Create a connection using the Cloud SQL Go Connector

Open a connection to Cloud SQL for SQL Server by using the Cloud SQL Go Connector.

Explore further

For detailed documentation that includes this code sample, see the following:

Code sample


To authenticate to Cloud SQL for SQL Server, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

package cloudsql

import (

	mssql ""

type csqlDialer struct {
	dialer     *cloudsqlconn.Dialer
	connName   string
	usePrivate bool

// DialContext adheres to the mssql.Dialer interface.
func (c *csqlDialer) DialContext(ctx context.Context, network, addr string) (net.Conn, error) {
	var opts []cloudsqlconn.DialOption
	if c.usePrivate {
		opts = append(opts, cloudsqlconn.WithPrivateIP())
	return c.dialer.Dial(ctx, c.connName, opts...)

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 ( to help
	// keep 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")

	dbURI := fmt.Sprintf("user id=%s;password=%s;database=%s;", dbUser, dbPwd, dbName)
	c, err := mssql.NewConnector(dbURI)
	if err != nil {
		return nil, fmt.Errorf("mssql.NewConnector: %w", err)
	dialer, err := cloudsqlconn.NewDialer(context.Background())
	if err != nil {
		return nil, fmt.Errorf("cloudsqlconn.NewDailer: %w", err)
	c.Dialer = &csqlDialer{
		dialer:     dialer,
		connName:   instanceConnectionName,
		usePrivate: usePrivate != "",

	dbPool := sql.OpenDB(c)
	if err != nil {
		return nil, fmt.Errorf("sql.Open: %w", err)
	return dbPool, nil

What's next

To search and filter code samples for other Google Cloud products, see the Google Cloud sample browser.