Advanced templating for helm values

[BacLuc]

With the current way of setting helm values via command line we have 2 issues:

1. If the deploy script references an env variable, it may be difficult to not overwrite the value and use the default from values.yaml
2. Passing a cron like schedule is difficult because of globbing.

Possible Solutions:

1. Use a lot of shell if statements (does not solve Problem 1)

2. Use a more powerful templating method:

   1. The deployment github actions just set the env variables they want to set, and then we template a second values file and deploy with that
      values template (here php, we could use any other template engine)

   <? /** @noinspection PhpShortOpenTagInspection */ ?>
   <? if (getenv('IMAGE_TAG')) {?>
   imageTag: "<?=getenv('IMAGE_TAG')?>"
   <?php } ?>
   autoscaling:
     <? if (getenv('AUTOSCALING_ENABLED')) {?>
     enabled: <?=getenv('AUTOSCALING_ENABLED')?>
     <?php } ?>
     minReplicas: 1
     maxReplicas: 5
     targetCPUUtilizationPercentage: 80
     # targetMemoryUtilizationPercentage: 80

   And then in the action:

    env:
      IMAGE_TAG: ${{ inputs.sha }}
      DOMAIN: ${{ inputs.name }}.${{ vars.DOMAIN }}
    run: |
       env > /tmp/.env
       docker run --rm --env-file /tmp/.env -v $(pwd)/.helm/deploy-values.yaml.php:/values.yaml.php php -f /values.yaml.php > deploy-values.yaml
       helm upgrade --install ecamp3-${{ inputs.name }} .  -f deploy-values.yaml
      ....