一、ansible迭代(循環)
loop循環語句
在寫 playbook 的時候發現了很多 task 都要重復引用某個相同的模塊，比如一次啟動10個服務，或者一次拷貝10個文件，如果按照傳統的寫法最少要寫10次，這樣會使得 playbook很臃腫。Ansible提供了兩個用於創建循環的關鍵字：loop和with_ (除了with_items，還有其他可用於循環的比如with_dict)
目前我們習慣於用loop替代with_*
格式：
- 對迭代項的引用，固定變量名為
"item"； - 要在
task中使用with_items或loop關鍵字給定要迭代的元素列表；
實操：
1、使用循環批量安裝軟件
方式1
cat loop.yml
- hosts: web
remote_user: root
tasks:
- name: Install Packages
yum:
name: "{{ item }}"
state: present
loop:
- rsync
- glances
有執行結果可知，glances安裝成功，rsync沒有改變是因為軟件已經安裝有了。
方式2：
cat loop1.yml
- hosts: web
remote_user: root
vars:
packages:
- httpd
- glances
tasks:
- name: Install Packages
yum:
name: "{{ packages }}"
state: present
方式采用變量方方式，顯示上不如loop直觀
方式3：loop調用vars的變量
---
- hosts: web
vars:
test_name:
- test1
- test2
- test3
tasks:
- name: delete user
user:
name: "{{ item }}"
state: present
loop: "{{ test_name }}"
2、使用循環批量啟動服務
cat loop_service.yml
- hosts: NginxWebs
remote_user: root
tasks:
- name: Start Service
service:
name: "{{ item }}"
state: started
loop:
- httpd
- mariadb-server
3、使用循環批量創建用戶
注：此處將loop換成with_items也是一樣
- hosts: web
tasks:
- name: Create Groups
group:
name: "{{ item }}"
state: present
loop:
- group1
- group2
- group3
- name: Create Users
user:
name: "{{ item.user }}"
group: "{{ item.group }}"
uid: "{{ item.uid }}"
state: present
create_home: yes
loop:
- { user: user1,group: group1, uid: 2001 }
- { user: user2,group: group2, uid: 2002 }
- { user: user3,group: group3, uid: 2003 }
4、使用循環批量拷貝文件
- hosts: web
tasks:
- name: Copy Configuer File
template:
src: "{{ item.src }}"
dest: "{{ item.dest }}"
owner: "{{ item.owner }}"
group: "{{ item.group }}"
mode: "{{ item.mode }}"
loop:
- { src: "/root/conf/nginx.conf.j2", dest: "/etc/nginx/nginx.conf", owner: "root", group: "root", mode: "0644" }
- { src: "/root/conf/example.com.conf.j2", dest: "/etc/nginx/conf.d/example.con.conf", owner: "root", group: "root", mode: "0644" }
- { src: "/root/file/index.html", dest: "/data/nginx/example/index.html", owner: "nginx", group: "nginx", mode: 0644 }
注意：應用template時用法和copy一致，但是此處dest目標路徑需要自己提前創建好、屬主（組）都要有
copy是這樣介紹的：
= dest
Remote absolute path where the file should be copied to.
If `src' is a directory, this must be a directory too. #如果 `src' 是一個目錄，dest也必須是一個目錄。
If `dest' is a non-existent path and if either `dest' ends with "/" or `src' is a directory, `dest' is created. #如果 `dest' 是不存在的路徑，並且如果 `dest' 以“/”結尾或 `src' 是目錄，則創建 `dest'。
If `dest' is a relative path, the starting directory is determined by the remote host. #如果“dest”是相對路徑，則起始目錄由遠程主機確定。
If `src' and `dest' are files, the parent directory of `dest' is not created and the task fails if it does not already exist. #如果 `src' 和 `dest' 是文件，則不創建 `dest' 的父目錄，如果不存在則任務失敗。
type: path
5、嵌套循環with_nested、with_cartesian
cat loop6.yml
---
- hosts: web
remote_user: root
gather_facts: no
tasks:
- file:
state: directory
path: "/testdir/{{item.0}}/{{item.1}}"
with_nested:
- [ a, b, c ]
- [ test1, test2 ]
效果
tree /testdir/
/testdir/
|-- a
| |-- test1
| `-- test2
|-- b
| |-- test1
| `-- test2
`-- c
|-- test1
`-- test2
9 directories, 0 files
分別給用戶授予3個數據庫的所有權限
- name: give users access to multiple databases
mysql_user: name={{ item[0] }} priv={{ item[1] }}.*:ALL append_privs=yes password=foo
with_nested:
- [ 'alice', 'bob' ]
- [ 'clientdb', 'employeedb', 'providerdb' ]
6、對哈希表循環（key：value）
---
- hosts: web
vars:
users:
alice:
name: Alice Appleworth
telephone: 123-456-7890
bob:
name: Bob Bananarama
telephone: 987-654-3210
tasks:
- name: Print phone records
debug:
msg: "User {{ item.key }} is {{ item.value.name }} {{ item.value.telephone }}"
with_dict: "{{users}}"
7、對文件列表使用循環
cat loop7.yml
---
- hosts: web
tasks:
- copy:
src: "{{ item }}"
dest: /etc/fooapp/
owner: root
mode: 600
with_fileglob:
- /playbooks/files/fooapp/*
效果
8、對列表循環
如果列表數目不匹配，用None補全
---
- hosts: web
tasks:
- debug:
msg: "{{ item.0 }} and {{ item.1 }}"
with_together:
- [ 'a', 'b', 'c' ]
- [ 1, 2 ]
9、遍歷列表和索引：with_indexed_items
---
- hosts: web
tasks:
- name: indexed loop demo
debug: "msg='at array position {{ item.0 }} there is a value {{ item.1 }}'"
with_indexed_items: [1,2,3]
10、重試循環
---
- hosts: web
tasks:
- action: shell /usr/bin/foo
register: result
until: result.stdout.find("all systems go") != -1
retries: 5
delay: 10
"重試次數retries" 的默認值為3，"delay"為5
二、循環與when
如果將when與循環一起使用時，ansible會為每個循環項都執行單獨的條件判斷，不滿足條件的項就會跳過。
1、打印大於5的數字
cat loop8.yml
---
- hosts: web
debugger: on_failed
tasks:
- name: print items greater than 5
debug:
msg: var is {{ item }}
loop: [0,1,3,5,6,7,8,10]
when: item > 7
效果：大於7的數字被執行
2、指定默認值default，當該集合未定義時，可以按條件跳過
---
- hosts: web
debugger: on_failed
tasks:
- name: print items greater than 5
debug:
msg: "mylist is {{item}}"
loop: "{{ mylist|default([4,5,6]) }}"
when: item > 5
3、與字典循環
---
- hosts: web
debugger: on_failed
vars:
mydict: {"zhangsan":18,"lisi":19,"wangwu":20}
tasks:
- name: print items greater than 5
debug:
msg: "item is {{item.key}}"
loop: "{{ query('dict', mydict|default({})) }}"
when: item.value > 19
效果大於19歲的只有wangwu
三、注冊變量與loop
---
- hosts: web
gather_facts: no
tasks:
- name: delete user
shell: echo '{{ item }}'
loop:
- test1
- test2
register: result
- name: print
debug:
msg: "{{ result.results }}"
Ansible 小手冊系列 十四（條件判斷和循環） - 簡書 (jianshu.com)