check variable value from host_vars null or not

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I have defined a variable in host_vars/hostname.yml with no value assigned to it. I have the below task defined to check if the variable is empty. My play should fail.

host_vars/hostname.yml

tls_password:

- name: Check for null
  fail: msg="Error value is null"
  when: tls_password == ""

When I run this task it is getting skipped. Any idea how to fix this? Thanks in advance.

ansible
1 Answers

The variable tls_password is not an empty string. It is YAML None equivalent of Python null

    - debug:
        var: tls_password|type_debug

gives

    tls_password|type_debug: NoneType

Therefore the comparison

    - debug:
        msg: '{{ tls_password == "" }}'

will evaluate to false and your task will be skipped

    msg: false

The solution is simple. Test the None value

    - name: Check for null
      fail:
        msg: Error value is null
      when: tls_password == None

gives what you want

fatal: [localhost]: FAILED! => changed=false 
  msg: Error value is null
user_64825610
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