我们可以在主机上使用if条件

Question

如何使用条件变量在一组特定主机上运行剧本

vars_file.yml

deployment: blue

hosts_file.yml

[east1]
127.0.0.1
127.0.0.2
[west2]
127.0.0.3
127.0.0.4

playbook.yml

---
hosts: all
vars_files:
- 'vars_file.yml'
tasks:
- copy: src=config dest=/tmp/
hosts: {{ east1[0] if deployment == "blue" else west2[0]}}
vars_files:
- 'vars_file.yml'
tasks:
- shell: "./startup_script restart"

注意:我不能通过命令行传递变量，我不能将任务隔离到一个新的剧本。

Answer 1

您可以通过针对另一台主机的hostvars字典键来访问在该主机上定义的变量。
为了做到这一点，您需要在主机上注册变量，使用set_fact，导入它是不够的。

下面是一个给定库存的例子:

all:
children:
east1:
hosts:
east_node_1:
ansible_host: node1
east_node_2:
ansible_host: node4
west2:
hosts:
west_node_1:
ansible_host: node2
west_node_2:
ansible_host: node3

和剧本:

- hosts: localhost
gather_facts: no
vars_files:
- vars_file.yml
tasks:
- set_fact:
deployment: "{{ deployment }}"
- hosts: >-
{{ groups['east1'][0] 
if hostvars['localhost'].deployment == 'blue' 
else groups['west2'][0] 
}}
gather_facts: no
tasks:
- debug:

这将产生重播:

• PLAY [localhost] *******************************************************************************************************************
  TASK [set_fact] ********************************************************************************************************************
  ok: [localhost]
  PLAY [east_node_1] *****************************************************************************************************************
  TASK [debug] ***********************************************************************************************************************
  ok: [east_node_1] => {
  "msg": "Hello world!"
  }
  PLAY RECAP *************************************************************************************************************************
  east_node_1                : ok=2    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0   
  localhost                  : ok=2    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0   
  

  当vars_file。yml

  deployment: blue
  

• ,

  PLAY [localhost] *******************************************************************************************************************
  TASK [set_fact] ********************************************************************************************************************
  ok: [localhost]
  PLAY [west_node_1] *****************************************************************************************************************
  TASK [debug] ***********************************************************************************************************************
  ok: [west_node_1] => {
  "msg": "Hello world!"
  }
  PLAY RECAP *************************************************************************************************************************
  west_node_1                : ok=2    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0   
  localhost                  : ok=2    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0   
  

  当vars_file。yml

  deployment: red
  

---

另一个等效的结构，使用模式来瞄准组，只会看到主机目标更改为:

- hosts: >-
{{ 'east1[0]' 
if hostvars['localhost'].deployment == 'blue' 
else 'west2[0]' 
}}