Increase test coverage and refactor parseParameters to ParseParams struct

.gitignore

@@ -13,6 +13,7 @@ Dockerfile.cross
 # Output of the go coverage tool, specifically when used with LiteIDE
 *.out
 coverage.txt
+coverage.html
 
 # Go workspace file
 go.work

Makefile

@@ -39,6 +39,7 @@ vet: ## Vet Go code
 .PHONY: test
 test: tidy fmt vet ## Run tests with coverage
 	go test ./... -race -coverprofile=coverage.out
+	go tool cover -html=coverage.out -o=coverage.html
 
 .PHONY: build
 build: tidy fmt vet test ## Build the binary

cmd/main.go

@@ -34,13 +34,121 @@ const (
 	AnnStatus     = "object-lease-controller.ullberg.io/lease-status"
 )
 
+// ParseParams holds runtime configuration parsed from flags and environment.
+type ParseParams struct {
+	Group                   string
+	Version                 string
+	Kind                    string
+	OptInLabelKey           string
+	OptInLabelValue         string
+	MetricsBindAddress      string
+	HealthProbeBindAddress  string
+	PprofBindAddress        string
+	LeaderElectionEnabled   bool
+	LeaderElectionNamespace string
+}
+
 var (
 	setupLog = ctrl.Log.WithName("setup")
 )
 
+// Allow injection for testing
+var statFn = os.Stat
+var readFileFn = os.ReadFile
+
 func main() {
 	ctrl.SetLogger(zap.New())
 
+	params := parseParameters()
+
+	enableLeaderElection, leaderElectionNamespace, errE := parseLeaderElectionConfig(params.LeaderElectionEnabled, params.LeaderElectionNamespace)
+	if errE != nil {
+		fmt.Printf("%v\n", errE)
+		os.Exit(1)
+	}
+
+	if params.Version == "" || params.Kind == "" {
+		fmt.Println("Usage: lease-controller -group=GROUP -version=VERSION -kind=KIND [--leader-elect] [--leader-elect-namespace=NAMESPACE]")
+		fmt.Println("Or set LEASE_GVK_GROUP, LEASE_GVK_VERSION, LEASE_GVK_KIND, LEASE_LEADER_ELECTION env vars")
+		os.Exit(1)
+	}
+
+	scheme := runtime.NewScheme()
+	_ = corev1.AddToScheme(scheme)
+
+	gvk := schema.GroupVersionKind{
+		Group:   params.Group,
+		Version: params.Version,
+		Kind:    params.Kind,
+	}
+
+	// Use a unique leader election ID per GVK in lower case
+	leaderElectionID := strings.ToLower(fmt.Sprintf("object-lease-controller-%s-%s-%s", params.Group, params.Version, params.Kind))
+
+	mgrOpts := buildManagerOptions(scheme, params.Group, params.Version, params.Kind, params.MetricsBindAddress, params.HealthProbeBindAddress, params.PprofBindAddress, enableLeaderElection, leaderElectionNamespace)
+
+	mgr, err := ctrl.NewManager(ctrl.GetConfigOrDie(), mgrOpts)
+	if err != nil {
+		setupLog.Error(err, "unable to start manager")
+		panic(err)
+	}
+
+	// Create a LeaseWatcher for the specified GVK
+	lw := newLeaseWatcher(mgr, gvk, leaderElectionID)
+
+	if tr, err := configureNamespaceReconciler(mgr, params.OptInLabelKey, params.OptInLabelValue, leaderElectionID); err != nil {
+		setupLog.Error(err, "unable to create controller", "GVK", gvk)
+		panic(err)
+	} else {
+		lw.Tracker = tr
+	}
+
+	// Register the LeaseWatcher with the manager
+	if err := lw.SetupWithManager(mgr); err != nil {
+		setupLog.Error(err, "unable to create controller", "GVK", gvk)
+		panic(err)
+	}
+
+	// Add metrics server expvar handler
+	if params.MetricsBindAddress != "" {
+		setupLog.Info("Adding /debug/vars to metrics", "address", params.MetricsBindAddress)
+		if err := mgr.AddMetricsServerExtraHandler("/debug/vars", expvar.Handler()); err != nil {
+			setupLog.Error(err, "unable to set up metrics server extra handler")
+			os.Exit(1)
+		}
+	}
+
+	healthCheck := func(req *http.Request) error {
+		return healthCheck(req, mgr, gvk)
+	}
+
+	if err := mgr.AddHealthzCheck("gvk", healthCheck); err != nil {
+		setupLog.Error(err, "unable to set up health check")
+		os.Exit(1)
+	}
+
+	// Ready check: verify manager cache is synced
+	readyCheck := func(req *http.Request) error {
+		if !mgr.GetCache().WaitForCacheSync(req.Context()) {
+			return fmt.Errorf("cache not synced")
+		}
+		return nil
+	}
+	if err := mgr.AddReadyzCheck("readyz", readyCheck); err != nil {
+		setupLog.Error(err, "unable to set up ready check")
+		os.Exit(1)
+	}
+
+	setupLog.Info("Starting manager", "group", params.Group, "version", params.Version, "kind", params.Kind, "leaderElectionID", leaderElectionID)
+	if err := mgr.Start(ctrl.SetupSignalHandler()); err != nil {
+		setupLog.Error(err, "problem running manager")
+		panic(err)
+	}
+}
+
+// parseParameters returns a ParseParams struct instead of a tuple to make it
+// easier to extend and pass around in tests.
+func parseParameters() ParseParams {
 	var group, version, kind string
 	var optInLabelKey, optInLabelValue string
 	flag.StringVar(&group, "group", "", "Kubernetes API group (e.g., \"apps\")")
@@ -84,56 +192,71 @@ func main() {
 		optInLabelValue = os.Getenv("LEASE_OPT_IN_LABEL_VALUE")
 	}
 
