fix: better oci handling

chartvalidator/checker/engine_chart_rendering.go

@@ -88,6 +88,11 @@ func (engine *ChartRenderingEngine) renderSingleChart(chart ChartRenderParams, w
 		return nil, fmt.Errorf("values override file does not exist: %s", chart.ValuesOverride)
 	}
 
+	// Normalize repoURL so that scheme-less OCI references (which ArgoCD
+	// ApplicationSets accept) are treated the same as explicit `oci://` URLs.
+	// See normalizeRepoURL for the rationale.
+	chart.RepoURL = normalizeRepoURL(chart.RepoURL)
+
 	args := []string{
 		"template",
 		chart.ChartName,

chartvalidator/checker/engine_chart_rendering_test.go

@@ -73,6 +73,28 @@ func TestRenderOCIRepo(t *testing.T) {
 	assert.Equal(t, "---\napiVersion: v1\nkind: ConfigMap\nmetadata:\n  name: test\n", string(renderedManifest))
 }
 
+// Scheme-less repoURLs (as used in ArgoCD ApplicationSets that point at GAR /
+// other OCI registries without the oci:// prefix) must be templated as OCI,
+// matching the behaviour of explicit `oci://` URLs.
+func TestRenderOCIRepoNoScheme(t *testing.T) {
+	mockExecutor := createMockExecutor()
+	mockExecutor.Output = []byte("---\napiVersion: v1\nkind: ConfigMap\nmetadata:\n  name: test\n")
+	engine := createEngine(mockExecutor, false)
+	defer cleanupEngine(engine)
+
+	testChart := createTestChart()
+	testChart.RepoURL = "europe-west4-docker.pkg.dev/wallet-dev-462809/interledger-helm-charts"
+	engine.inputChan <- testChart
+
+	result := <-engine.resultChan
+	// Engine normalises RepoURL, so compare against the normalised form.
+	assert.Equal(t, "oci://europe-west4-docker.pkg.dev/wallet-dev-462809/interledger-helm-charts", result.Chart.RepoURL)
+
+	expectedCommand := "helm template test-chart oci://europe-west4-docker.pkg.dev/wallet-dev-462809/interledger-helm-charts/test-chart -f values.yaml -f override.yaml --version 1.0.0 --include-crds --kube-version 1.33.0 --api-versions something --api-versions something-else"
+	actualCommand := mockExecutor.GetFullCommand()
+	assert.Equal(t, expectedCommand, actualCommand)
+}
+
 func TestRenderBaseFileNotExist(t *testing.T) {
 	mockExecutor := createMockExecutor()
 	mockExecutor.FileExistsMap = map[string]bool{

chartvalidator/checker/utils.go

@@ -110,3 +110,27 @@ func findYAMLFiles(dir string) ([]string, error) {
 		return strings.HasSuffix(name, ".yaml") || strings.HasSuffix(name, ".yml")
 	})
 }
+
+// normalizeRepoURL canonicalises an ApplicationSet `repoURL` for use with
+// `helm template --repo`.
+//
+// ArgoCD's ApplicationSet multi-source supports OCI registries with the
+// scheme omitted (e.g. `europe-west4-docker.pkg.dev/.../charts`), and some
+// consumers rely on that form. The helm CLI, however, requires an explicit
+// `oci://` scheme for OCI registries — otherwise it fails with
+// "could not find protocol handler for: <empty>".
+//
+// Heuristic: if the URL has no scheme (no `://`), treat it as OCI and
+// prepend `oci://`. URLs that are clearly HTTP chart repos already carry
+// `http://` or `https://`, and OCI URLs that already carry `oci://` are
+// left untouched.
+func normalizeRepoURL(repoURL string) string {
+	trimmed := strings.TrimSpace(repoURL)
+	if trimmed == "" {
+		return trimmed
+	}
+	if strings.Contains(trimmed, "://") {
+		return trimmed
+	}
+	return "oci://" + trimmed
+}

chartvalidator/checker/utils_test.go

@@ -158,4 +158,25 @@ func createManifestValidationMockExecutor() *MockCommandExecutor {
 		Output: []byte("mocked kubeconform output"),
 		Error:  nil,
 	}
-}
+}
+func TestNormalizeRepoURL(t *testing.T) {
+	cases := []struct {
+		name string
+		in   string
+		want string
+	}{
+		{"empty", "", ""},
+		{"whitespace", "   ", ""},
+		{"https passthrough", "https://example.com/charts", "https://example.com/charts"},
+		{"http passthrough", "http://example.com/charts", "http://example.com/charts"},
+		{"oci passthrough", "oci://europe-west4-docker.pkg.dev/p/r", "oci://europe-west4-docker.pkg.dev/p/r"},
+		{"gar no scheme", "europe-west4-docker.pkg.dev/p/r", "oci://europe-west4-docker.pkg.dev/p/r"},
+		{"ghcr no scheme", "ghcr.io/org/charts", "oci://ghcr.io/org/charts"},
+		{"trims whitespace", "  ghcr.io/org/charts  ", "oci://ghcr.io/org/charts"},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			assert.Equal(t, tc.want, normalizeRepoURL(tc.in))
+		})
+	}
+}