ansible会使用ansible facts收集主机信息，针对使用度较高的主机IP提供多种获取方法。
获取IP地址及使用范围可参考这篇文章的写法
https://www.middlewareinventory.com/blog/ansible-get-ip-address/
使用度最广的写法：
{{hostvars[inventory_hostname]['ansible_env'].SSH_CONNECTION.split(' ')[2]}}
规范写法：（需主机设定默认ip）
{{ hostvars[inventory_hostname]['ansible_default_ipv4']['address']}}
简便写法：（需了解默认网卡）
ansible_enp0s8.ipv4.address
官方建议写法best practice：
https://docs.ansible.com/ansible/latest/user_guide/playbooks_variables.html
Some provided facts, like networking information, are made available as nested data structures. To access them a simple {{ foo }} is not sufficient, but it is still easy to do. Here’s how we get an IP address:
{{ ansible_facts["eth0"]["ipv4"]["address"]}}
OR alternatively:
{{ ansible_facts.eth0.ipv4.address }}
Similarly, this is how we access the first element of an array:
{{ foo[0]}}
如：groups['teleport-auth'][0]]
