backend: Refactor createHeadlampHandler to reduce complexity

backend/cmd/headlamp.go

@@ -400,57 +400,28 @@ func addPluginListRoute(config *HeadlampConfig, r *mux.Router) {
 	}).Methods("GET")
 }
 
-//nolint:gocognit,funlen,gocyclo
-func createHeadlampHandler(config *HeadlampConfig) http.Handler {
-	kubeConfigPath := config.KubeConfigPath
-
-	config.StaticPluginDir = os.Getenv("HEADLAMP_STATIC_PLUGINS_DIR")
-
-	logger.Log(logger.LevelInfo, nil, nil, "Creating Headlamp handler")
-	logger.Log(logger.LevelInfo, nil, nil, "Listen address: "+fmt.Sprintf("%s:%d", config.ListenAddr, config.Port))
-	logger.Log(logger.LevelInfo, nil, nil, "Kubeconfig path: "+kubeConfigPath)
-	logger.Log(logger.LevelInfo, nil, nil, "Static plugin dir: "+config.StaticPluginDir)
-	logger.Log(logger.LevelInfo, nil, nil, "Plugins dir: "+config.PluginDir)
-	logger.Log(logger.LevelInfo, nil, nil, "Dynamic clusters support: "+fmt.Sprint(config.EnableDynamicClusters))
-	logger.Log(logger.LevelInfo, nil, nil, "Helm support: "+fmt.Sprint(config.EnableHelm))
-	logger.Log(logger.LevelInfo, nil, nil, "Proxy URLs: "+fmt.Sprint(config.ProxyURLs))
-
+// setupPluginHandlers initializes the plugin cache and sets up handlers for plugins.
+func setupPluginHandlers(config *HeadlampConfig, skipFunc kubeconfig.ShouldBeSkippedFunc) {
 	plugins.PopulatePluginsCache(config.StaticPluginDir, config.PluginDir, config.cache)
 
-	skipFunc := kubeconfig.SkipKubeContextInCommaSeparatedString(config.SkippedKubeContexts)
-
 	if !config.UseInCluster || config.WatchPluginsChanges {
-		// in-cluster mode is unlikely to want reloading plugins.
 		pluginEventChan := make(chan string)
 		go plugins.Watch(config.PluginDir, pluginEventChan)
 		go plugins.HandlePluginEvents(config.StaticPluginDir, config.PluginDir, pluginEventChan, config.cache)
-		// in-cluster mode is unlikely to want reloading kubeconfig.
-		go kubeconfig.LoadAndWatchFiles(config.KubeConfigStore, kubeConfigPath, kubeconfig.KubeConfig, skipFunc)
+		go kubeconfig.LoadAndWatchFiles(config.KubeConfigStore, config.KubeConfigPath, kubeconfig.KubeConfig, skipFunc)
 	}
+}
 
-	// In-cluster
-	if config.UseInCluster {
-		context, err := kubeconfig.GetInClusterContext(config.oidcIdpIssuerURL,
-			config.oidcClientID, config.oidcClientSecret,
-			strings.Join(config.oidcScopes, ","),
-			config.oidcSkipTLSVerify,
-			config.oidcCACert)
-		if err != nil {
-			logger.Log(logger.LevelError, nil, err, "Failed to get in-cluster context")
-		}
-
-		context.Source = kubeconfig.InCluster
+//nolint:gocognit,funlen,gocyclo
+func createHeadlampHandler(config *HeadlampConfig) http.Handler {
+	kubeConfigPath := config.KubeConfigPath
 
-		err = context.SetupProxy()
-		if err != nil {
-			logger.Log(logger.LevelError, nil, err, "Failed to setup proxy for in-cluster context")
-		}
+	config.StaticPluginDir = os.Getenv("HEADLAMP_STATIC_PLUGINS_DIR")
 
-		err = config.KubeConfigStore.AddContext(context)
-		if err != nil {
-			logger.Log(logger.LevelError, nil, err, "Failed to add in-cluster context")
-		}
-	}
+	logStartupInfo(config)
+	skipFunc := kubeconfig.SkipKubeContextInCommaSeparatedString(config.SkippedKubeContexts)
+	setupPluginHandlers(config, skipFunc)
+	setupInClusterContext(config)
 
 	if config.StaticDir != "" {
 		baseURLReplace(config.StaticDir, config.BaseURL)
@@ -838,6 +809,45 @@ func createHeadlampHandler(config *HeadlampConfig) http.Handler {
 	return r
 }
 
