【ansible变量注册多种方式】缥帙各舒散，前后互相逾。这篇文章主要讲述ansible变量注册多种方式相关的知识，希望能为你提供帮助。
使用过ansible的同学都知道，注册变量并使用，是一个很常见的场景。今天就总结下常见的一些情况，了解ansible变量定义、引用及格式化相关内容。
目录
- 1.使用register注册变量
- 1.1 执行一条命令并把返回结果注册为变量
- 1.2 列表遍历的结果注册为变量
- 2.使用set_fact注册变量
- 2.1 使用set_fact注册一个普通变量
- 2.2 使用set_fact给list变量循环添加元素
1.使用register注册变量 当playbook运行的时候，经常需要中途收集一些数据，后面使用它。使用register注册变量是最简单、最常用的一种方式。
1.1 执行一条命令并把返回结果注册为变量 我们最常用的是，执行一条shell命令，并将返回结果注册为一个变量，例如：
tasks:
- name: define a var1
shell: "whoami"
register: whoami- debug:
msg: "whoami: {{ whoami }}"- debug:
msg: "whoami.stdout: {{whoami.stdout}}"
这里要注意，ansible执行结果一般都会返回一个字典类型的数据，你会看到很多你不关心的字段，可以通过指定字典的key，例如stdout或stdout_lines，只看到你关心的数据。请看返回结果：
TASK [define a var1] ************************************************************************************************************************************************************************
changed: [vagrant1]TASK [debug] ********************************************************************************************************************************************************************************
ok: [vagrant1] =>
{
"msg": "whoami: {\'stderr_lines\': [], u\'changed\': True, u\'end\': u\'2020-04-19 15:18:18.278098\', \'failed\': False, u\'stdout\': u\'vagrant\', u\'cmd\': u\'whoami\', u\'rc\': 0, u\'start\': u\'2020-04-19 15:18:18.274052\', u\'stderr\': u\'\', u\'delta\': u\'0:00:00.004046\', \'stdout_lines\': [u\'vagrant\']}"
}TASK [debug] ********************************************************************************************************************************************************************************
ok: [vagrant1] =>
{
"msg": "whoami.stdout: vagrant"
}
1.2 列表遍历的结果注册为变量 这种场景，一般是列表中的元素逐个要参与运算，将运算后的结果存入一个变量，看一个示例：
---- hosts: "{{ hosts_group }}"
remote_user: vagrant
vars:
userss: []tasks:
- name: define users in a loop
shell: "grep {{ item }} /etc/passwd|cat"
register: users
with_items:
- vagrant
- root
- nginx- name: show users
debug:
msg: "{{ users }}"- name: show users.results
debug:
msg: "{{ users.results }}"- name: define userss by set_fact
set_fact:
userss: "{{userss +item.stdout_lines}}"
with_list: "{{ users.results }}"- name: print userss
debug:
msg: "{{ userss }}"- name: print userss one by one
debug:
msg: "{{ item }}"
with_list: "{{ userss}}"- name: print part of userss one by one
debug:
msg: "{{ item.split(\':\')[6] }}"
with_list: "{{ userss}}"
该示例是通过关键字是查询系统的用户及shell信息，ansible会返回一个字典，查询的结果存储在字典名称为results的key对应的value中，这个value本身是一个list。因为我们都不知道到底会查到几个用户，所以再把结果list遍历一遍，存储到另外一个变量中。我们使用set_fact实现了循环给空list变量添加数据的效果。最后，我们分别获取每行的数据，并且进行拆分，获取到了第7个字段。请看返回结果：
TASK [define users in a loop] ***************************************************************************************************************************************************************
changed: [vagrant1] =>
(item=vagrant)
changed: [vagrant1] =>
(item=root)
changed: [vagrant1] =>
(item=nginx)TASK [show users] ***************************************************************************************************************************************************************************
ok: [vagrant1] =>
{
"msg": {
"changed": true,
"msg": "All items completed",
"results": [
{
"_ansible_ignore_errors": null,
"_ansible_item_label": "vagrant",
"_ansible_item_result": true,
"_ansible_no_log": false,
