Ansible, set_fact using if then else statement

问题

I am trying to set a variable in Ansible with set_fact at runtime based upon another variable. If uses first value no matter what the actual value is. Here is my code example:

- name: Global_vars - get date info
    set_fact:  
      jm_env: "{{lookup('env', 'Environment')}}"
      l_env: "{% if '{{jm_env}}==Develop' %}d{% elif '{{jm_env}}==Staging'%}s{% else %}p{% endif %}"

l_env is d no matter what jm_env is set.

回答1:

Firstly, dictionaries in YAML are not ordered (and the syntax used by Ansible here is a YAML dictionary), so you have no guarantee Ansible would first set jm_env before proceeding to l_env -- you need to split the assignment into two tasks.

Secondly, your test expressions are incorrect -- '{{jm_env}}==Develop' is a string because it is quoted; and testing if 'string' will always evaluate to true (this is the direct reason you always get d in the output).

Use:

- name: Set the jm_env
    set_fact:  
      jm_env: "{{lookup('env', 'Environment')}}"

- name: Set the l_env
    set_fact:  
      l_env: "{% if jm_env=='Develop' %}d{% elif jm_env=='Staging'%}s{% else %}p{% endif %}"

回答2:

One of the simple way to set fact based condition example as follows:

  - name: Set facts for delete operation results
    set_fact:
        tr_result: "{{ '{\"status\": \"SUCCESS\"}' if (op_result['output'] == 'Deleted') else '{\"status\" : \"FAILED\"}' }}"

Note: Assume op_result is a dict & already defined.

Code has been tested and working well.

来源：https://stackoverflow.com/questions/42935820/ansible-set-fact-using-if-then-else-statement