Support variables substitution in deploy.kubernetes.template file paths

[JulienFS]

I need to deploy different kubernetes certificates depending on build target (staging/dev).
I wish I could use an env variable in the DMakefile to specifcy the path like so :

env:
  default:
    variables:
      MY_CERT_PATH: option_1.yml
  branches:
    staging:
      variables:
        MY_CERT_PATH: option_2.yml
...
kubernetes:
  - template: ${MY_CERT_PATH}

But it seems that variables are not allowed here.
I tried to work around by using the branch selector for stages but since '*' stands for every branch and not for a "case else" for matched branches I would end up deploying both certificates when deploying on staging.

[thomas-riccardi]

What we usually do is go for the variable part of the yaml moved up in dmake.yml as a dmake kubernetes template variable, and up to the per-branch .env in dmake.yml.
It's not perfect, but it works.

The support for variables in the template path could indeed be added, but you'd need to always make it point to something valid, for all branches, and it would not help for for-some-branches manifests. I'm not sure if it would help a lot.
(Also, adding variable substitution here makes the early dmake.yml validation undoable: it'd be deferred at planning time, which is doable but not great.)