Alloy helmchart image configuration is not compatible with renovate bot

[taraspos]

What's wrong?

Renovate bot supports detecting docker images in helm values files¹ that follow conventional format like:

image:
  repository: 'some-docker/dependency'
  tag: v1.0.0
  registry: registry.example.com # optional key, will default to "docker.io"

However, Alloy charts are not compatible with this format due to the additional digest field and un-conventional usage of tag property:

• alloy/operations/helm/charts/alloy/values.yaml

  Lines 123 to 132 in f0211d0

  	image:
  	# -- Grafana Alloy image registry (defaults to docker.io)
  	registry: "docker.io"
  	# -- Grafana Alloy image repository.
  	repository: grafana/alloy
  	# -- (string) Grafana Alloy image tag. When empty, the Chart's appVersion is
  	# used.
  	tag: null
  	# -- Grafana Alloy image's SHA256 digest (either in format "sha256:XYZ" or "XYZ"). When set, will override `image.tag`.
  	digest: null

Renovate bot detects helm-values file and tries to replace tag value:

- tag: v1.4.3
+ tag: v1.4.3@sha256:06bdcbb51fc22b16c2e96b31cbdf9cb0972e3bdedfbac2cc55ed36743f7fb9aa

However, Alloy helm chart expects sha256 to be set in digest field. Attempt to set digest to null and provide digest as part of tag fails with:

metadata.labels: Invalid value: "v1.4.3@sha256:": a valid label must be an empty string or consist of alphanumeric characters, '-', '' or '.', and must start and end with an alphanumeric character (e.g. 'MyValue', or 'my_value', or '12345', regex used for validation is '(([A-Za-z0-9][-A-Za-z0-9.])?[A-Za-z0-9])?')

Because helm chart logic tries to get value from tag and add it to the labels:

alloy/operations/helm/charts/alloy/templates/_helpers.tpl

Lines 58 to 61 in f0211d0

	{{/* substr trims delimeter prefix char from alloy.imageId output
	e.g. ':' for tags and '@' for digests.
	For digests, we crop the string to a 7-char (short) sha. */}}
	app.kubernetes.io/version: {{ (include "alloy.imageId" .) | trunc 15 | trimPrefix "@sha256" | trimPrefix ":" | quote }}

Steps to reproduce

Configure renovate bot to watch alloy's values file

System information

No response

Software version

No response

Configuration

Logs

Footnotes

1. https://docs.renovatebot.com/modules/manager/helm-values/ ↩