ansible filter (编写你自己的ansible filter)

有时候我们写自己的playbook的时候变量处理真的是特别让人头大，有些变量的操作在python中就很简单，但是放到ansible playbook中就会很麻烦，所以，我们今天来看一下如何编写自己的ansible filter来帮助我们处理一下变量

直接看例子吧：

#!/usr/bin/python
class FilterModule(object):
    def filters(self):
        return {
            'a_filter': self.a_filter,
            'another_filter': self.b_filter
        }

    def a_filter(self, a_variable):
        a_new_variable = a_variable + ' CRAZY NEW FILTER'
        return a_new_variable

#!/usr/bin/python

class FilterModule(object):

def filters(self):

return {

'a_filter': self.a_filter,

'another_filter': self.b_filter

}

def a_filter(self, a_variable):

a_new_variable = a_variable + ' CRAZY NEW FILTER'

return a_new_variable

我们来分析一下代码：

定义了一个filter叫a_filter,当让我们有变量传入的时候，我们在原来变量的基础上加上’CRAZY NEW FILTER’ 生成一个新的字符串然后返回

其实这样我们就完成了一个基本的filter的例子

我们来实际使用一下，这里要说明一下，我们自己写的filter要放入和你的playbook同级的filter_plugins/下

例如：

/home/user/my_playbook.yml

/home/user/filter_plugins/my_filters.py

这里python文件名大家随意，核心内容在内容里边

我们创建一个测试用的playbook

---
- hosts: localhost
  tasks:
    - name: Print a message
      debug:
        msg: "{{'test'|a_filter}}"

---

- hosts: localhost

tasks:

- name: Print a message

debug:

msg: "{{'test'|a_filter}}"

我们看一下运行结果

 ansible-playbook my_playbook.yml

PLAY ***************************************************************************

TASK [setup] *******************************************************************
ok: [localhost]

TASK [Print a message] *********************************************************
ok: [localhost] => {
    "msg": "test CRAZY NEW FILTER"
}

PLAY RECAP *********************************************************************
localhost                  : ok=2    changed=0    unreachable=0    failed=0

user@ansibletest:~$

ansible-playbook my_playbook.yml

PLAY ***************************************************************************

TASK [setup] *******************************************************************

ok: [localhost]

TASK [Print a message] *********************************************************

ok: [localhost] => {

"msg": "test CRAZY NEW FILTER"

}

PLAY RECAP *********************************************************************

localhost : ok=2 changed=0 unreachable=0 failed=0

user@ansibletest:~$

我们发现我们的变量’test’在调用了我们的filter: a_filter以后，变量变成了：test CRAZY NEW FILTER

我们来增加另外一个简单的filter b_filter在原来的python文件中

#!/usr/bin/python
class FilterModule(object):
    def filters(self):
        return {
            'a_filter': self.a_filter,
            'another_filter': self.b_filter
        }

    def a_filter(self, a_variable):
        a_new_variable = a_variable + ' CRAZY NEW FILTER'
        return a_new_variable

    def b_filter(self, a_variable, another_variable, yet_another_variable):
        a_new_variable = a_variable + ' - ' + another_variable + ' - ' + yet_another_variable
        return a_new_variable

#!/usr/bin/python

class FilterModule(object):

def filters(self):

return {

'a_filter': self.a_filter,

'another_filter': self.b_filter

}

def a_filter(self, a_variable):

a_new_variable = a_variable + ' CRAZY NEW FILTER'

return a_new_variable

def b_filter(self, a_variable, another_variable, yet_another_variable):

a_new_variable = a_variable + ' - ' + another_variable + ' - ' + yet_another_variable

return a_new_variable

注意，我们调用filter的时候需要使用：another_filter这个是在return函数中的定义，相当于大名和小名

注意：我们的a_variable就是我们调用filter的变量本身，所以我们只需要传递后两个参数即可

再次测试

---
- hosts: localhost
  tasks:
    - name: Print a message
      debug:
        msg: "{{'test'|another_filter('the','filters')}}"

---

- hosts: localhost

tasks:

- name: Print a message

debug:

msg: "{{'test'|another_filter('the','filters')}}"

结果：

ansible-playbook test.yml
[WARNING]: No inventory was parsed, only implicit localhost is available

[WARNING]: provided hosts list is empty, only localhost is available. Note that the implicit localhost does not match 'all'


PLAY [localhost] **************************************************************************************************************************************

TASK [Gathering Facts] ********************************************************************************************************************************
ok: [localhost]

TASK [Print a message] ********************************************************************************************************************************
ok: [localhost] => {
    "msg": "test - the - filters"
}

PLAY RECAP ********************************************************************************************************************************************
localhost                  : ok=2    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

ansible-playbook test.yml

[WARNING]: No inventory was parsed, only implicit localhost is available

[WARNING]: provided hosts list is empty, only localhost is available. Note that the implicit localhost does not match 'all'

PLAY [localhost] **************************************************************************************************************************************

TASK [Gathering Facts] ********************************************************************************************************************************

ok: [localhost]

TASK [Print a message] ********************************************************************************************************************************

ok: [localhost] => {

"msg": "test - the - filters"

}

PLAY RECAP ********************************************************************************************************************************************