+// logStartupInfo logs config information of the Headlamp server.
+func logStartupInfo(config *HeadlampConfig) {
+	logger.Log(logger.LevelInfo, nil, nil, "Creating Headlamp handler")
+	logger.Log(logger.LevelInfo, nil, nil, "Listen address: "+fmt.Sprintf("%s:%d", config.ListenAddr, config.Port))
+	logger.Log(logger.LevelInfo, nil, nil, "Kubeconfig path: "+config.KubeConfigPath)
+	logger.Log(logger.LevelInfo, nil, nil, "Static plugin dir: "+config.StaticPluginDir)
+	logger.Log(logger.LevelInfo, nil, nil, "Plugins dir: "+config.PluginDir)
+	logger.Log(logger.LevelInfo, nil, nil, "Dynamic clusters support: "+fmt.Sprint(config.EnableDynamicClusters))
+	logger.Log(logger.LevelInfo, nil, nil, "Helm support: "+fmt.Sprint(config.EnableHelm))
+	logger.Log(logger.LevelInfo, nil, nil, "Proxy URLs: "+fmt.Sprint(config.ProxyURLs))
+}
+
+// setupInClusterContext prepares in-cluster context with OIDC authentication,
+// sets up a proxy and adds it to the kubeconfig store.
+func setupInClusterContext(config *HeadlampConfig) {
+	if config.UseInCluster {
+		context, err := kubeconfig.GetInClusterContext(config.oidcIdpIssuerURL,
+			config.oidcClientID, config.oidcClientSecret,
+			strings.Join(config.oidcScopes, ","),
+			config.oidcSkipTLSVerify,
+			config.oidcCACert)
+		if err != nil {
+			logger.Log(logger.LevelError, nil, err, "Failed to get in-cluster context")
+		}
+
+		context.Source = kubeconfig.InCluster
+
+		err = context.SetupProxy()
+		if err != nil {
+			logger.Log(logger.LevelError, nil, err, "Failed to setup proxy for in-cluster context")
+		}
+
+		err = config.KubeConfigStore.AddContext(context)
+		if err != nil {
+			logger.Log(logger.LevelError, nil, err, "Failed to add in-cluster context")
+		}
+	}
+}
+
 func parseClusterAndToken(r *http.Request) (string, string) {
 	cluster := ""
 	re := regexp.MustCompile(`^/clusters/([^/]+)/.*`)

backend/pkg/kubeconfig/kubeconfig.go

@@ -969,7 +969,7 @@ func GetInClusterContext(oidcIssuerURL string,
 
 // Func type for context filter, if the func return true,
 // the context will be skipped otherwise the context will be used.
-type shouldBeSkippedFunc = func(kubeContext Context) bool
+type ShouldBeSkippedFunc = func(kubeContext Context) bool
 
 // AllowAllKubeContext will keep all contexts.
 func AllowAllKubeContext(_ Context) bool {
@@ -980,7 +980,7 @@ func AllowAllKubeContext(_ Context) bool {
 // whose names are in the given comma-separated string.
 // For example, if pass the "a,b" for blackKubeContextNameStr,
 // the contexts named "a" and "b" will be skipped.
-func SkipKubeContextInCommaSeparatedString(blackKubeContextNameStr string) shouldBeSkippedFunc {
+func SkipKubeContextInCommaSeparatedString(blackKubeContextNameStr string) ShouldBeSkippedFunc {
 	blackKubeContextNameList := strings.Split(blackKubeContextNameStr, ",")
 	blackKubeContextNameMap := map[string]bool{}
 
@@ -999,7 +999,7 @@ func SkipKubeContextInCommaSeparatedString(blackKubeContextNameStr string) shoul
 // Note: No need to remove contexts from the store, since
 // adding a context with the same name will overwrite the old one.
 func LoadAndStoreKubeConfigs(kubeConfigStore ContextStore, kubeConfigs string, source int,
-	ignoreFunc shouldBeSkippedFunc,
+	ignoreFunc ShouldBeSkippedFunc,
 ) error {
 	var errs []error //nolint:prealloc
 

backend/pkg/kubeconfig/watcher.go

@@ -14,7 +14,7 @@ import (
 const watchInterval = 10 * time.Second
 
 // LoadAndWatchFiles loads kubeconfig files and watches them for changes.
-func LoadAndWatchFiles(kubeConfigStore ContextStore, paths string, source int, ignoreFunc shouldBeSkippedFunc) {
+func LoadAndWatchFiles(kubeConfigStore ContextStore, paths string, source int, ignoreFunc ShouldBeSkippedFunc) {
 	// create ticker
 	ticker := time.NewTicker(watchInterval)
 
@@ -106,7 +106,7 @@ func addFilesToWatcher(watcher *fsnotify.Watcher, paths []string) {
 }
 
 // syncContexts synchronizes the contexts in the store with the ones in the kubeconfig files.
-func syncContexts(kubeConfigStore ContextStore, paths string, source int, ignoreFunc shouldBeSkippedFunc) error {
+func syncContexts(kubeConfigStore ContextStore, paths string, source int, ignoreFunc ShouldBeSkippedFunc) error {
 	// First read all kubeconfig files to get new contexts
 	newContexts, _, err := LoadContextsFromMultipleFiles(paths, source)
 	if err != nil {