"_ansible_parsed": true,
"changed": true,
"cmd": "grep vagrant /etc/passwd|cat",
"delta": "0:00:00.004695",
"end": "2020-04-19 15:18:19.129083",
"failed": false,
"invocation": {
"module_args": {
"_raw_params": "grep vagrant /etc/passwd|cat",
"_uses_shell": true,
"argv": null,
"chdir": null,
"creates": null,
"executable": null,
"removes": null,
"stdin": null,
"warn": true
}
},
"item": "vagrant",
"rc": 0,
"start": "2020-04-19 15:18:19.124388",
"stderr": "",
"stderr_lines": [],
"stdout": "vagrant:x:1000:1000:vagrant:/home/vagrant:/bin/bash",
"stdout_lines": [
"vagrant:x:1000:1000:vagrant:/home/vagrant:/bin/bash"
]
},
{
"_ansible_ignore_errors": null,
"_ansible_item_label": "root",
"_ansible_item_result": true,
"_ansible_no_log": false,
"_ansible_parsed": true,
"changed": true,
"cmd": "grep root /etc/passwd|cat",
"delta": "0:00:00.004695",
"end": "2020-04-19 15:18:19.421598",
"failed": false,
"invocation": {
"module_args": {
"_raw_params": "grep root /etc/passwd|cat",
"_uses_shell": true,
"argv": null,
"chdir": null,
"creates": null,
"executable": null,
"removes": null,
"stdin": null,
"warn": true
}
},
"item": "root",
"rc": 0,
"start": "2020-04-19 15:18:19.416903",
"stderr": "",
"stderr_lines": [],
"stdout": "root:x:0:0:root:/root:/bin/bash\\noperator:x:11:0:operator:/root:/sbin/nologin",
"stdout_lines": [
"root:x:0:0:root:/root:/bin/bash",
"operator:x:11:0:operator:/root:/sbin/nologin"
]
},
{
"_ansible_ignore_errors": null,
"_ansible_item_label": "nginx",
"_ansible_item_result": true,
"_ansible_no_log": false,
"_ansible_parsed": true,
"changed": true,
"cmd": "grep nginx /etc/passwd|cat",
"delta": "0:00:00.004500",
"end": "2020-04-19 15:18:19.714496",
"failed": false,
"invocation": {
"module_args": {
"_raw_params": "grep nginx /etc/passwd|cat",
"_uses_shell": true,
"argv": null,
"chdir": null,
"creates": null,
"executable": null,
"removes": null,
"stdin": null,
"warn": true
}
},
"item": "nginx",
"rc": 0,
"start": "2020-04-19 15:18:19.709996",
"stderr": "",
"stderr_lines": [],
"stdout": "",
"stdout_lines": []
}
]
}
}TASK [show users.results] *******************************************************************************************************************************************************************
ok: [vagrant1] =>
{
"msg": [
{
"_ansible_ignore_errors": null,
"_ansible_item_label": "vagrant",
"_ansible_item_result": true,
"_ansible_no_log": false,
"_ansible_parsed": true,
"changed": true,
"cmd": "grep vagrant /etc/passwd|cat",
"delta": "0:00:00.004695",
"end": "2020-04-19 15:18:19.129083",
"failed": false,
"invocation": {
"module_args": {
"_raw_params": "grep vagrant /etc/passwd|cat",
"_uses_shell": true,
"argv": null,
"chdir": null,
"creates": null,
"executable": null,
"removes": null,
"stdin": null,
"warn": true
}
},
"item": "vagrant",
"rc": 0,
"start": "2020-04-19 15:18:19.124388",
"stderr": "",
"stderr_lines": [],
"stdout": "vagrant:x:1000:1000:vagrant:/home/vagrant:/bin/bash",
"stdout_lines": [
"vagrant:x:1000:1000:vagrant:/home/vagrant:/bin/bash"
]
},
{
"_ansible_ignore_errors": null,
"_ansible_item_label": "root",
"_ansible_item_result": true,
"_ansible_no_log": false,
"_ansible_parsed": true,
"changed": true,
"cmd": "grep root /etc/passwd|cat",
"delta": "0:00:00.004695",
