Ansible hostvars
https://www.cnblogs.com/v394435982/p/5480758.html
Ansible 的 hostvars/group_names/groups 的使用
https://blog.csdn.net/qianggezhishen/article/details/51821033
Ansible_playbook_内置变量
https://www.jianshu.com/p/44e41bfc56f4
Ansible 中 hostvars, groups, group_names, inventory_hostname 等变量
https://blog.csdn.net/Man_In_The_Night/article/details/88567188
An Ansible summary
https://gist.github.com/andreicristianpetcu/b892338de279af9dac067891579cad7d
Docs » User Guide » Working With Playbooks » Using Variables
https://docs.ansible.com/ansible/latest/user_guide/playbooks_variables.html
