Merge pull request #4228 from headlamp-k8s/open-browser

backend: embed: open Headlamp in default browser

Author: illume

backend/cmd/server.go

@@ -24,7 +24,9 @@ import (
 	"os"
 	"runtime"
 	"strings"
+	"time"
 
+	"github.com/cli/browser"
 	"github.com/gorilla/mux"
 	"github.com/kubernetes-sigs/headlamp/backend/pkg/cache"
 	"github.com/kubernetes-sigs/headlamp/backend/pkg/config"
@@ -33,6 +35,7 @@ import (
 	"github.com/kubernetes-sigs/headlamp/backend/pkg/kubeconfig"
 	"github.com/kubernetes-sigs/headlamp/backend/pkg/logger"
 	"github.com/kubernetes-sigs/headlamp/backend/pkg/plugins"
+	"github.com/kubernetes-sigs/headlamp/backend/pkg/spa"
 	"github.com/kubernetes-sigs/headlamp/backend/pkg/telemetry"
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/trace"
@@ -57,6 +60,17 @@ func main() {
 		return
 	}
 
+	// Open browser if running locally with embedded frontend and not in cluster and no-browser is not set
+	if spa.UseEmbeddedFiles && !conf.NoBrowser && !conf.InCluster {
+		go func() {
+			time.Sleep(500 * time.Millisecond) // give server time to start
+
+			if err := browser.OpenURL(fmt.Sprintf("http://localhost:%d", conf.Port)); err != nil {
+				logger.Log(logger.LevelError, nil, err, "failed to open browser")
+			}
+		}()
+	}
+
 	headlampConfig := createHeadlampConfig(conf)
 	StartHeadlampServer(headlampConfig)
 }

backend/go.mod

@@ -28,6 +28,7 @@ require (
 )
 
 require (
+	github.com/cli/browser v1.3.0
 	github.com/coreos/go-oidc/v3 v3.11.0
 	github.com/gorilla/websocket v1.5.4-0.20250319132907-e064f32e3674
 	github.com/jmespath/go-jmespath v0.4.0

backend/go.sum

@@ -64,6 +64,8 @@ github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UF
 github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
 github.com/chai2010/gettext-go v1.0.3 h1:9liNh8t+u26xl5ddmWLmsOsdNLwkdRTg5AG+JnTiM80=
 github.com/chai2010/gettext-go v1.0.3/go.mod h1:y+wnP2cHYaVj19NZhYKAwEMH2CI1gNHeQQ+5AjwawxA=
+github.com/cli/browser v1.3.0 h1:LejqCrpWr+1pRqmEPDGnTZOjsMe7sehifLynZJuqJpo=
+github.com/cli/browser v1.3.0/go.mod h1:HH8s+fOAxjhQoBUAsKuPCbqUuxZDhQ2/aD+SzsEfBTk=
 github.com/client9/misspell v0.3.4/go.mod h1:qj6jICC3Q7zFZvVWo7KLAzC3yx5G7kyvSDkc90ppPyw=
 github.com/cncf/udpa/go v0.0.0-20191209042840-269d4d468f6f/go.mod h1:M8M6+tZqaGXZJjfX53e64911xZQV5JYwmTeXPW+k8Sc=
 github.com/cncf/udpa/go v0.0.0-20201120205902-5459f2c99403/go.mod h1:WmhPx2Nbnhtbo57+VJT5O0JRkEi1Wbu0z5j0R8u5Hbk=

backend/pkg/config/config.go

@@ -16,6 +16,7 @@ import (
 	"github.com/knadh/koanf/providers/basicflag"
 	"github.com/knadh/koanf/providers/env"
 	"github.com/kubernetes-sigs/headlamp/backend/pkg/logger"
+	"github.com/kubernetes-sigs/headlamp/backend/pkg/spa"
 )
 
 const (
@@ -31,10 +32,14 @@ const (
 )
 
 type Config struct {
-	Version                   bool   `koanf:"version"`
-	InCluster                 bool   `koanf:"in-cluster"`
-	DevMode                   bool   `koanf:"dev"`
-	InsecureSsl               bool   `koanf:"insecure-ssl"`
+	Version     bool `koanf:"version"`
+	InCluster   bool `koanf:"in-cluster"`
+	DevMode     bool `koanf:"dev"`
+	InsecureSsl bool `koanf:"insecure-ssl"`
+	// NoBrowser disables automatically opening the default browser when running
+	// a locally embedded Headlamp binary (non in-cluster with spa.UseEmbeddedFiles == true).
+	// It has no effect in in-cluster mode or when running without embedded frontend.
+	NoBrowser                 bool   `koanf:"no-browser"`
 	CacheEnabled              bool   `koanf:"cache-enabled"`
 	EnableHelm                bool   `koanf:"enable-helm"`
 	EnableDynamicClusters     bool   `koanf:"enable-dynamic-clusters"`
@@ -320,7 +325,13 @@ func Parse(args []string) (*Config, error) {
 	setKubeConfigPath(&config)
 	setMeDefaults(&config)
 
-	// 8. Validate parsed config.
+	// 8. Validate flags that depend on build-time behaviour.
+	if err := validateOpenBrowser(&config, explicitFlags); err != nil {
+		logger.Log(logger.LevelError, nil, err, "validating open-browser flag")
+		return nil, err
+	}
+
+	// 9. Validate parsed config.
 	if err := config.Validate(); err != nil {
 		logger.Log(logger.LevelError, nil, err, "validating config")
 		return nil, err
@@ -369,6 +380,24 @@ func DefaultHeadlampKubeConfigFile() (string, error) {
 	return filepath.Join(kubeConfigDir, "config"), nil
 }
 
+// validateOpenBrowser ensures the open-browser option is only used when the
+// binary was built with embedded static files.
+func validateOpenBrowser(config *Config, explicitFlags map[string]bool) error {
+	// no-browser is only meaningful when running locally (non in-cluster) with
+	// an embedded frontend. Validate explicit usage accordingly.
+	if explicitFlags["no-browser"] {
+		if config.InCluster {
+			return errors.New("no-browser cannot be used in in-cluster mode")
+		}
+
+		if !spa.UseEmbeddedFiles {
+			return errors.New("no-browser cannot be used when running without embedded frontend")
+		}
+	}
+
+	return nil
+}
+
 func flagset() *flag.FlagSet {
 	f := flag.NewFlagSet("config", flag.ContinueOnError)
 
@@ -385,6 +414,7 @@ func addGeneralFlags(f *flag.FlagSet) {
 	f.Bool("in-cluster", false, "Set when running from a k8s cluster")
 	f.Bool("dev", false, "Allow connections from other origins")
 	f.Bool("cache-enabled", false, "K8s cache in backend")
+	f.Bool("no-browser", false, "Disable automatically opening the browser when using embedded frontend")
 	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.")
 	// Note: When running in-cluster and if not explicitly set, this flag defaults to false.

backend/pkg/config/config_test.go

@@ -159,6 +159,16 @@ func TestParseErrors(t *testing.T) {
 			args:          []string{"go run ./cmd", "--base-url=testingthis"},
 			errorContains: "base-url",
 		},
+		{
+			name:          "no_browser_without_embed",
+			args:          []string{"go run ./cmd", "--no-browser"},
+			errorContains: "no-browser cannot be used when running without embedded frontend",
+		},
+		{
+			name:          "no_browser_in_cluster",
+			args:          []string{"go run ./cmd", "--no-browser", "--in-cluster"},
+			errorContains: "no-browser cannot be used in in-cluster mode",
+		},
 	}
 
 	for _, tt := range tests {