元素不足，所以使用空值与长列表中元素进行对齐，zip_longest过滤器也和”with_together”一样，对列表进行组合，但是还需要借助list过滤器，将组合的数据列表化。
可以指定字符代替空值
- debug:
msg: "{{ item.0 }} - {{ item.1 }} - {{item.2}}"
loop: "{{ testlist1 | zip_longest(testlist2,testlist3,fillvalue='None') | list }}"
和最短的列表进行对齐
- debug:
msg: "{{ item.0 }} - {{ item.1 }} - {{item.2}}"
loop: "{{ testlist1 | zip(testlist2,testlist3) | list }}"
6.With_nested/With_cartesian
#product过滤器配合list过滤器，可以替代with_nested和with_cartesian
[root@localhost cycle]# cat cycle.9.yml
---
-name: cycle test4
hosts: test
gather_facts: no
vars:
list1: [ 1,2,3 ]
list2: [ a,b,c,d ]
tasks:
-name: debug cycle
debug:
msg: "{{ item.0 }} ---- {{item.1 }}"
loop: "{{ list1 | product(list2) | list }}"
结果：
[root@localhost cycle]# ansible-playbookcycle.9.yml
PLAY [cycle test4]**************************************************************************************
TASK [debug cycle]**************************************************************************************
ok: [192.168.15.10] => (item=[1, u'a'])=> {
"msg": "1 ---- a"
}
ok: [192.168.15.10] => (item=[1, u'b'])=> {
"msg": "1 ---- b"
}
ok: [192.168.15.10] => (item=[1, u'c'])=> {
"msg": "1 ---- c"
}
ok: [192.168.15.10] => (item=[1, u'd'])=> {
"msg": "1 ---- d"
}
ok: [192.168.15.10] => (item=[2, u'a'])=> {
"msg": "2 ---- a"
}
ok: [192.168.15.10] => (item=[2, u'b'])=> {
"msg": "2 ---- b"
}
ok: [192.168.15.10] => (item=[2, u'c'])=> {
"msg": "2 ---- c"
}
ok: [192.168.15.10] => (item=[2, u'd'])=> {
"msg": "2 ---- d"
}
ok: [192.168.15.10] => (item=[3, u'a'])=> {
"msg": "3 ---- a"
}
ok: [192.168.15.10] => (item=[3, u'b'])=> {
"msg": "3 ---- b"
}
ok: [192.168.15.10] => (item=[3, u'c'])=> {
"msg": "3 ---- c"
}
ok: [192.168.15.10] => (item=[3, u'd'])=> {
"msg": "3 ---- d"
}
PLAY RECAP **********************************************************************************************
192.168.15.10 : ok=1 changed=0 unreachable=0 failed=0 skipped=0
debug cycle------------------------------------------------------------- 0.31s
Playbook finished: Mon Dec 24 20:55:192018, 1 total tasks. 0:00:00 elapsed.
7.With_random_choice
#使用random函数可以替代with_random_choice，由于random函数是随机取出列表中的一个值，并不涉及循环操作，所以并不用使用loop关键字。
[root@localhost cycle]# cat cycle.10.yml
---
-name: cycle test
hosts: test
gather_facts: no
vars:
list: [a,b,c]
tasks:
-name: debug cycle
debug:
msg: "{{ list | random }}"
- debug:
msg: "{{ list | random }}"
- debug:
msg: "{{ list | random }}
结果：
[root@localhost cycle]# ansible-playbookcycle.10.yml
PLAY [cycle test]***************************************************************************************
TASK [debug cycle] **************************************************************************************
ok: [192.168.15.10] => {
"msg": "a"
}
TASK [debug]********************************************************************************************
ok: [192.168.15.10] => {
"msg": "a"
}
TASK [debug]********************************************************************************************
ok: [192.168.15.10] => {
"msg": "c"
}
PLAY RECAP**********************************************************************************************
192.168.15.10 : ok=3 changed=0 unreachable=0 failed=0 skipped=0
debug cycle------------------------------------------------------------- 0.18s
------------------------------------------------------------------------0.16s
Playbook finished: Mon Dec 24 21:06:322018, 2 total tasks. 0:00:00 elapsed.
8.with_dict
#除了上文总结的dict2items过滤器，dictsort过滤器也可以替代with_dict
[root@localhost cycle]# cat cycle.11.yml
---
-name: cycle test2
hosts: test
gather_facts:no
vars:
dicts:
China: 1
America: 2
aaa: 3
bbb: 4
ccc: 5
tasks:
-name: debug cycle dict2items
debug:
msg: "{{ item.key }} is no.{{ item.value }}"
loop: "{{ dicts | dict2items }}"
-name: debug cycle
debug:
msg: "{{ item.0 }} is no.{{ item.1 }}"
loop: "{{ dicts | dictsort }}"
结果：
[root@localhost cycle]# ansible-playbookcycle.11.yml
PLAY [cycle test2]**************************************************************************************
TASK [debug cycle dict2items]***************************************************************************
ok: [192.168.15.10] => (item={'key':u'China', 'value': 1}) => {
"msg": "China is no.1"
}
ok: [192.168.15.10] => (item={'key':u'America', 'value': 2}) => {
"msg": "America is no.2"
}
ok: [192.168.15.10] => (item={'key':u'aaa', 'value': 3}) => {
"msg": "aaa is no.3"
}
ok: [192.168.15.10] => (item={'key':u'bbb', 'value': 4}) => {
"msg": "bbb is no.4"
}
ok: [192.168.15.10] => (item={'key':u'ccc', 'value': 5}) => {
"msg": "ccc is no.5"
}
TASK [debug cycle]**************************************************************************************
ok: [192.168.15.10] => (item=[u'aaa', 3])=> {
"msg": "aaa is no.3"
}
ok: [192.168.15.10] =>(item=[u'America', 2]) => {
"msg": "America is no.2"
}
ok: [192.168.15.10] => (item=[u'bbb',4]) => {
"msg": "bbb is no.4"
}
ok: [192.168.15.10] => (item=[u'ccc',5]) => {
"msg": "ccc is no.5"
}
ok: [192.168.15.10] => (item=[u'China',1]) => {
"msg": "China is no.1"
}
PLAY RECAP **********************************************************************************************
192.168.15.10 : ok=2 changed=0 unreachable=0 failed=0 skipped=0
debug cycle dict2items-------------------------------------------------- 0.26s
debug cycle------------------------------------------------------------- 0.22s
Playbook finished: Mon Dec 24 21:10:402018, 2 total tasks. 0:00:00 elapsed.
