connect_connector.go

// Copyright 2022 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// [START cloud_sql_postgres_databasesql_connect_connector]
package cloudsql

import (
	"context"
	"database/sql"
	"fmt"
	"log"
	"net"
	"os"

	"cloud.google.com/go/cloudsqlconn"
	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/stdlib"
)

func connectWithConnector() (*sql.DB, error) {
	mustGetenv := func(k string) string {
		v := os.Getenv(k)
		if v == "" {
			log.Fatalf("Fatal Error in connect_connector.go: %s environment variable not set.\n", k)
		}
		return v
	}
	// Note: Saving credentials in environment variables is convenient, but not
	// secure - consider a more secure solution such as
	// Cloud Secret Manager (https://cloud.google.com/secret-manager) to help
	// keep passwords and other secrets safe.
	var (
		dbUser                 = mustGetenv("DB_USER")                  // e.g. 'my-db-user'
		dbPwd                  = mustGetenv("DB_PASS")                  // e.g. 'my-db-password'
		dbName                 = mustGetenv("DB_NAME")                  // e.g. 'my-database'
		instanceConnectionName = mustGetenv("INSTANCE_CONNECTION_NAME") // e.g. 'project:region:instance'
		usePrivate             = os.Getenv("PRIVATE_IP")
	)

	dsn := fmt.Sprintf("user=%s password=%s database=%s", dbUser, dbPwd, dbName)
	config, err := pgx.ParseConfig(dsn)
	if err != nil {
		return nil, err
	}
	var opts []cloudsqlconn.Option
	if usePrivate != "" {
		opts = append(opts, cloudsqlconn.WithDefaultDialOptions(cloudsqlconn.WithPrivateIP()))
	}
	// WithLazyRefresh() Option is used to perform refresh
	// when needed, rather than on a scheduled interval.
	// This is recommended for serverless environments to
	// avoid background refreshes from throttling CPU.
	opts = append(opts, cloudsqlconn.WithLazyRefresh())
	d, err := cloudsqlconn.NewDialer(context.Background(), opts...)
	if err != nil {
		return nil, err
	}
	// Use the Cloud SQL connector to handle connecting to the instance.
	// This approach does *NOT* require the Cloud SQL proxy.
	config.DialFunc = func(ctx context.Context, network, instance string) (net.Conn, error) {
		return d.Dial(ctx, instanceConnectionName)
	}
	dbURI := stdlib.RegisterConnConfig(config)
	dbPool, err := sql.Open("pgx", dbURI)
	if err != nil {
		return nil, fmt.Errorf("sql.Open: %w", err)
	}
	return dbPool, nil
}

// [END cloud_sql_postgres_databasesql_connect_connector]