+	// Leader election may be enabled via env var when not set via flags
+	if !enableLeaderElection {
+		if ele := os.Getenv("LEASE_LEADER_ELECTION"); ele != "" {
+			if strings.EqualFold(ele, "true") || ele == "1" {
+				enableLeaderElection = true
+			}
+		}
+	}
+
+	// If no leader election namespace was provided via flags, allow env fallback.
+	if leaderElectionNamespace == "" {
+		leaderElectionNamespace = os.Getenv("LEASE_LEADER_ELECTION_NAMESPACE")
+	}
+
+	return ParseParams{
+		Group:                   group,
+		Version:                 version,
+		Kind:                    kind,
+		OptInLabelKey:           optInLabelKey,
+		OptInLabelValue:         optInLabelValue,
+		MetricsBindAddress:      metricsAddr,
+		HealthProbeBindAddress:  probeAddr,
+		PprofBindAddress:        pprofAddr,
+		LeaderElectionEnabled:   enableLeaderElection,
+		LeaderElectionNamespace: leaderElectionNamespace,
+	}
+}
+
+// Parse leader election configuration from flags and environment.
+// Returns (enabled, namespace, error)
+func parseLeaderElectionConfig(enableLeaderElection bool, leaderElectionNamespace string) (bool, string, error) {
 	if !enableLeaderElection {
 		if val := os.Getenv("LEASE_LEADER_ELECTION"); val != "" {
 			var err error
 			enableLeaderElection, err = strconv.ParseBool(val)
 			if err != nil {
-				fmt.Printf("Invalid LEASE_LEADER_ELECTION value: %v\n", err)
-				os.Exit(1)
+				return false, "", fmt.Errorf("invalid LEASE_LEADER_ELECTION value: %v", err)
 			}
 
