Allow digests in image tag

[blueprismo]

I would love to add digests or tag@digest in the docker images in the vector helm chart.

State of the art

❯ helm template . | grep image -A2-B2
      containers:
        - name: vector
          image: "timberio/vector:0.50.0-distroless-libc" # OK 
          imagePullPolicy: IfNotPresent
          args:
❯ helm template . --set "image.tag=sha256:f1a9f6524acd729d532c2ff0effb6f3254a8237b906985a250e60c5571dca1aa" | grep image -A2 -B2
      containers:
        - name: vector
          image: "timberio/vector:sha256:f1a9f6524acd729d532c2ff0effb6f3254a8237b906985a250e60c5571dca1aa" #Fails with incorrect image name
          imagePullPolicy: IfNotPresent
          args:

Desired state

Allow image.tag to populate the cases with;

• tag only: repo:tag
• sha only: repo@sha256:…
• tag@digest: repo:tag@sha256:…

# tag only
❯ helm template . --set "image.tag=latest" | grep "image:"
          image: "timberio/vector:latest"

# tag@digest
❯ helm template . --set "image.tag=latest@sha256:f1a9f6524acd729d532c2ff0effb6f3254a8237b906985a250e60c5571dca1aa" | grep "image:"
          image: "timberio/vector:latest@sha256:f1a9f6524acd729d532c2ff0effb6f3254a8237b906985a250e60c5571dca1aa"

# sha only:
❯ helm template . --set "image.tag=sha256:f1a9f6524acd729d532c2ff0effb6f3254a8237b906985a250e60c5571dca1aa" | grep "image:"
          image: "timberio/vector@sha256:f1a9f6524acd729d532c2ff0effb6f3254a8237b906985a250e60c5571dca1aa"

# default Chart.appVersion
❯ helm template . | grep "image:"
          image: "timberio/vector:0.50.0-distroless-libc"

## backwards compatible image.sha field
helm template . --set "image.repository=test/test" --set "image.sha=sha256:f1a9f6524acd729d532c2ff0effb6f3254a8237b906985a250e60c5571dca1aa" | grep "image:"
          image: "test/test:0.50.0-distroless-libc@sha256:f1a9f6524acd729d532c2ff0effb6f3254a8237b906985a250e60c5571dca1aa"

[pront]

Hi @blueprismo, this is a good idea.

[blueprismo]

Thanks for the fast responses!
Friendly ping @pront @thomasqueirozb