fix(helm): omit empty repository segment in bundled image path

[michaelspinks]

What

Fix the bundled-PostgreSQL image helper so an empty image.repository renders a valid reference (registry/name:tag) instead of registry//name:tag, which is an invalid image reference and sends the pod into ImagePullBackOff. I observed this on AKS with Helm Chart 0.9.9.

Why

templates/_helpers.tpl builds the image with a printf that always emits the same registry/repository/name:tag shape — it writes a / between every segment whether or not that segment is empty:

{{- define "kagent.postgresql.image" -}}
{{- $pg := .Values.database.postgres.bundled -}}
{{- printf "%s/%s/%s:%s" $pg.image.registry $pg.image.repository $pg.image.name $pg.image.tag -}}
{{- end -}}

printf "%s/%s/%s:%s" always inserts a / between segments, so an empty repository (a valid configuration for images that live at the root of a registry) leaves an empty path segment and renders a double slash:

docker.io//postgres:18.3-alpine   # invalid reference -> ImagePullBackOff

The kagent.postgresql.image helper is unchanged across v0.9.9, v0.9.10, v0.10.0-beta1, and main (the printf line is identical at each), so the issue affects the current stable line and the next (v0.10.x) release line.

Fix

Build the path as a list, drop empty segments with compact, then join with /. This needs no if/else: an empty registry and/or repository is simply left out, so leaving repository blank produces a valid reference (the supported way to pull an image from the root of a registry) instead of a broken one:

{{- define "kagent.postgresql.image" -}}
{{- $pg := .Values.database.postgres.bundled -}}
{{- $parts := compact (list $pg.image.registry $pg.image.repository $pg.image.name) -}}
{{- printf "%s:%s" (join "/" $parts) $pg.image.tag -}}
{{- end -}}

Rendered results:

registry	repository	name	result
docker.io	library	postgres	docker.io/library/postgres:tag (unchanged)
docker.io	""	postgres	docker.io/postgres:tag (fixed)
""	""	postgres	postgres:tag

Tests

Added one case to helm/kagent/tests/postgresql_test.yaml covering the empty-repository path (developed test-first). The existing default pgvector image and custom image tests already guard the non-empty path, so no regression test was
duplicated.

  - it: should omit empty repository segment in image
    template: postgresql.yaml
    documentIndex: 2
    set:
      database:
        postgres:
          bundled:
            image:
              registry: docker.io
              repository: ""
              name: postgres
              tag: "18.3-alpine"
    asserts:
      - equal:
          path: spec.template.spec.containers[0].image
          value: docker.io/postgres:18.3-alpine
      - notMatchRegex:
          path: spec.template.spec.containers[0].image
          pattern: "//"

The test fails without this change (docker.io//postgres:18.3-alpine) and passes with it — revert the _helpers.tpl hunk to reproduce.

How to verify

make helm-version                                   # generate Chart.yaml from template
helm unittest helm/kagent                           # full suite green (incl. new case)
helm lint helm/kagent

# test-independent reproduction:
helm template t helm/kagent \
  --set database.postgres.bundled.image.repository="" | grep image:
# before: docker.io//postgres:18.3-alpine
# after:  docker.io/postgres:18.3-alpine

Scope

Limited to the bundled-PostgreSQL helper (kagent.postgresql.image), where the // template bug is confirmed. The doc2vec/QueryDoc MCP image lives in a separate chart (helm/tools/querydoc) and is assembled controller-side from IMAGE_REGISTRY / IMAGE_REPOSITORY / IMAGE_TAG env vars, so it is intentionally not changed here. If it exhibits the same // symptom at deploy time, it should be addressed separately (likely in the controller join logic), not in this chart.

A backport to the v0.9.x stable line may be worthwhile since the bug is present there — maintainers' call.

Checklist

• Commit is DCO signed-off (git commit -s).
• helm unittest helm/kagent green; helm lint helm/kagent clean.
• Diff limited to templates/_helpers.tpl and tests/postgresql_test.yaml
  (generated Chart.yaml/Chart.lock/charts/*.tgz/dist/ excluded).
• Test fails without the fix, passes with it.

[Copilot]

Pull request overview

Fixes Helm chart rendering for the bundled PostgreSQL image when database.postgres.bundled.image.repository is empty, avoiding invalid Docker references with a double slash (registry//name:tag) that can lead to ImagePullBackOff.

Changes:

• Update kagent.postgresql.image helper to build the image path from non-empty segments and join with /.
• Add a Helm unittest case to cover the empty-repository scenario and ensure // is not present.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
helm/kagent/templates/_helpers.tpl	Build image reference by compacting empty path segments before joining, preventing registry//name:tag.
helm/kagent/tests/postgresql_test.yaml	Add regression test validating docker.io/postgres:... output when repository is empty.

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