feat(helm): allow specifying operator image digest

[jimrollenhagen]

Why

Users should be able to specify immutable image specs, which only digest allows (image tags are mutable).

What

Added a template helper to build the image spec, which uses digest if set, and tag if not, falling back to the existing default.

Tested this by using helm template to render old.yaml without my changes, and comparing it to various iterations of helm template with values specified.

clickhouse-operator > helm template clickhouse-operator dist/chart > new.yaml
clickhouse-operator > helm template clickhouse-operator --set "manager.image.tag=v0.0.2" dist/chart > with-tag-only.yaml
clickhouse-operator > helm template clickhouse-operator --set "manager.image.digest=sha256:abc123" dist/chart > with-digest-only.yaml
clickhouse-operator > helm template clickhouse-operator --set "manager.image.tag=v0.0.2" --set "manager.image.digest=sha256:abc123" dist/chart > with-both.yaml
clickhouse-operator > helm template clickhouse-operator --set "manager.image.repository=example.com/clickhouse-operator" --set "manager.image.digest=sha256:abc123" dist/chart > with-repo.yaml
clickhouse-operator > diff old.yaml new.yaml
clickhouse-operator > diff old.yaml with-tag-only.yaml
8826c8826
<                   image: "ghcr.io/clickhouse/clickhouse-operator:latest"
---
>                   image: "ghcr.io/clickhouse/clickhouse-operator:v0.0.2"
clickhouse-operator > diff old.yaml with-digest-only.yaml
8826c8826
<                   image: "ghcr.io/clickhouse/clickhouse-operator:latest"
---
>                   image: "ghcr.io/clickhouse/clickhouse-operator@sha256:abc123"
clickhouse-operator > diff old.yaml with-both.yaml
8826c8826
<                   image: "ghcr.io/clickhouse/clickhouse-operator:latest"
---
>                   image: "ghcr.io/clickhouse/clickhouse-operator@sha256:abc123"
clickhouse-operator > diff old.yaml with-repo.yaml
8826c8826
<                   image: "ghcr.io/clickhouse/clickhouse-operator:latest"
---
>                   image: "example.com/clickhouse-operator@sha256:abc123"

Related Issues

[CLAassistant]

All committers have signed the CLA.

[GrigoryPervakov]

Hi @jimrollenhagen, thank you for your contribution. Can you sign a CLA?

[jroll-stripe]

Hi @jimrollenhagen, thank you for your contribution. Can you sign a CLA?

Thanks for approving! I'm waiting on an ack from employer, but I will sign as soon as I get that and ping you :)

[jimrollenhagen]

@GrigoryPervakov it's signed now, sorry for the wait!