Add DriftIgnoreRules support to flux diff kustomization

Signed-off-by: Dipti Pai <diptipai89@outlook.com>
Assisted-by: GitHub Copilot/Claude Opus 4.7

cmd/flux/diff_kustomization_test.go

@@ -270,3 +270,36 @@ func createObjectFromFile(objectFile string, templateValues map[string]string, t
 
 	return clientObjects
 }
+
+// TestDiffKustomizationDriftIgnoreRules tests `flux diff ks` with drift ignore
+// rules. A service with a drifted port is pre-applied to the cluster, and the
+// kustomization specifies driftIgnoreRules that ignore /spec/ports on Services.
+// The diff should not show the service as drifted.
+func TestDiffKustomizationDriftIgnoreRules(t *testing.T) {
+	tmpl := map[string]string{
+		"fluxns": allocateNamespace("flux-system"),
+	}
+	setupTestNamespace(tmpl["fluxns"], t)
+
+	b, _ := build.NewBuilder("podinfo", "", build.WithClientConfig(kubeconfigArgs, kubeclientOptions))
+	resourceManager, err := b.Manager()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Pre-apply the drifted service (port 9899 instead of 9898) without Flux labels.
+	if _, err := resourceManager.ApplyAll(context.Background(), createObjectFromFile("./testdata/diff-kustomization/drifted-service-no-labels.yaml", tmpl, t), ssa.DefaultApplyOptions()); err != nil {
+		t.Fatal(err)
+	}
+
+	cmd := cmdTestCase{
+		args: "diff kustomization podinfo --path ./testdata/build-kustomization/podinfo --progress-bar=false " +
+			"--kustomization-file ./testdata/diff-kustomization/flux-kustomization-drift-ignore.yaml " +
+			"--ignore-not-found" +
+			" -n " + tmpl["fluxns"],
+		assert: assertGoldenFile("./testdata/diff-kustomization/diff-with-drift-ignore.golden"),
+	}
+	cmd.runTestCmd(t)
+
+	testEnv.DeleteObjectFile("./testdata/diff-kustomization/drifted-service-no-labels.yaml", tmpl, t)
+}

cmd/flux/testdata/diff-kustomization/diff-with-drift-ignore.golden

@@ -0,0 +1,14 @@
+► Deployment/default/podinfo created
+► HorizontalPodAutoscaler/default/podinfo created
+► Service/default/podinfo drifted
+
+metadata
++ one map entry added:
+  labels:
+    kustomize.toolkit.fluxcd.io/name: podinfo
+    kustomize.toolkit.fluxcd.io/namespace:
+
+► Secret/default/docker-secret created
+► Secret/default/secret-basic-auth-stringdata created
+► Secret/default/podinfo-token-77t89m9b67 created
+► Secret/default/db-user-pass-bkbd782d2c created

cmd/flux/testdata/diff-kustomization/drifted-service-no-labels.yaml

@@ -0,0 +1,18 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: podinfo
+  namespace: default
+spec:
+  type: ClusterIP
+  selector:
+    app: podinfo
+  ports:
+    - name: http
+      port: 9899
+      protocol: TCP
+      targetPort: http
+    - port: 9999
+      targetPort: grpc
+      protocol: TCP
+      name: grpc

cmd/flux/testdata/diff-kustomization/flux-kustomization-drift-ignore.yaml

@@ -0,0 +1,19 @@
+---
+apiVersion: kustomize.toolkit.fluxcd.io/v1
+kind: Kustomization
+metadata:
+  name: podinfo
+spec:
+  interval: 5m0s
+  path: ./kustomize
+  force: true
+  prune: true
+  sourceRef:
+    kind: GitRepository
+    name: podinfo
+  targetNamespace: default
+  ignore:
+    - paths:
+        - "/spec/ports"
+      target:
+        kind: Service