正确的方式/语法，如果在主机的ansible剧本中创建if ... else语句

Question

I try to create a conditional logic to run against different group of nodes based on the environment variable "branch" I pass in from the command line.

Below is my code sample. branch is the variable I pass in. If branch == 'test', I will pick the group 'upgrade-CI-test' as targeted_host for my next task, anything other than test will retain the value of the variable "upgrade_version"

However, I can't get my play "Remove old scripts from upgrade machine" executed on the test group for some reasons. I'm not sure if that's the correct the set up variable? I'm new to ansible, any hints will be appreciated.

---
- name: Set targeted hosts based on git branch
  hosts: localhost
  tasks:
  - name: Set hosts variable
    vars:
      targeted_host: "{{groups['upgrade-CI-test'] if branch == 'test' else upgrade_version }}"
    debug:
      var: targeted_host
- name: Remove old scripts from upgrade machine
  hosts:  targeted_host
  tasks:
  - name: Remove any old wrapper scripts
    win_file:
      path: D:\my_path
      state: absent

Answer 1

If you have branch and upgrade_version variables defined at playbook parse time, then you can do:

---
- name: Remove old scripts from upgrade machine
  hosts: "{{ 'upgrade-CI-test' if branch == 'test' else upgrade_version }}"
  tasks:
    - name: Remove any old wrapper scripts
      win_file:
        path: D:\my_path
        state: absent

Update: if you have multiple plays, you can use group_by to make dynamic group and use it for your plays.

---
- name: Make dynamic group
  hosts: "{{ 'upgrade-CI-test' if branch == 'test' else upgrade_version }}"
  tasks:
    - group_by:
        key: my_new_group

- name: Remove old scripts from upgrade machine
  hosts: my_new_group
  tasks:
    - name: Remove any old wrapper scripts
      win_file:
        path: D:\my_path
        state: absent

- name: Do some other stuff
  hosts: my_new_group
  tasks:
    - debug:
        msg: hello