Playbook中变量的使用

变量定义

变量名

仅字母、数字和下划线组成，且只能以字母开头

playbook中变量的表示以及赋值

使用{{}} mustache语法，运行playbook时添加-e 参数为变量赋值。

  1. setup模块

内置的setup模块，用于查询内置变量。

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- name: Gathers facts about remote hosts
  setup:
      fact_path:             # Path used for local ansible facts (`*.fact') - files in this dir will be run (if executable) and their results be added to  `ansible_local' facts if a file is not executable it is read. Check notes for Windows options. (from 2.1 on) File/results format can be JSON or INI-format. The default `fact_path' can be  specified in `ansible.cfg' for when setup is automatically called as part of `gather_facts'.
      filter:               # 过滤内容，支持通配符  # If supplied, only return facts that match this shell-style (fnmatch) wildcard.
      gather_subset:         # If supplied, restrict the additional facts collected to the given subset. Possible values: `all', `min', `hardware',  `network', `virtual', `ohai', and `facter'. Can specify a list of values to specify a larger subset. Values can also be used with an initial `!' to specify that that specific subset should not be collected.  For instance: `!hardware,!network,!virtual,!ohai,!facter'. If `!all' is specified then only the min subset is collected. To avoid collecting even the min subset,  specify `!all,!min'. To collect only specific facts, use `!all,!min', and specify the particular fact subsets. Use the filter parameter if you do not want to display some collected  facts.
     gather_timeout:        # Set the default timeout in seconds for individual fact gathering.

#cmdline
ansible host -m setup -a 'filter=<..>'
  1. 在playbook中定义变量
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- hosts:
  remote_user:
  vars:
    - var1: #变量值1
    - var2: #变量值2
  1. 利用命令行指定变量

优先级

命令行的优先级要高于配置文件。

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ansible-playbook -e 'var1=value1 var2=value2' file.yaml
  1. 在/etc/ansible/hosts中定义

主机清单中定义变量

分为普通变量和公共（组）变量，普通变量优先级高于公共（组）变量。

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[websrvs]
192.168.1.10 var1=value1 var2=value2  #普通变量
[websrvs:vars] #公共（组）变量
var3=value3
var1=value0 #由于普通变量优先于公共（组）变量，所以此处不会应用于192.168.1.10主机

为了避免混乱，还可以采用文件的形式来定义。

  1. 在外部yaml文件定义变量并在playbook中引用
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echo -e "var1:value1\nvar2:value2" >> /etc/ansible/vars.yaml

在playbook文件中，使用vars_files引用外部文件

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---
- hosts: 
  remote_user:
  vars_files:
    - /path/to/vars.yaml
    
   tasks:
     - name:
        <moduel>:
  1. 在role文件中定义变量

模板templates

使用Jinja2语法

注意

template模块只能在playbook文件中使用。

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---
- hosts: ubuntu
  remote_user: root
  
  tasks:
     - name: install package
       apt: name=nginx
     - name: copy template
       template: src=nginx.conf.j2 dest=/etc/nginx/nginx.conf
     - name: start service
       service: name=nginx state=started enabled=yes

在playbook文件使用条件判断

when语句

在task后添加when子句可用于条件测试

补充

when语句还支持Jinja2表达式语法。 如：when: var=="value"

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---
- hosts: ubuntu
  remote_user: root
  
  tasks:
     - name: install package
       apt: name=nginx
     - name: copy template
       template: src=nginx.conf.j2 dest=/etc/nginx/nginx.conf
       when: var=="value“
     - name: start service
       service: name=nginx state=started enabled=yes