var-naming[no-jinja] - why templating variable names is bad?

[Orlik3000]

Hello,

Such a basic example task, with variable name templating:

- name: Templating var
  ansible.builtin.set_fact:
    "prefix_{{ variable1 }}_sufix": "{{ variable2 }}"
  vars:
    variable1: "foo"
    variable2: "bar"

... works fine, but ansible-lint (as expected to current rules) returns:

var-naming[no-jinja]: Variables names must not contain jinja2 templating.

But I cannot find any information why this is actually a bad practice? Could you please explain?

I've only found only a single thing in this topic which is ansible-lint issue (relatively old as from 2021) #1680 , where it seems like templating variables was acceptable at that point of time.
Additionally, ansible-lint finds this violation only when used in playbook, while the same task defined in role is not flagged.

Thanks in advance.

[mdgreenjr]

I am running into this too. Does anyone have any thoughts on this?
My example is more like the following in a role

"{{ variable_name_from_playbook }}": "{{ lookup('ansible.builtin.sometask', **criteria ) }}"
  vars:
    criteria:
      critera1:
      critera2:

[kitos9112]

I don't fully understand why this could not be considered a good use of setting dynamic facts. I guess it's another vector of producing unclean or unpredictable code.

I ended up it skiping the rule altogether

[felipemlemos]

I appreciate all the effort to maintain high standards with ansible-lint rules, but I often find myself puzzled by the lack of explanations for some of these rules, and I believe I am not the only one that uses ansible-lint as a reference to write better ansible code.
This case with templating variable names is a prime example. If using Jinja templating in variable names is considered bad practice, it would be helpful if the documentation could provide clear reasons why.

For instance, Shellcheck does an excellent job at this by not only enforcing rules but also explaining the potential pitfalls of violating them, and even highlighting scenarios where a rule may not apply.
Could ansible-lint consider adopting a similar approach?
The fact that this issue had to be opened underlines the need for more detailed guidelines.

Thank you for considering this feedback.

[stephendorman]

I am also confused by the purpose of this rule. Templating variables is powerful and helpful in many scenarios. Please define why it is undesirable in the documentation.

This rule is joining the skip-list for me.