main.go

package main

import (
	"context"
	"database/sql"
	"fmt"
	"log"
	"net"
	"os"
	"time" // NEW IMPORT

	"cloud.google.com/go/cloudsqlconn"
	"contrib.go.opencensus.io/exporter/stackdriver" // NEW IMPORT
	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/stdlib"
	"go.opencensus.io/stats/view" // NEW IMPORT
)

func main() {
	var (
		dbUser                 = os.Getenv("DB_USER")
		dbPwd                  = os.Getenv("DB_PASS")
		dbName                 = os.Getenv("DB_NAME")
		instanceConnectionName = os.Getenv("INSTANCE_CONNECTION_NAME")
		usePrivate             = os.Getenv("PRIVATE_IP")
	)

	// ===================================================================
	// START: METRICS EXPORTER CONFIGURATION
	// ===================================================================

	// 1. Create the Stackdriver exporter
	exporter, err := stackdriver.NewExporter(stackdriver.Options{
		ProjectID: "jinphou-playground",
	})
	if err != nil {
		log.Fatalf("Failed to create Stackdriver exporter: %v", err)
	}
	defer exporter.Flush() // Flush exporter before the application exits

	// 2. Register the exporter with OpenCensus
	view.RegisterExporter(exporter)

	// 3. Set the reporting period
	view.SetReportingPeriod(60 * time.Second)

	// ===================================================================
	// END: METRICS EXPORTER CONFIGURATION
	// ===================================================================

	d, err := cloudsqlconn.NewDialer(context.Background())
	if err != nil {
		log.Fatalf("cloudsqlconn.NewDialer: %v", err)
	}
	// ... rest of the code is the same
	var opts []cloudsqlconn.DialOption
	if usePrivate != "" {
		opts = append(opts, cloudsqlconn.WithPrivateIP())
	}

	dsn := fmt.Sprintf("user=%s password=%s dbname=%s", dbUser, dbPwd, dbName)
	config, err := pgx.ParseConfig(dsn)
	if err != nil {
		log.Fatalf("pgx.ParseConfig: %v", err)
	}

	config.DialFunc = func(ctx context.Context, network, instance string) (net.Conn, error) {
		return d.Dial(ctx, instanceConnectionName, opts...)
	}

	db, err := sql.Open("pgx", stdlib.RegisterConnConfig(config))
	if err != nil {
		log.Fatalf("sql.Open: %v", err)
	}
	defer db.Close()

	log.Println("Pinging database...")
	err = db.PingContext(context.Background())
	if err != nil {
		log.Fatalf("failed to ping database: %v", err)
	}

	log.Println("Successfully connected to the database!")
	log.Println("Application is now running and exporting metrics...")

	select {}
}