Better connection strings

[egabancho]

No description provided.

[egabancho]

@lindhe What do you think about something like this? It should somehow address #112

[lindhe]

Wow. Maybe. 👀 The logic with defining each part as a separate env is sound, no issues there. But composing a new env value based on other envs like this, I'm unfamiliar with. If it works as your code indicates, then yeah I think this looks very promising.

How does this work? Does Kubernetes support the $(ENV) syntax in string values, or does that happen inside the container? I feel lost as to why this works. 😅 I assumed you tried it and it seems to work?

Assuming it works, I really like this because I think it should be forwards-compatible with inveniosoftware/invenio-config#57 and/or inveniosoftware/invenio-app-rdm#2918 which is nice.

[egabancho]

# compose-env.yaml
---
apiVersion: v1
data:
  secret: c2VjcmV0 # secret
kind: Secret
metadata:
  name: compose-env
---
apiVersion: v1
kind: Pod
metadata:
  name: compose-env
spec:
  containers:
  - name: compose-env
    image: bash
    env:
    - name: SECRET
      valueFrom:
          secretKeyRef:
            name: compose-env
            key: secret
    - name: PLAIN
      value: plain
    - name: MESSAGE
      value: "$(PLAIN) - $(SECRET)"
    command: ["echo"]
    args: ["$(MESSAGE)"]

$ kubectl apply -f compose-env.yaml
secret/compose-env created
pod/compose-env created

$ kubectl logs compose-env
plain - secret

It does work 😅
https://kubernetes.io/docs/tasks/inject-data-application/define-environment-variable-container/#using-environment-variables-inside-of-your-config

[egabancho]

I am not sure when it happens, in particular after reading this in the docs Variables making use of others defined in the same context must come later in the list..
I would think the interpolation happens at run time inside the container. This Environment section of the output of kubectl describe pod

     Environment:
      SECRET:   <set to the key 'secret' in secret 'compose-env'>  Optional: false
      PLAIN:    plain
      MESSAGE:  $(PLAIN) - $(SECRET)

[lindhe]

Sounds convincing! Wow, this is so powerful (and a bit confusing)! 😀

I think this would be a great first step towards handling connection credentials better!