-			// If leader election is enabled, check for namespace and fail if not set and not running in a cluster
 			if enableLeaderElection && leaderElectionNamespace == "" {
 				leaderElectionNamespace = os.Getenv("LEASE_LEADER_ELECTION_NAMESPACE")
 			}
-			if leaderElectionNamespace == "" {
-				// If running outside a cluster, we need a namespace for leader election
-				if _, err := os.Stat("/var/run/secrets/kubernetes.io/serviceaccount/namespace"); os.IsNotExist(err) {
-					fmt.Println("Leader election enabled but LEASE_LEADER_ELECTION_NAMESPACE is not set. Please set it to a valid namespace.")
-					os.Exit(1)
-				} else {
-					// Default to the namespace file if running in a cluster
-					data, _ := os.ReadFile("/var/run/secrets/kubernetes.io/serviceaccount/namespace")
+
+			if enableLeaderElection && leaderElectionNamespace == "" {
+				if _, err := statFn("/var/run/secrets/kubernetes.io/serviceaccount/namespace"); os.IsNotExist(err) {
+					return false, "", fmt.Errorf("leader election enabled but LEASE_LEADER_ELECTION_NAMESPACE is not set; set it to a valid namespace")
+				}
+				// we're in a cluster; default to serviceaccount namespace
+				if data, err := readFileFn("/var/run/secrets/kubernetes.io/serviceaccount/namespace"); err == nil {
 					leaderElectionNamespace = strings.TrimSpace(string(data))
 				}
 			}
 		}
 	}
 
-	if version == "" || kind == "" {
-		fmt.Println("Usage: lease-controller -group=GROUP -version=VERSION -kind=KIND [--leader-elect] [--leader-elect-namespace=NAMESPACE]")
-		fmt.Println("Or set LEASE_GVK_GROUP, LEASE_GVK_VERSION, LEASE_GVK_KIND, LEASE_LEADER_ELECTION env vars")
-		os.Exit(1)
-	}
-
-	scheme := runtime.NewScheme()
-	_ = corev1.AddToScheme(scheme)
-
-	gvk := schema.GroupVersionKind{
-		Group:   group,
-		Version: version,
-		Kind:    kind,
+	if leaderElectionNamespace == "" {
+		leaderElectionNamespace = os.Getenv("LEASE_LEADER_ELECTION_NAMESPACE")
 	}
+	return enableLeaderElection, leaderElectionNamespace, nil
+}
 
-	// Use a unique leader election ID per GVK in lower case
+// Build manager options for a given GVK and flags; extracted for unit testing
+func buildManagerOptions(scheme *runtime.Scheme, group, version, kind string, metricsAddr, probeAddr, pprofAddr string, enableLeaderElection bool, leaderElectionNamespace string) ctrl.Options {
 	leaderElectionID := strings.ToLower(fmt.Sprintf("object-lease-controller-%s-%s-%s", group, version, kind))
-
-	// Set up metrics server options
-	metricsServerOptions := metricsserver.Options{
-		BindAddress: metricsAddr,
-	}
-
+	metricsServerOptions := metricsserver.Options{BindAddress: metricsAddr}
 	mgrOpts := ctrl.Options{
 		Scheme:                        scheme,
 		LeaderElection:                enableLeaderElection,
@@ -143,24 +266,20 @@ func main() {
 		Metrics:                       metricsServerOptions,
 		HealthProbeBindAddress:        probeAddr,
 		Cache: cache.Options{
-			DefaultTransform: util.MinimalObjectTransform(
-				AnnTTL, AnnLeaseStart, AnnExpireAt, AnnStatus,
-			),
+			DefaultTransform: util.MinimalObjectTransform(AnnTTL, AnnLeaseStart, AnnExpireAt, AnnStatus),
 		},
 	}
-
 	if pprofAddr != "" {
 		mgrOpts.PprofBindAddress = pprofAddr
 	}
+	return mgrOpts
+}
 
