fix: thread stdout/stderr from cobra through to func-e for Host provider (#7142)

* fix: thread stdout/stderr from cobra through to func-e for Host provider

Fixes an issue where the Host infrastructure provider hardcoded `os.Stdout` when starting Envoy via func-e, bypassing output redirection configured through Cobra commands. This prevented applications like ai-gateway from properly capturing or redirecting Envoy's output when using the Host provider.

The fix threads stdout and stderr writers from Cobra's `cmd.OutOrStdout()` and `cmd.ErrOrStderr()` through the configuration chain to the `runEnvoy` function, which now uses func-e's three writer options: `api.Out()` for func-e status messages, `api.EnvoyOut()` for Envoy stdout, and `api.EnvoyErr()` for Envoy stderr.

Changes:
* Add Stdout and Stderr fields to config.Server struct
* Thread writers from server command through getConfig chain
* Add Stdout and Stderr fields to host.Infra struct
* Update runEnvoy to use i.Stdout/i.Stderr instead of hardcoded os.Stdout
* Add tests for output redirection behavior

Signed-off-by: Adrian Cole <[email protected]>

Author: codefromthecrypt

internal/cmd/certgen.go

@@ -61,7 +61,7 @@ func GetCertGenCommand() *cobra.Command {
 
 // certGen generates control plane certificates.
 func certGen(ctx context.Context, logOut io.Writer, local bool) error {
-	cfg, err := config.New(logOut)
+	cfg, err := config.New(logOut, io.Discard)
 	if err != nil {
 		return err
 	}

internal/cmd/certgen_test.go

@@ -21,6 +21,7 @@ import (
 	"sigs.k8s.io/controller-runtime/pkg/client/fake"
 
 	"github.com/envoyproxy/gateway/internal/crypto"
+	"github.com/envoyproxy/gateway/internal/envoygateway/config"
 )
 
 func TestGetCertgenCommand(t *testing.T) {
@@ -29,7 +30,7 @@ func TestGetCertgenCommand(t *testing.T) {
 }
 
 func TestOutputCertsForLocal(t *testing.T) {
-	cfg, err := getConfig(os.Stdout)
+	cfg, err := config.New(os.Stdout, os.Stderr)
 	require.NoError(t, err)
 
 	certs, err := crypto.GenerateCerts(cfg)
@@ -52,7 +53,7 @@ func TestOutputCertsForLocal(t *testing.T) {
 }
 
 func TestPatchTopologyWebhook(t *testing.T) {
-	cfg, err := getConfig(os.Stdout)
+	cfg, err := config.New(os.Stdout, os.Stderr)
 	require.NoError(t, err)
 
 	cases := []struct {

internal/cmd/server.go

@@ -45,7 +45,7 @@ func GetServerCommand() *cobra.Command {
 		Aliases: []string{"serve"},
 		Short:   "Serve Envoy Gateway",
 		RunE: func(cmd *cobra.Command, args []string) error {
-			return server(cmd.Context(), cmd.OutOrStdout())
+			return server(cmd.Context(), cmd.OutOrStdout(), cmd.ErrOrStderr())
 		},
 	}
 	cmd.PersistentFlags().StringVarP(&cfgPath, "config-path", "c", "",
@@ -55,8 +55,8 @@ func GetServerCommand() *cobra.Command {
 }
 
 // server serves Envoy Gateway.
-func server(ctx context.Context, logOut io.Writer) error {
-	cfg, err := getConfig(logOut)
+func server(ctx context.Context, stdout, stderr io.Writer) error {
+	cfg, err := getConfig(stdout, stderr)
 	if err != nil {
 		return err
 	}
@@ -72,7 +72,7 @@ func server(ctx context.Context, logOut io.Writer) error {
 		return nil
 	}
 	l := loader.New(cfgPath, cfg, hook)
-	if err := l.Start(ctx, logOut); err != nil {
+	if err := l.Start(ctx, stdout); err != nil {
 		return err
 	}
 
@@ -88,14 +88,14 @@ func server(ctx context.Context, logOut io.Writer) error {
 }
 
 // getConfig gets the Server configuration
-func getConfig(logOut io.Writer) (*config.Server, error) {
-	return getConfigByPath(logOut, cfgPath)
+func getConfig(stdout, stderr io.Writer) (*config.Server, error) {
+	return getConfigByPath(stdout, stderr, cfgPath)
 }
 
 // make `cfgPath` an argument to test it without polluting the global var
-func getConfigByPath(logOut io.Writer, cfgPath string) (*config.Server, error) {
+func getConfigByPath(stdout, stderr io.Writer, cfgPath string) (*config.Server, error) {
 	// Initialize with default config parameters.
-	cfg, err := config.New(logOut)
+	cfg, err := config.New(stdout, stderr)
 	if err != nil {
 		return nil, err
 	}
@@ -118,7 +118,7 @@ func getConfigByPath(logOut io.Writer, cfgPath string) (*config.Server, error) {
 		cfg.EnvoyGateway = eg
 		// update cfg logger
 		eg.Logging.SetEnvoyGatewayLoggingDefaults()
-		cfg.Logger = logging.NewLogger(logOut, eg.Logging)
+		cfg.Logger = logging.NewLogger(stdout, eg.Logging)
 	}
 
 	if err := cfg.Validate(); err != nil {

internal/cmd/server_test.go

@@ -6,6 +6,8 @@
 package cmd
 
 import (
+	"bytes"
+	"io"
 	"os"
 	"testing"
 
