Ansible循环语句
1 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。
2 with_items
[root@node1 ansible]# vim with_items.yml
- hosts: demo2.example.com gather_facts: no tasks: - debug: msg: "{{ item }}" with_items: "{{ groups.webserver }}"
相当于
- hosts: demo2.example.com gather_facts: no tasks: - debug: msg: "{{ item }}" with_items: - demo1.example.com - demo2.example.com - demo3.example.com
[root@node1 ansible]# ansible-playbook with_items.yml
ok: [demo2.example.com] => (item=demo1.example.com) => { "msg": "demo1.example.com" } ok: [demo2.example.com] => (item=demo2.example.com) => { "msg": "demo2.example.com" } ok: [demo2.example.com] => (item=demo3.example.com) => { "msg": "demo3.example.com" }
[root@node1 ansible]# vim with_items.yml
- hosts: demo2.example.com gather_facts: no tasks: - name: "create directory" file: path: "/tmp/{{ item.path1 }}/{{ item.path2 }}" state: directory with_items: - {path1: a, path2: b} - {path1: c, path2: d}
执行
[root@node1 ansible]# ansible demo2.example.com -m shell -a "ls -l /tmp/{a,c}"
/tmp/a: total 0 drwxr-xr-x 2 root root 6 May 2 01:01 b /tmp/c: total 0 drwxr-xr-x 2 root root 6 May 2 01:01 d
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_iems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。with_flatten会将所有列表全部拉平
[[1,2,[3,4]],[5,6],7,8]
with_item------->[1,2,[3,4],5,6,7,8] 拉平第一层
with_list--------->[[1,2,[3,4]],[5,6],7,8] 整体返回
with_flatten----->[1,2,3,4,5,6,7,8] 全部拉平
3 with_togther
将两个列表对齐合并
[root@node1 ansible]# vim with_items.yml
- hosts: demo2.example.com gather_facts: no vars: alpha: [ 'a','b','c','d'] numbers: [ 1,2,3,4 ] tasks: - debug: msg="{{ item.0 }} and {{ item.1 }}" with_together: - "{{ alpha }}" - "{{ numbers }}"
[root@node1 ansible]# ansible-playbook with_items.yml
ok: [demo2.example.com] => (item=[u'a', 1]) => { "msg": "a and 1" } ok: [demo2.example.com] => (item=[u'b', 2]) => { "msg": "b and 2" } ok: [demo2.example.com] => (item=[u'c', 3]) => { "msg": "c and 3" } ok: [demo2.example.com] => (item=[u'd', 4]) => { "msg": "d and 4" }
4 with_nested
嵌套循环，相当于像个for
[root@node1 ansible]# vim with_items.yml
- hosts: demo2.example.com gather_facts: no tasks: - debug: msg="name is {{ item[0] }} vaule is {{ item[1] }} num is {{ item[2] }}" with_nested: - ['alice','bob'] - ['a','b','c'] - ['1','2','3']
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:
[root@node1 ansible]# ansible-playbook with_items.yml
ok: [demo2.example.com] => (item=[u'alice', u'a', u'1']) => { "msg": "name is alice vaule is a num is 1" } ok: [demo2.example.com] => (item=[u'alice', u'a', u'2']) => { "msg": "name is alice vaule is a num is 2" } ok: [demo2.example.com] => (item=[u'alice', u'a', u'3']) => { "msg": "name is alice vaule is a num is 3" } ok: [demo2.example.com] => (item=[u'alice', u'b', u'1']) => { "msg": "name is alice vaule is b num is 1" } ok: [demo2.example.com] => (item=[u'alice', u'b', u'2']) => { "msg": "name is alice vaule is b num is 2" } ok: [demo2.example.com] => (item=[u'alice', u'b', u'3']) => { "msg": "name is alice vaule is b num is 3" } ok: [demo2.example.com] => (item=[u'alice', u'c', u'1']) => { "msg": "name is alice vaule is c num is 1" } ok: [demo2.example.com] => (item=[u'alice', u'c', u'2']) => { "msg": "name is alice vaule is c num is 2" } ok: [demo2.example.com] => (item=[u'alice', u'c', u'3']) => { "msg": "name is alice vaule is c num is 3" } ok: [demo2.example.com] => (item=[u'bob', u'a', u'1']) => { "msg": "name is bob vaule is a num is 1" } ok: [demo2.example.com] => (item=[u'bob', u'a', u'2']) => { "msg": "name is bob vaule is a num is 2" } ok: [demo2.example.com] => (item=[u'bob', u'a', u'3']) => { "msg": "name is bob vaule is a num is 3" } ok: [demo2.example.com] => (item=[u'bob', u'b', u'1']) => { "msg": "name is bob vaule is b num is 1" } ok: [demo2.example.com] => (item=[u'bob', u'b', u'2']) => { "msg": "name is bob vaule is b num is 2" } ok: [demo2.example.com] => (item=[u'bob', u'b', u'3']) => { "msg": "name is bob vaule is b num is 3" } ok: [demo2.example.com] => (item=[u'bob', u'c', u'1']) => { "msg": "name is bob vaule is c num is 1" } ok: [demo2.example.com] => (item=[u'bob', u'c', u'2']) => { "msg": "name is bob vaule is c num is 2" } ok: [demo2.example.com] => (item=[u'bob', u'c', u'3']) => { "msg": "name is bob vaule is c num is 3" }
with_cartesian功能完全一样
5 with_index_items
在循环处理列表时，为列表的每一项添加索引
[root@node1 ansible]# vim with_items.yml
- hosts: demo2.example.com gather_facts: no tasks: - debug: msg: "{{ item }}" with_indexed_items: - test1 - test2 - test3
[root@node1 ansible]# ansible-playbook with_items.yml
ok: [demo2.example.com] => (item=[0, u'test1']) => { "msg": [ 0, "test1" ] } ok: [demo2.example.com] => (item=[1, u'test2']) => { "msg": [ 1, "test2" ] } ok: [demo2.example.com] => (item=[2, u'test3']) => { "msg": [ 2, "test3" ] }