"end": "2020-04-19 15:18:19.421598",
"failed": false,
"invocation": {
"module_args": {
"_raw_params": "grep root /etc/passwd|cat",
"_uses_shell": true,
"argv": null,
"chdir": null,
"creates": null,
"executable": null,
"removes": null,
"stdin": null,
"warn": true
}
},
"item": "root",
"rc": 0,
"start": "2020-04-19 15:18:19.416903",
"stderr": "",
"stderr_lines": [],
"stdout": "root:x:0:0:root:/root:/bin/bash\\noperator:x:11:0:operator:/root:/sbin/nologin",
"stdout_lines": [
"root:x:0:0:root:/root:/bin/bash",
"operator:x:11:0:operator:/root:/sbin/nologin"
]
},
{
"_ansible_ignore_errors": null,
"_ansible_item_label": "nginx",
"_ansible_item_result": true,
"_ansible_no_log": false,
"_ansible_parsed": true,
"changed": true,
"cmd": "grep nginx /etc/passwd|cat",
"delta": "0:00:00.004500",
"end": "2020-04-19 15:18:19.714496",
"failed": false,
"invocation": {
"module_args": {
"_raw_params": "grep nginx /etc/passwd|cat",
"_uses_shell": true,
"argv": null,
"chdir": null,
"creates": null,
"executable": null,
"removes": null,
"stdin": null,
"warn": true
}
},
"item": "nginx",
"rc": 0,
"start": "2020-04-19 15:18:19.709996",
"stderr": "",
"stderr_lines": [],
"stdout": "",
"stdout_lines": []
}
]
}TASK [define userss by set_fact] ************************************************************************************************************************************************************
ok: [vagrant1] =>
(item={\'_ansible_parsed\': True, \'stderr_lines\': [], \'_ansible_item_result\': True, u\'end\': u\'2020-04-19 15:18:19.129083\', \'_ansible_no_log\': False, u\'stdout\': u\'vagrant:x:1000:1000:vagrant:/home/vagrant:/bin/bash\', u\'cmd\': u\'grep vagrant /etc/passwd|cat\', u\'rc\': 0, \'item\': u\'vagrant\', u\'delta\': u\'0:00:00.004695\', \'_ansible_item_label\': u\'vagrant\', u\'stderr\': u\'\', u\'changed\': True, u\'invocation\': {u\'module_args\': {u\'warn\': True, u\'executable\': None, u\'_uses_shell\': True, u\'_raw_params\': u\'grep vagrant /etc/passwd|cat\', u\'removes\': None, u\'argv\': None, u\'creates\': None, u\'chdir\': None, u\'stdin\': None}}, \'stdout_lines\': [u\'vagrant:x:1000:1000:vagrant:/home/vagrant:/bin/bash\'], u\'start\': u\'2020-04-19 15:18:19.124388\', \'_ansible_ignore_errors\': None, \'failed\': False})
ok: [vagrant1] =>
(item={\'_ansible_parsed\': True, \'stderr_lines\': [], \'_ansible_item_result\': True, u\'end\': u\'2020-04-19 15:18:19.421598\', \'_ansible_no_log\': False, u\'stdout\': u\'root:x:0:0:root:/root:/bin/bash\\noperator:x:11:0:operator:/root:/sbin/nologin\', u\'cmd\': u\'grep root /etc/passwd|cat\', u\'rc\': 0, \'item\': u\'root\', u\'delta\': u\'0:00:00.004695\', \'_ansible_item_label\': u\'root\', u\'stderr\': u\'\', u\'changed\': True, u\'invocation\': {u\'module_args\': {u\'warn\': True, u\'executable\': None, u\'_uses_shell\': True, u\'_raw_params\': u\'grep root /etc/passwd|cat\', u\'removes\': None, u\'argv\': None, u\'creates\': None, u\'chdir\': None, u\'stdin\': None}}, \'stdout_lines\': [u\'root:x:0:0:root:/root:/bin/bash\', u\'operator:x:11:0:operator:/root:/sbin/nologin\'], u\'start\': u\'2020-04-19 15:18:19.416903\', \'_ansible_ignore_errors\': None, \'failed\': False})
ok: [vagrant1] =>
