feat(server): add graceful shutdown handling for SIGTERM and SIGINT

- Add signal handling for SIGTERM and SIGINT with context cancellation
- Implement cleanup function with detailed logging for shutdown events
- Log server startup and shutdown signals with version information
- Use context-aware StdioServer for graceful shutdown support
- Ensure database connections are properly closed on termination

This makes the server Docker/Kubernetes friendly and prevents connection leaks
during shutdown.

Implements #38

Author: sgaunet

main.go

@@ -9,6 +9,8 @@ import (
 	"log"
 	"log/slog"
 	"os"
+	"os/signal"
+	"syscall"
 
 	"github.com/mark3labs/mcp-go/mcp"
 	"github.com/mark3labs/mcp-go/server"
@@ -700,15 +702,38 @@ func main() {
 
 	registerAllTools(s, appInstance, debugLogger)
 
-	// Cleanup on exit
-	defer func() {
+	// Cleanup function
+	cleanup := func() {
+		debugLogger.Info("Starting cleanup...")
 		if err := appInstance.Disconnect(); err != nil {
 			debugLogger.Error("Failed to disconnect from database", "error", err)
+		} else {
+			debugLogger.Info("Database connection closed successfully")
 		}
+		debugLogger.Info("Server shutdown complete")
+	}
+	defer cleanup()
+
+	// Set up signal handling for graceful shutdown
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	sigChan := make(chan os.Signal, 1)
+	signal.Notify(sigChan, syscall.SIGTERM, syscall.SIGINT)
+
+	go func() {
+		sig := <-sigChan
+		debugLogger.Info("Received shutdown signal", "signal", sig.String())
+		cancel()
 	}()
 
 	// Start the stdio server
-	if err := server.ServeStdio(s); err != nil {
+	debugLogger.Info("Starting PostgreSQL MCP Server", "version", version)
+
+	// Create a custom StdioServer with context support
+	stdioServer := server.NewStdioServer(s)
+	if err := stdioServer.Listen(ctx, os.Stdin, os.Stdout); err != nil && err != context.Canceled {
+		debugLogger.Error("Server error", "error", err)
 		fmt.Fprintf(os.Stderr, "Server error: %v\n", err)
 		return
 	}