-	mgr, err := ctrl.NewManager(ctrl.GetConfigOrDie(), mgrOpts)
-	if err != nil {
-		setupLog.Error(err, "unable to start manager")
-		panic(err)
-	}
-
-	// Create a LeaseWatcher for the specified GVK
-	lw := &controllers.LeaseWatcher{
+// Create a LeaseWatcher attached to the given manager. The LeaseWatcher is initialized
+// with default annotations and metrics for the provided GVK. The function does not
+// call SetupWithManager - this is left to the caller.
+func newLeaseWatcher(mgr ctrl.Manager, gvk schema.GroupVersionKind, leaderElectionID string) *controllers.LeaseWatcher {
+	return &controllers.LeaseWatcher{
 		Client:   mgr.GetClient(),
 		GVK:      gvk,
 		Recorder: mgr.GetEventRecorderFor(leaderElectionID),
@@ -172,68 +291,27 @@ func main() {
 		},
 		Metrics: ometrics.NewLeaseMetrics(gvk),
 	}
+}
 
-	if optInLabelKey != "" && optInLabelValue != "" {
-		tracker := util.NewNamespaceTracker()
-
-		nw := &controllers.NamespaceReconciler{
-			Client:     mgr.GetClient(),
-			Recorder:   mgr.GetEventRecorderFor(leaderElectionID),
-			LabelKey:   optInLabelKey,
-			LabelValue: optInLabelValue,
-			Tracker:    tracker,
-		}
-
-		// Register NamespaceReconciler with the manager
-		if err := nw.SetupWithManager(mgr); err != nil {
-			setupLog.Error(err, "unable to create controller", "GVK", gvk)
-			panic(err)
-		}
-
-		lw.Tracker = tracker
-	}
-
-	// Register the LeaseWatcher with the manager
-	if err := lw.SetupWithManager(mgr); err != nil {
-		setupLog.Error(err, "unable to create controller", "GVK", gvk)
-		panic(err)
-	}
-
-	// Add metrics server expvar handler
-	if metricsAddr != "" {
-		setupLog.Info("Adding /debug/vars to metrics", "address", metricsAddr)
-		if err := mgr.AddMetricsServerExtraHandler("/debug/vars", expvar.Handler()); err != nil {
-			setupLog.Error(err, "unable to set up metrics server extra handler")
-			os.Exit(1)
-		}
-	}
-
-	healthCheck := func(req *http.Request) error {
-		return healthCheck(req, mgr, gvk)
-	}
-
-	if err := mgr.AddHealthzCheck("gvk", healthCheck); err != nil {
-		setupLog.Error(err, "unable to set up health check")
-		os.Exit(1)
+// If optInLabelKey and optInLabelValue are provided, create a NamespaceReconciler and
+// register it with the manager. Returns the NamespaceTracker that was created if any,
+// or nil if opt-in was not requested.
+func configureNamespaceReconciler(mgr ctrl.Manager, optInLabelKey, optInLabelValue, leaderElectionID string) (*util.NamespaceTracker, error) {
+	if optInLabelKey == "" || optInLabelValue == "" {
+		return nil, nil
 	}
-
-	// Ready check: verify manager cache is synced
-	readyCheck := func(req *http.Request) error {
-		if !mgr.GetCache().WaitForCacheSync(req.Context()) {
-			return fmt.Errorf("cache not synced")
-		}
-		return nil
-	}
-	if err := mgr.AddReadyzCheck("readyz", readyCheck); err != nil {
-		setupLog.Error(err, "unable to set up ready check")
-		os.Exit(1)
+	tracker := util.NewNamespaceTracker()
+	nw := &controllers.NamespaceReconciler{
+		Client:     mgr.GetClient(),
+		Recorder:   mgr.GetEventRecorderFor(leaderElectionID),
+		LabelKey:   optInLabelKey,
+		LabelValue: optInLabelValue,
+		Tracker:    tracker,
 	}
-
-	setupLog.Info("Starting manager", "group", group, "version", version, "kind", kind, "leaderElectionID", leaderElectionID)
-	if err := mgr.Start(ctrl.SetupSignalHandler()); err != nil {
-		setupLog.Error(err, "problem running manager")
-		panic(err)
+	if err := nw.SetupWithManager(mgr); err != nil {
+		return nil, err
 	}
+	return tracker, nil
 }
 
 // Health check: confirm GVK is discoverable and listable with minimal load