Environment variables support in Pyrra

[lukasmrtvy]

Would be great to support env vars in Pyrra, for example:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: pyrra-api
  namespace: monitoring
spec:
  template:
    spec:
      containers:
        - name: pyrra
          env:
          - name: PASSWORD
            valueFrom:
              secretKeyRef:
                name: secrets
                key: password
          args:
            - api
            - --log-level=info
            - --prometheus-url=http://mimir-gateway.mimir:80/prometheus
            - --prometheus-basic-auth-password=$PASSWORD
            - --prometheus-basic-auth-username=mimir
            - --api-url=http://pyrra-kubernetes:9444

[metalmatze]

We could implement something like that, however, just like Prometheus, I'm in favour to use files containing passwords. Do you think using files would work too?

[mtthwcmpbll]

I was exploring this today as we're also trying to connect to a mimir gatewat behind basic augh, and I was able to get the environment variable approach to work if I included parentheses around my environment variables in my args:

spec:
  containers:
  - args:
    - api
    - --api-url=http://pyrra-kubernetes.monitoring.svc.cluster.local:9444
    - --prometheus-url=http://mimir-gateway.monitoring.svc.cluster.local/prometheus
    - --prometheus-basic-auth-username=$(OBSERVABILITY_USERNAME)
    - --prometheus-basic-auth-password=$(OBSERVABILITY_PASSWORD)
    env:
    - name: OBSERVABILITY_USERNAME
      valueFrom:
        secretKeyRef:
          key: username
          name: observability-credentials
    - name: OBSERVABILITY_PASSWORD
      valueFrom:
        secretKeyRef:
          key: password
          name: observability-credentials

For my particular use case, I need to use kustomize on the Pyrra-provided manifests in order to patch those environment variables in and then add the additional args to the existings ones in the provided manifests. I'm not sure how Pyrra would expect to pull a secret from a file, but it seems like that would work here too with a combinations of volumes and a way to point Pyrra at the right file.