6 with_sequence
用于返回一个数字序列
参数说明
start:指走起始值
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lnuX命令行中的 printi格式化输出
- hosts: all tasks: # create groups - group: name=evens state=present - group: name=odds state=present # create some test users - user: name={{ item }} state=present groups=evens with_sequence: start=0 end=32 format=testuser%02d # create a series of directories with even numbers for some reason - file: dest=/var/stuff/{{ item }} state=directory with_sequence: start=4 end=16 stride=2 # stride用于指定步长 # 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
- debug: msg={{ item }} with_random_choice: - "go through the door" - "drink from the goblet" - "press the red button" - "do nothing"
8 with_dict
[root@node1 ansible]# vi with_items.yml
- hosts: demo2.example.com gather_facts: no vars: 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 }}"
[root@node1 ansible]# ansible-playbook with_items.yml
ok: [demo2.example.com] => (item={'value': {u'name': u'Bob Bananarama', u'telephone': u'987-654-3210'}, 'key': u'bob'}) => {
"msg": "User bob is Bob Bananarama (987-654-3210)"
}
ok: [demo2.example.com] => (item={'value': {u'name': u'Alice Appleworth', u'telephone': u'123-456-7890'}, 'key': u'alice'}) => {
"msg": "User alice is Alice Appleworth (123-456-7890)"
}
9 with_subelement
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配置以特定的SSH key登录。变量文件内容如下：
with_file,是在主控端完成
上面with_file用于获取文的内容，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，with_ fileglob操作的文件也是主控端的文件而非被控端的文件
10 loop关键字说明
在playbook中使用循环，直接使用loop关键字即可。
with_list,with_item可以直接试用loop代替
with_flatten,loop:"{{ testlist| flatten}}"
启动httpd和postfilx服务：
tasks: - name: postfix and httpd are running service: name: "{{ item }}" state: started loop: - postfix - httpd
也可以将loop循环的列表提前赋值给一个变量，然后在循环语句中调用：
#cat test_services.yml test_services: - postfix - httpd # cat install_pkgs.yml - name: start services hosts: test vars_files: - test_services.yml tasks: - name: postfix and httpd are running service: name: "{{ item }}" state: started loop: "{{ test_services }}"
下面是一个循环更复杂类型数据的示例：
# cat test_loop.yml - name: test loop hosts: test tasks: - name: add www group group: name: www - name: add several users user: name: "{{ item.name }}" state: present groups: "{{ item.groups }}" loop: - { name: 'testuser1', groups: 'wheel' } - { name: 'testuser2', groups: 'www' }
11 在循环语句中注册变量
下面是一个register的变量在循环中使用的例子：
# cat register_loop.yml - name: registered variable usage as a loop list hosts: test tasks: - name: ensure /mnt/bkspool exists file: path: /mnt/bkspool state: directory - name: retrieve the list of home directories command: ls /home register: home_dirs - name: Show home_dirs results debug: var: home_dirs.stdout_lines - name: add home dirs to the backup spooler file: path: /mnt/bkspool/{{ item }} src: /home/{{ item }} state: link force: yes loop: "{{ home_dirs.stdout_lines }}"
在循环语句中注册变量：
- name: Loop Register test gather_facts: no hosts: webserver tasks: - name: Looping Echo Task shell: "echo this is my item: {{ item }}" loop: - one - two register: echo_results - name: Show echo_results variable debug: var: echo_results
执行语句，可以看到变量的
"echo_results": { "changed": true, "msg": "All items completed", "results": [ { "ansible_loop_var": "item", "changed": true, "cmd": "echo this is my item: one", "delta": "0:00:00.004610", "end": "2020-05-02 02:16:40.824482", "failed": false, "invocation": { "module_args": { "_raw_params": "echo this is my item: one", "_uses_shell": true, "argv": null, "chdir": null, "creates": null, "executable": null, "removes": null, "stdin": null, "stdin_add_newline": true, "strip_empty_ends": true, "warn": true } }, "item": "one", "rc": 0, "start": "2020-05-02 02:16:40.819872", "stderr": "", "stderr_lines": [], "stdout": "this is my item: one", "stdout_lines": [ "this is my item: one" ] }, { "ansible_loop_var": "item", "changed": true, "cmd": "echo this is my item: two", "delta": "0:00:00.006417", "end": "2020-05-02 02:16:41.372681", "failed": false, "invocation": { "module_args": { "_raw_params": "echo this is my item: two", "_uses_shell": true, "argv": null, "chdir": null, "creates": null, "executable": null, "removes": null, "stdin": null, "stdin_add_newline": true, "strip_empty_ends": true, "warn": true } }, "item": "two", "rc": 0, "start": "2020-05-02 02:16:41.366264", "stderr": "", "stderr_lines": [], "stdout": "this is my item: two", "stdout_lines": [ "this is my item: two" ] } ] } }
返回结果为一个字典列表
博主声明：本文的内容来源主要来自誉天教育晏威老师，由本人实验完成操作验证，需要的博友请联系誉天教育（http://www.yutianedu.com/），获得官方同意或者晏老师（https://www.cnblogs.com/breezey/）本人同意即可转载，谢谢！