Allow injecting environment variables into the driver config

[LiquidPL]

I'm trying to deploy democratic-csi using ArgoCD and sealed-secrets, and I'd like to avoid having to seal the entire driver config as a secret. I was wondering if it could be possible to somehow inject values from the environment variables into the config, for example:

driver:
  config:
    driver: freenas-api-nfs
    instance_id:
    httpConnection:
      protocol: http
      host: 10.0.0.1
      port: 80
      apiKey: '{{ env "TRUENAS_API_KEY" }}' # or any other sort of marker that would be picked up by the driver

The value of the apiKey field would then be replaced with the api key pulled from the env vars.

[LiquidPL]

I found out that this can be accomplished directly in the YAML parser using YAML tags: https://github.com/nodeca/js-yaml/blob/master/examples/custom_types.js. it's now handled differently - see PR

I will try sending in a PR to add this.

[rouke-broersma]

This would be great, I have the same setup and the same issue :)