Helm: ensure valid label values when version has digest

[sathieu]

What this PR does / why we need it:

Fix this:

$ helm install loki grafana/loki \
  --set loki.image.tag=2.7.1@sha256:d69f377ecfdbb3f72086a180dcd7c2f02c795cf1867bbeb61606b42a8d41a557
ServiceAccount "loki" is invalid: [
  metadata.labels: Invalid value: "2.7.1@sha256:d69f377ecfdbb3f72086a180dcd7c2f02c795cf1867bbeb61606b42a8d41a557": must be no more than 63 characters,
  metadata.labels: Invalid value: "2.7.1@sha256:d69f377ecfdbb3f72086a180dcd7c2f02c795cf1867bbeb61606b42a8d41a557": 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])?')
],
Service "loki" is invalid: [
  metadata.labels: Invalid value: "2.7.1@sha256:d69f377ecfdbb3f72086a180dcd7c2f02c795cf1867bbeb61606b42a8d41a557": must be no more than 63 characters,
  metadata.labels: Invalid value: "2.7.1@sha256:d69f377ecfdbb3f72086a180dcd7c2f02c795cf1867bbeb61606b42a8d41a557": 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])?')
],
[...]

To ensure it is allowed, and leads to:

      app.kubernetes.io/version: "2.7.1-sha256-d69f377ecfdbb3f72086a180dcd7c2f02c795cf1867bbeb616"

See https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#syntax-and-character-set

(see also https://gitlab.com/kubitus-project/kubitus-installer/-/jobs/3649809256)

Which issue(s) this PR fixes:
Fixes #

Special notes for your reviewer:

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• CHANGELOG.md updated
• Changes that require user attention or interaction to upgrade are documented in docs/sources/upgrading/_index.md

[CLAassistant]

All committers have signed the CLA.

[grafanabot]

./tools/diff_coverage.sh ../loki-target-branch/test_results.txt test_results.txt ingester,distributor,querier,querier/queryrange,iter,storage,chunkenc,logql,loki

Change in test coverage per package. Green indicates 0 or positive change, red indicates that test coverage for a package fell.

+           ingester	0%
+        distributor	0%
+            querier	0%
+ querier/queryrange	0%
+               iter	0%
+            storage	0%
+           chunkenc	0%
+              logql	0%
+               loki	0%

[trevorwhitney]

Thanks for bringing this up, nice find. 2 small questions regarding the implementation, but +1 to moving forward with this.

[trevorwhitney]

2 questions.

1. should we replace it with a : instead of nothing so there's still a visible separator
2. we probably also want to enforce it's truncated to 63 characters?

[sathieu]

Thanks for your review @trevorwhitney.

As : is not allowed, I've replaced it with -. I've moved this to a new defined template "loki.validLabelValue". Back to you 🏓!

[grafanabot]

./tools/diff_coverage.sh ../loki-target-branch/test_results.txt test_results.txt ingester,distributor,querier,querier/queryrange,iter,storage,chunkenc,logql,loki

Change in test coverage per package. Green indicates 0 or positive change, red indicates that test coverage for a package fell.

+           ingester	0%
+        distributor	0%
+            querier	0%
+ querier/queryrange	0%
+               iter	0%
+            storage	0%
+           chunkenc	0%
+              logql	0%
+               loki	0%

[trevorwhitney]

Looks great, thanks for the contribution!