app: backend: Add flag for watching plugins changes

This change creates a CLI flag in the backend + desktop for watching
changes to the plugins or their directory.

Stops watching for plugin changes in the container image.

Fixes: #2894

Signed-off-by: Evangelos Skopelitis <eskopelitis@microsoft.com>
Signed-off-by: René Dudfield <renedudfield@microsoft.com>

Dockerfile

@@ -95,4 +95,4 @@ USER headlamp
 EXPOSE 4466
 
 ENV HEADLAMP_STATIC_PLUGINS_DIR=/headlamp/static-plugins
-ENTRYPOINT ["/headlamp/headlamp-server", "-html-static-dir", "/headlamp/frontend", "-plugins-dir", "/headlamp/plugins"]
+ENTRYPOINT ["/headlamp/headlamp-server", "-html-static-dir", "/headlamp/frontend", "-plugins-dir", "/headlamp/plugins", "-watch-plugins-changes", "false"]

app/electron/main.ts

@@ -83,6 +83,10 @@ const args = yargs(hideBin(process.argv))
       describe: 'Disable use of GPU. For people who may have buggy graphics drivers',
       type: 'boolean',
     },
+    'watch-plugins-changes': {
+      describe: 'Reloads plugins when there are changes to them or their directory',
+      type: 'boolean',
+    },
   })
   .positional('kubeconfig', {
     describe:
@@ -551,6 +555,9 @@ async function startServer(flags: string[] = []): Promise<ChildProcessWithoutNul
   if (!!proxyUrls && proxyUrls.length > 0) {
     serverArgs = serverArgs.concat(['--proxy-urls', proxyUrls.join(',')]);
   }
+  if (args.watchPluginsChanges) {
+    serverArgs.push('--watch-plugins-changes');
+  }
 
   const bundledPlugins = path.join(process.resourcesPath, '.plugins');
 

backend/cmd/headlamp.go

@@ -47,6 +47,7 @@ type HeadlampConfig struct {
 	insecure              bool
 	enableHelm            bool
 	enableDynamicClusters bool
+	watchPluginsChanges   bool
 	port                  uint
 	kubeConfigPath        string
 	staticDir             string
@@ -355,7 +356,7 @@ func createHeadlampHandler(config *HeadlampConfig) http.Handler {
 
 	plugins.PopulatePluginsCache(config.staticPluginDir, config.pluginDir, config.cache)
 
-	if !config.useInCluster {
+	if !config.useInCluster && config.watchPluginsChanges {
 		// in-cluster mode is unlikely to want reloading plugins.
 		pluginEventChan := make(chan string)
 		go plugins.Watch(config.pluginDir, pluginEventChan)

backend/cmd/server.go

@@ -53,6 +53,7 @@ func main() {
 		proxyURLs:             strings.Split(conf.ProxyURLs, ","),
 		enableHelm:            conf.EnableHelm,
 		enableDynamicClusters: conf.EnableDynamicClusters,
+		watchPluginsChanges:   conf.WatchPluginsChanges,
 		cache:                 cache,
 		kubeConfigStore:       kubeConfigStore,
 		multiplexer:           multiplexer,

backend/pkg/config/config.go

@@ -26,6 +26,7 @@ type Config struct {
 	EnableHelm            bool   `koanf:"enable-helm"`
 	EnableDynamicClusters bool   `koanf:"enable-dynamic-clusters"`
 	ListenAddr            string `koanf:"listen-addr"`
+	WatchPluginsChanges   bool   `koanf:"watch-plugins-changes"`
 	Port                  uint   `koanf:"port"`
 	KubeConfigPath        string `koanf:"kubeconfig"`
 	StaticDir             string `koanf:"html-static-dir"`
@@ -154,6 +155,7 @@ func flagset() *flag.FlagSet {
 	f.Bool("dev", false, "Allow connections from other origins")
 	f.Bool("insecure-ssl", false, "Accept/Ignore all server SSL certificates")
 	f.Bool("enable-dynamic-clusters", false, "Enable dynamic clusters, which stores stateless clusters in the frontend.")
+	f.Bool("watch-plugins-changes", true, "Reloads plugins when there are changes to them or their directory")
 
 	f.String("kubeconfig", "", "Absolute path to the kubeconfig file")
 	f.String("html-static-dir", "", "Static HTML directory to serve")