Ansible: how to construct a variable from another variable and then fetch it’s value


Here is my problem I need to use one variable ‘target_host’ and then append ‘_host’ to it’s value to get another variable name whose value I need.
If you look at my playbook. Task nbr 1,2,3 fetch the value of variable however nbr 4 is not able to do what I expect. Is there any other way to achieve the same in ansible?


This (AFAIK) isn’t possible. The primary limitation that stops us doing this (no matter how you spin it), is ‘variable expansion’ in ansible is a single pass process and what you want requires multiple-passes.

Only [seriously hacky] ways I can think of are:

  • Create the playbook dynamically from your playbook using template and execute it.
  • I heard that Jinja2 engine does multi-pass evaluation. May be if you put these strings in a template and then use the lookup('template', ...) filter. Unfortunately I have no experience with Jinja2 templates so not quite sure if this is even an option.

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