直接在task中定义：
---
- hosts: all
remote_user: root
tasks:
- apt: name=cobbler state=installed
environment:
http_proxy: http://proxy.example.com:8080
在task中调用变量：
---
- hosts: all
remote_user: root
# here we make a variable named "proxy_env" that is a dictionary
vars:
proxy_env:
http_proxy: http://proxy.example.com:8080
tasks:
- apt: name=cobbler state=installed
environment: "{{proxy_env}}"
在playbook中定义：
---
- hosts: testhost
roles:
- php
- nginx
environment:
http_proxy: http://proxy.example.com:8080
在组变量中定义：
---
# file: group_vars/boston
ntp_server: ntp.bos.example.com
backup: bak.bos.example.com
proxy_env:
http_proxy: http://proxy.bos.example.com:8080
https_proxy: http://proxy.bos.example.com:8080
使用lineinfile模块在被管主机配置文件/etc/environment中定义：
http_proxy="http://proxy.bos.example.com:8080"
https_proxy="http://proxy.bos.example.com:8080"
