feat: always remove stale unix sockets (#2)

Signed-off-by: Leonardo Cecchi <[email protected]>

go.mod

@@ -10,6 +10,7 @@ require (
 	github.com/evanphx/json-patch/v5 v5.8.1
 	github.com/go-logr/logr v1.3.0
 	github.com/go-logr/zapr v1.2.4
+	github.com/grpc-ecosystem/go-grpc-middleware/v2 v2.0.1
 	github.com/spf13/cobra v1.8.0
 	github.com/spf13/viper v1.14.0
 	go.uber.org/zap v1.26.0

go.sum

@@ -170,6 +170,8 @@ github.com/googleapis/gax-go/v2 v2.0.4/go.mod h1:0Wqv26UfaUD9n4G6kQubkQ+KchISgw+
 github.com/googleapis/gax-go/v2 v2.0.5/go.mod h1:DWXyrwAJ9X0FpwwEdw+IPEYBICEFu5mhpdKc/us6bOk=
 github.com/googleapis/google-cloud-go-testing v0.0.0-20200911160855-bcd43fbb19e8/go.mod h1:dvDLG8qkwmyD9a/MJJN3XJcT3xFxOKAvTZGvuZmac9g=
 github.com/gorilla/websocket v1.4.2/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
+github.com/grpc-ecosystem/go-grpc-middleware/v2 v2.0.1 h1:HcUWd006luQPljE73d5sk+/VgYPGUReEVz2y1/qylwY=
+github.com/grpc-ecosystem/go-grpc-middleware/v2 v2.0.1/go.mod h1:w9Y7gY31krpLmrVU5ZPG9H7l9fZuRu5/3R3S3FMtVQ4=
 github.com/hashicorp/golang-lru v0.5.0/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
 github.com/hashicorp/golang-lru v0.5.1/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
 github.com/hashicorp/hcl v1.0.0 h1:0Anlzjpi4vEasTeNFn2mLJgTSwt0+6sfsiTG8qcWGx4=
@@ -272,8 +274,8 @@ github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/
 github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
 github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
-github.com/stretchr/testify v1.8.2 h1:+h33VjcLVPDHtOdpUCuF+7gSuG3yGIftsP1YvFihtJ8=
-github.com/stretchr/testify v1.8.2/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
+github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
+github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
 github.com/subosito/gotenv v1.4.1 h1:jyEFiXpy21Wm81FBN71l9VoMMV8H8jG+qIK3GCpY6Qs=
 github.com/subosito/gotenv v1.4.1/go.mod h1:ayKnFf/c6rvx/2iiLrJUk1e6plDbT3edrFNGqEflhK0=
 github.com/yuin/goldmark v1.1.25/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=

pkg/pluginhelper/server.go

@@ -1,10 +1,16 @@
 package pluginhelper
 
 import (
+	"context"
+	"errors"
 	"net"
+	"os"
+	"os/signal"
 	"path"
+	"syscall"
 
 	"github.com/cloudnative-pg/cnpg-i/pkg/identity"
+	"github.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors/recovery"
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
 	"google.golang.org/grpc"
@@ -31,53 +37,7 @@ func CreateMainCmd(identityImpl identity.IdentityServer, enrichers ...ServerEnri
 		},
 		Args: cobra.NoArgs,
 		RunE: func(cmd *cobra.Command, _ []string) error {
-			logger := logging.FromContext(cmd.Context())
-
-			identityResponse, err := identityImpl.GetPluginMetadata(
-				cmd.Context(),
-				&identity.GetPluginMetadataRequest{})
-			if err != nil {
-				logger.Error(err, "Error while querying the identity service")
-				return err
-			}
-
-			pluginPath := viper.GetString("plugin-path")
-			pluginName := identityResponse.Name
-			pluginDisplayName := identityResponse.DisplayName
-			pluginVersion := identityResponse.Version
-			socketName := path.Join(pluginPath, identityResponse.Name)
-
-			grpcServer := grpc.NewServer()
-			identity.RegisterIdentityServer(
-				grpcServer,
-				identityImpl)
-			for _, enrich := range enrichers {
-				enrich(grpcServer)
-			}
-
-			listener, err := net.Listen(
-				unixNetwork,
-				socketName,
-			)
-			if err != nil {
-				logger.Error(err, "While starting server")
-				return err
-			}
-
-			logger.Info(
-				"Starting plugin",
-				"path", pluginPath,
-				"name", pluginName,
-				"displayName", pluginDisplayName,
-				"version", pluginVersion,
-				"socketName", socketName,
-			)
-			err = grpcServer.Serve(listener)
-			if err != nil {
-				logger.Error(err, "While terminatind server")
-			}
-
-			return err
+			return run(cmd.Context(), identityImpl, enrichers...)
 		},
 	}
 
