fix: helm values write-back for multi-source apps (#1289) (#1293)

Signed-off-by: Cheng Fang <[email protected]>
Co-authored-by: Claude <[email protected]>

Author: chengfang

pkg/argocd/update.go

@@ -455,6 +455,21 @@ func marshalParamsOverride(app *v1alpha1.Application, originalData []byte) ([]by
 	appType := GetApplicationType(app)
 	appSource := getApplicationSource(app)
 
+	// Special handling for multi-source applications with helmvalues write-back target
+	// We need to ensure we get the Helm source, not the Kustomize source
+	if strings.HasPrefix(app.Annotations[common.WriteBackTargetAnnotation], common.HelmPrefix) {
+		// For helmvalues write-back, we need the Helm source specifically
+		if app.Spec.HasMultipleSources() {
+			for _, s := range app.Spec.Sources {
+				if s.Helm != nil {
+					appSource = &s
+					appType = ApplicationTypeHelm
+					break
+				}
+			}
+		}
+	}
+
 	switch appType {
 	case ApplicationTypeKustomize:
 		if appSource.Kustomize == nil {

pkg/argocd/update_test.go

@@ -2242,6 +2242,82 @@ replicas: 1
 		assert.Error(t, err)
 	})
 
+	t.Run("Multi-source application with Kustomize first and Helm values write-back", func(t *testing.T) {
+		// This reproduces issue #1289 where getApplicationSource returns the Kustomize source
+		// instead of the Helm source for multi-source applications
+		expected := `
+# auto generated by argocd image updater
+
+theme:
+  image:
+    tag: latest
+    name: docker.io/hello-world
+`
+		app := v1alpha1.Application{
+			ObjectMeta: v1.ObjectMeta{
+				Name: "multi-source-app",
+				Annotations: map[string]string{
+					"argocd-image-updater.argoproj.io/image-list":            "theme=docker.io/hello-world:latest",
+					"argocd-image-updater.argoproj.io/write-back-method":     "git",
+					"argocd-image-updater.argoproj.io/write-back-target":     "helmvalues:/apps/test/theme-version.yaml",
+					"argocd-image-updater.argoproj.io/theme.helm.image-name": "theme.image.name",
+					"argocd-image-updater.argoproj.io/theme.helm.image-tag":  "theme.image.tag",
+				},
+			},
+			Spec: v1alpha1.ApplicationSpec{
+				Sources: []v1alpha1.ApplicationSource{
+					{
+						// First source: Kustomize (this gets picked up by getApplicationSource!)
+						Path:      "apps/test/overlays/dev",
+						RepoURL:   "https://example.com/gitops.git",
+						Kustomize: &v1alpha1.ApplicationSourceKustomize{
+							// Empty kustomize
+						},
+					},
+					{
+						// Second source: Helm chart (this is what we want!)
+						Chart:   "my-chart",
+						RepoURL: "https://example.com/charts",
+						Helm: &v1alpha1.ApplicationSourceHelm{
+							Parameters: []v1alpha1.HelmParameter{
+								{
+									Name:        "theme.image.name",
+									Value:       "docker.io/hello-world",
+									ForceString: true,
+								},
+								{
+									Name:        "theme.image.tag",
+									Value:       "latest",
+									ForceString: true,
+								},
+							},
+						},
+					},
+				},
+			},
+			Status: v1alpha1.ApplicationStatus{
+				SourceTypes: []v1alpha1.ApplicationSourceType{
+					v1alpha1.ApplicationSourceTypeKustomize,
+					v1alpha1.ApplicationSourceTypeHelm,
+				},
+				Summary: v1alpha1.ApplicationSummary{
+					Images: []string{
+						"docker.io/hello-world:latest",
+					},
+				},
+			},
+		}
+
+		// Simulate creating a new file (nil originalData)
+		yamlOutput, err := marshalParamsOverride(&app, nil)
+		require.NoError(t, err)
+		assert.NotEmpty(t, yamlOutput, "output should not be empty")
+
+		// The output should contain the helm values, not be empty
+		yamlStr := string(yamlOutput)
+		assert.Equal(t, strings.TrimSpace(strings.ReplaceAll(expected, "\t", "  ")), strings.TrimSpace(yamlStr))
+	})
+
 	t.Run("Whitespace only values file from helm source does not cause error", func(t *testing.T) {
 		expected := `
 # auto generated by argocd image updater
@@ -2302,10 +2378,22 @@ nginx:
 
 		originalData := []byte(`
 `)
-		yaml, err := marshalParamsOverride(&app, originalData)
+		yamlOutput, err := marshalParamsOverride(&app, originalData)
 		require.NoError(t, err)
-		assert.NotEmpty(t, yaml)
-		assert.Equal(t, strings.TrimSpace(strings.ReplaceAll(expected, "\t", "  ")), strings.TrimSpace(string(yaml)))
+		assert.NotEmpty(t, yamlOutput)
+		assert.Equal(t, strings.TrimSpace(strings.ReplaceAll(expected, "\t", "  ")), strings.TrimSpace(string(yamlOutput)))
+
+		// Verify round-trip: marshal → unmarshal → marshal
+		// This ensures the generated YAML structure can be read back correctly
+		var roundTripNode yaml.Node
+		err = yaml.Unmarshal(yamlOutput, &roundTripNode)
+		require.NoError(t, err, "should be able to unmarshal the generated YAML")
+
+		roundTripYaml, err := yaml.Marshal(&roundTripNode)
+		require.NoError(t, err, "should be able to re-marshal the unmarshaled YAML")
+		assert.NotEmpty(t, roundTripYaml, "round-tripped YAML should not be empty")
+
+		assert.YAMLEq(t, string(yamlOutput), string(roundTripYaml), "round-tripped YAML should be semantically equivalent")
 	})
 }