Evaluate variable content in Ansible

user_17405153 0
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I load a file with the content Some {{bar}} random text using the file lookup plugin:

- name: Load foo
  set_fact:
    foo: "{{ lookup('file', 'foo.txt') }}"
- name: Output foo
  debug:
    msg: "{{foo}}"

If I output {{foo}}, the output is literally Some {{bar}} random text. Ignoring the fact that I could use the template lookup plugin instead: Is it possible to evaluate {{foo}} after the file has been loaded, so that the actual value of bar will be injected into Some {{bar}} random text?

I am looking for something like:

- name: Evaluate foo
  set_fact:
    evaulated_foo: "{{ lookup('template', foo) }}" #Use the value of foo instead of a file
ansible jinja2
1 Answers

This is the intended behaviour. Lookups return unsafe text, which will never be templated. Use the template lookup when you want to return the contents of a file after template evaluation.

To avoid ordering issues, use a variable with the lookup instead of set_fact. set_fact sets variables to a static, fully evaluated value while normal variables are evaluated lazily, so they don't require that all of the variables be defined at the same time.

- hosts: localhost
  gather_facts: false
  vars:
    foo: "{{ lookup('template', 'test.j2') }}"
  tasks:
    # These will work because bar is a current variable
    - debug:
        msg: "{{ foo }}"
      vars:
        bar: lemon

    - debug:
        msg: "{{ foo }}"
      vars:
        bar: orange

    # This will not work, because bar isn't set
    - set_fact:
        foo: "{{ foo }}"

PLAY [localhost] ***************************************************************

TASK [debug] *******************************************************************
ok: [localhost] => {
    "msg": "Some lemon random text\n"
}

TASK [debug] *******************************************************************
ok: [localhost] => {
    "msg": "Some orange random text\n"
}

TASK [set_fact] ****************************************************************
fatal: [localhost]: FAILED! => {"msg": "The task includes an option with an undefined variable. The error was: {{ lookup('template', 'test.j2') }}: 'bar' is undefined\n\nThe error appears to be in '/home/ec2-user/test.yml': line 18, column 7, but may\nbe elsewhere in the file depending on the exact syntax problem.\n\nThe offending line appears to be:\n\n    # This will not work, because bar isn't set\n    - set_fact:\n      ^ here\n"}
user_154650430
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