How can I use a condition to set a variable value in Ansible?

Question

I have two variables: a, b.

I want to assign a value to a variable c based on which: a or b contains greater numerical value.

This what I tried:

- set_fact:
    c: "test1"
  when: a <= b

- set_fact:
    c: "test2"
  when: b <= a

Look like it always sets c to test1 not test2.

Answer 1

• Using if-else expression:

  - set_fact:
      c: "{{ 'test1' if (a >= b) else 'test2' }}"
  

• Using ternary operator:

  - set_fact:
      c: "{{ (a >= b) | ternary ('test1', 'test2') }}"
  

• Using your own code which is correct (see the notice below)

---

Either of the above methods requires both variables used in comparison to be of the same type to give sensible results. And for a numerical comparison, they require both values to be integers.

The code from the question:

- set_fact:
    c: "test1"
  when: a <= b

- set_fact:
    c: "test2"
  when: b <= a

works properly in two cases:

• both: a and b are integers
• both: a and b are strings containing numerical value with the same number of digits

However it produces unexpected result is when:

• one of the values is string and the other integer
• the string values contain numerical values with different number of digits