(item={\'_ansible_parsed\': True, \'stderr_lines\': [], \'_ansible_item_result\': True, u\'end\': u\'2020-04-19 15:18:19.714496\', \'_ansible_no_log\': False, u\'stdout\': u\'\', u\'cmd\': u\'grep nginx /etc/passwd|cat\', u\'rc\': 0, \'item\': u\'nginx\', u\'delta\': u\'0:00:00.004500\', \'_ansible_item_label\': u\'nginx\', u\'stderr\': u\'\', u\'changed\': True, u\'invocation\': {u\'module_args\': {u\'warn\': True, u\'executable\': None, u\'_uses_shell\': True, u\'_raw_params\': u\'grep nginx /etc/passwd|cat\', u\'removes\': None, u\'argv\': None, u\'creates\': None, u\'chdir\': None, u\'stdin\': None}}, \'stdout_lines\': [], u\'start\': u\'2020-04-19 15:18:19.709996\', \'_ansible_ignore_errors\': None, \'failed\': False})TASK [print userss] *************************************************************************************************************************************************************************
ok: [vagrant1] =>
{
"msg": [
"vagrant:x:1000:1000:vagrant:/home/vagrant:/bin/bash",
"root:x:0:0:root:/root:/bin/bash",
"operator:x:11:0:operator:/root:/sbin/nologin"
]
}TASK [print userss one by one] **************************************************************************************************************************************************************
ok: [vagrant1] =>
(item=vagrant:x:1000:1000:vagrant:/home/vagrant:/bin/bash) =>
{
"msg": "vagrant:x:1000:1000:vagrant:/home/vagrant:/bin/bash"
}
ok: [vagrant1] =>
(item=root:x:0:0:root:/root:/bin/bash) =>
{
"msg": "root:x:0:0:root:/root:/bin/bash"
}
ok: [vagrant1] =>
(item=operator:x:11:0:operator:/root:/sbin/nologin) =>
{
"msg": "operator:x:11:0:operator:/root:/sbin/nologin"
}TASK [print part of userss one by one] ******************************************************************************************************************************************************
ok: [vagrant1] =>
(item=vagrant:x:1000:1000:vagrant:/home/vagrant:/bin/bash) =>
{
"msg": "/bin/bash"
}
ok: [vagrant1] =>
(item=root:x:0:0:root:/root:/bin/bash) =>
{
"msg": "/bin/bash"
}
ok: [vagrant1] =>
(item=operator:x:11:0:operator:/root:/sbin/nologin) =>
{
"msg": "/sbin/nologin"
}
2.使用set_fact注册变量 其实上个示例，已经提到了set_fact，因为set_fact配合register可以实现一些重要和灵活的功能。
2.1 使用set_fact注册一个普通变量
tasks:
- name: define a var1
shell: "whoami"
register: whoami- debug:
msg: "whoami: {{ whoami }}"- debug:
msg: "whoami.stdout: {{whoami.stdout}}"- name: define a var by set_fact
set_fact:
whoami: "{{ whoami.stdout}}"- name:show a var after defined by set_fact
debug:
msg: "{{ whoami }}"
使用这种方式，会简化变量的调用。2.2 使用set_fact给list变量循环添加元素 这个功能只有通过set_fact可以显示，在好多场景都会用到，尤其是你不知道自己注册的变量有多少个元素，而且配合register可以大大简化变量的后续调用和重新格式化。其实示例1.2的示例代码已经用了这种方式：
vars:
userss: []- name: define userss by set_fact
set_fact:
userss: "{{userss +item.stdout_lines}}"
with_list: "{{ users.results }}"- name: print userss
debug:
msg: "{{ userss }}"- name: print userss one by one
debug:
msg: "{{ item }}"
with_list: "{{ userss}}"- name: print part of userss one by one
debug:
msg: "{{ item.split(\':\')[6] }}"
with_list: "{{ userss}}"
尤其要注意，循环给list变量添加元素的时候，这个变量要已经定义过了，才可以循环添加元素。最后print part的时候，在ansible中调用了python的字符串拆分函数，对遍历到的每行元素进行拆分，获取我们最需要的字段。 先组合字符串，再拆分字符串，会简化整体playbook，避免使用难以理解容易出错的嵌套循环。完整的示例，可以看这里： https://github.com/byygyy/ansible-best-practice/blob/master/test-vars-define.yml
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