@@ -97,3 +57,125 @@ func CreateMainCmd(identityImpl identity.IdentityServer, enrichers ...ServerEnri
 
 	return cmd
 }
+
+// run starts listining for GRPC requests
+func run(ctx context.Context, identityImpl identity.IdentityServer, enrichers ...ServerEnricher) error {
+	logger := logging.FromContext(ctx)
+
+	identityResponse, err := identityImpl.GetPluginMetadata(
+		ctx,
+		&identity.GetPluginMetadataRequest{})
+	if err != nil {
+		logger.Error(err, "Error while querying the identity service")
+		return err
+	}
+
+	pluginPath := viper.GetString("plugin-path")
+	pluginName := identityResponse.Name
+	pluginDisplayName := identityResponse.DisplayName
+	pluginVersion := identityResponse.Version
+	socketName := path.Join(pluginPath, identityResponse.Name)
+
+	// Remove stale unix socket it still existent
+	if err := removeStaleSocket(ctx, socketName); err != nil {
+		logger.Error(err, "While removing old unix socket")
+		return err
+	}
+
+	// Start accepting connections on the socket
+	listener, err := net.Listen(
+		unixNetwork,
+		socketName,
+	)
+	if err != nil {
+		logger.Error(err, "While starting server")
+		return err
+	}
+
+	// Handle quit-like signal
+	handleSignals(ctx, listener)
+
+	// Create GRPC server
+	grpcServer := grpc.NewServer(
+		grpc.ChainUnaryInterceptor(
+			recovery.UnaryServerInterceptor(recovery.WithRecoveryHandlerContext(panicRecoveryHandler(listener))),
+		),
+		grpc.ChainStreamInterceptor(
+			recovery.StreamServerInterceptor(recovery.WithRecoveryHandlerContext(panicRecoveryHandler(listener))),
+		),
+	)
+	identity.RegisterIdentityServer(
+		grpcServer,
+		identityImpl)
+	for _, enrich := range enrichers {
+		enrich(grpcServer)
+	}
+
+	logger.Info(
+		"Starting plugin",
+		"path", pluginPath,
+		"name", pluginName,
+		"displayName", pluginDisplayName,
+		"version", pluginVersion,
+		"socketName", socketName,
+	)
+
+	if err = grpcServer.Serve(listener); !errors.Is(err, net.ErrClosed) {
+		logger.Error(err, "While terminating server")
+	}
+
+	return nil
+}
+
+// removeStaleSocket removes a stale unix domain socket
+func removeStaleSocket(ctx context.Context, pluginPath string) error {
+	logger := logging.FromContext(ctx)
+	_, err := os.Stat(pluginPath)
+
+	switch {
+	case err == nil:
+		logger.Info("Removing stale socket", "pluginPath", pluginPath)
+		return os.Remove(pluginPath)
+
+	case errors.Is(err, os.ErrNotExist):
+		return nil
+
+	default:
+		return err
+	}
+}
+
+// handleSignals makes sure that we close the listening socket
+// when we receive a quit-like signal
+func handleSignals(ctx context.Context, listener net.Listener) {
+	logger := logging.FromContext(ctx)
+
+	sigc := make(chan os.Signal, 1)
+	signal.Notify(sigc, syscall.SIGTERM, syscall.SIGABRT, syscall.SIGINT)
+	go func(c chan os.Signal) {
+		sig := <-c
+		logger.Info(
+			"Caught signal, shutting down.",
+			"signal", sig.String())
+
+		if err := listener.Close(); err != nil {
+			logger.Error(err, "While stopping server")
+		}
+
+		os.Exit(1)
+	}(sigc)
+}
+
+func panicRecoveryHandler(listener net.Listener) recovery.RecoveryHandlerFuncContext {
+	return func(ctx context.Context, err any) error {
+		logger := logging.FromContext(ctx)
+		logger.Info("Panic occurred", "error", err)
+
+		if closeError := listener.Close(); closeError != nil {
+			logger.Error(closeError, "While stopping server")
+		}
+
+		os.Exit(1)
+		return nil
+	}
+}