Question:
I want to conditionally define a variable in an Ansible playbook like this:
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my_var: "{{ 'foo' if my_condition}}" |
I would like the variable to remain undefined if the condition does not resolve to true.
Ansible gives the following error if I try to execute the code:
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fatal: [foo.local] => {'msg': 'AnsibleUndefinedVariable: One or more undefined variables: the inline if-expression on line 1 evaluated to false and no else section was defined.', 'failed': True} |
Why is this an error anyway?
The complete case looks like this:
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{role: foo, my_var: "foo"} |
If my_var is defined, the role does something special. In some cases, I don’t want the role to do this. I could use when: condition, but then I would have to copy the whole role block. I could also use an extra bool variable, but I would like a solution without having to change the “interface” to the role.
Any ideas?
Answer:
You could use something like this:
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my_var: "{{ 'foo' if my_condition else '' }}" |
The ‘else’ will happen if condition not match, and in this case will set a empty value for the variable. I think this is a short, readable and elegant solution.