@@ -60,7 +62,7 @@ func TestGetConfigValidate(t *testing.T) {
 			_, err = file.WriteString(test.input)
 			require.NoError(t, err)
 
-			_, err = getConfigByPath(os.Stderr, file.Name())
+			_, err = getConfigByPath(io.Discard, io.Discard, file.Name())
 			if test.errors == nil {
 				require.NoError(t, err)
 			} else {
@@ -71,3 +73,26 @@ func TestGetConfigValidate(t *testing.T) {
 		})
 	}
 }
+
+// TestServerCommand_OutputRedirection verifies that the server command respects output redirection.
+func TestServerCommand_OutputRedirection(t *testing.T) {
+	file, err := os.CreateTemp("", "config")
+	require.NoError(t, err)
+	defer os.Remove(file.Name())
+
+	_, err = file.WriteString(validGatewayConfig)
+	require.NoError(t, err)
+
+	// Create separate buffers for stdout and stderr
+	stdout := &bytes.Buffer{}
+	stderr := &bytes.Buffer{}
+
+	// Test that getConfigByPath uses the provided writers
+	cfg, err := getConfigByPath(stdout, stderr, file.Name())
+	require.NoError(t, err)
+	require.NotNil(t, cfg)
+
+	// Verify the config has the writers set
+	require.Equal(t, stdout, cfg.Stdout)
+	require.Equal(t, stderr, cfg.Stderr)
+}

internal/crypto/certgen_test.go

@@ -26,7 +26,7 @@ func TestGenerateCerts(t *testing.T) {
 		wantEnvoyDNSName        string
 	}
 
-	cfg, err := config.New(os.Stdout)
+	cfg, err := config.New(os.Stdout, os.Stderr)
 	require.NoError(t, err)
 
 	run := func(t *testing.T, name string, tc testcase) {

internal/envoygateway/config/config.go

@@ -39,15 +39,21 @@ type Server struct {
 	Logger logging.Logger
 	// Elected chan is used to signal when an EG instance is elected as leader.
 	Elected chan struct{}
+	// Stdout is the writer for standard output.
+	Stdout io.Writer
+	// Stderr is the writer for error output.
+	Stderr io.Writer
 }
 
 // New returns a Server with default parameters.
-func New(logOut io.Writer) (*Server, error) {
+func New(stdout, stderr io.Writer) (*Server, error) {
 	return &Server{
 		EnvoyGateway:        egv1a1.DefaultEnvoyGateway(),
 		ControllerNamespace: env.Lookup("ENVOY_GATEWAY_NAMESPACE", DefaultNamespace),
 		DNSDomain:           env.Lookup("KUBERNETES_CLUSTER_DOMAIN", DefaultDNSDomain),
-		Logger:              logging.DefaultLogger(logOut, egv1a1.LogLevelInfo),
+		Logger:              logging.DefaultLogger(stdout, egv1a1.LogLevelInfo),
+		Stdout:              stdout,
+		Stderr:              stderr,
 		Elected:             make(chan struct{}),
 	}, nil
 }

internal/envoygateway/config/config_test.go

@@ -22,7 +22,7 @@ var (
 )
 
 func TestValidate(t *testing.T) {
-	cfg, err := New(os.Stdout)
+	cfg, err := New(os.Stdout, os.Stderr)
 	require.NoError(t, err)
 
 	testCases := []struct {

internal/envoygateway/config/loader/configloader_test.go

@@ -32,7 +32,7 @@ func TestConfigLoader(t *testing.T) {
 
 	cfgPath := tmpDir + "/config.yaml"
 	require.NoError(t, os.WriteFile(cfgPath, []byte(defaultConfig), 0o600))
-	s, err := config.New(os.Stdout)
+	s, err := config.New(os.Stdout, os.Stderr)
 	require.NoError(t, err)
 
 	ctx, cancel := context.WithCancel(context.TODO())

internal/gatewayapi/runner/runner_test.go

@@ -30,7 +30,7 @@ func TestRunner(t *testing.T) {
 	pResources := new(message.ProviderResources)
 	xdsIR := new(message.XdsIR)
 	infraIR := new(message.InfraIR)
-	cfg, err := config.New(os.Stdout)
+	cfg, err := config.New(os.Stdout, os.Stderr)
 	require.NoError(t, err)
 	extMgr, closeFunc, err := registry.NewInMemoryManager(&egv1a1.ExtensionManager{}, &pb.UnimplementedEnvoyGatewayExtensionServer{})
 	require.NoError(t, err)
@@ -70,7 +70,7 @@ func setupTestRunner(t *testing.T) (*Runner, []types.NamespacedName) {
 	pResources := new(message.ProviderResources)
 	xdsIR := new(message.XdsIR)
 	infraIR := new(message.InfraIR)
-	cfg, err := config.New(os.Stdout)
+	cfg, err := config.New(os.Stdout, os.Stderr)
 	require.NoError(t, err)
 	extMgr, closeFunc, err := registry.NewInMemoryManager(&egv1a1.ExtensionManager{}, &pb.UnimplementedEnvoyGatewayExtensionServer{})
 	require.NoError(t, err)

internal/globalratelimit/runner/runner_test.go

@@ -210,7 +210,7 @@ func Test_subscribeAndTranslate(t *testing.T) {
 			defer cancel()
 			xdsIR := new(message.XdsIR)
 			defer xdsIR.Close()
-			cfg, err := config.New(os.Stdout)
+			cfg, err := config.New(os.Stdout, os.Stderr)
 			require.NoError(t, err)
 
 			r := New(&Config{