Connect from App Engine flexible environment

MySQL   |  PostgreSQL   |  SQL Server

This page contains information and examples for connecting to a Cloud SQL instance from a service running in App Engine flexible environment.

Cloud SQL is a fully-managed database service that helps you set up, maintain, manage, and administer your relational databases in the cloud.

App Engine is a fully managed, serverless platform for developing and hosting web applications at scale. You can choose from several popular languages, libraries, and frameworks to develop your apps, then let App Engine take care of provisioning servers and scaling your app instances based on demand.

Set up a Cloud SQL instance

1. Enable the Cloud SQL Admin API in the Google Cloud project that you are connecting from, if you haven't already done so:

   Enable the API

2. Create a Cloud SQL for MySQL instance. We recommend that you choose a Cloud SQL instance location in the same region as your Cloud Run service for better latency, to avoid some networking costs, and to reduce cross region failure risks.

   By default, Cloud SQL assigns a public IP address to a new instance. You also have the option to assign a private IP address. For more information about the connectivity options for both, see the Connecting Overview page.

Configure App Engine flexible environment

The steps to configure App Engine flexible environment depend on the type of IP address that you assigned to your Cloud SQL instance.

Public IP (default)

To configure App Engine flexible environment to enable connections to a Cloud SQL instance:

1. Make sure that the instance has a public IP address. You can verify this on the Overview page for your instance in the Google Cloud console. If you need to add one, see the Configuring public IP page for instructions.
2. Get the INSTANCE_CONNECTION_NAME for your instance. You can find this value on the Overview page for your instance in the Google Cloud console or by running the following gcloud sql instances describe command:

   gcloud sql instances describe INSTANCE_NAME
      

   Replace INSTANCE_NAME with the name of your Cloud SQL instance.
3. Ensure that the service account your app is using to authenticate calls to Cloud SQL has the appropriate Cloud SQL roles and permissions.
   • The service account for your service needs one of the following IAM roles:
     • Cloud SQL Client (preferred)
     • Cloud SQL Editor
     • Cloud SQL Admin
     Or, you can manually assign both of the following IAM permissions:
     • cloudsql.instances.connect
     • cloudsql.instances.get
     For detailed instructions on adding IAM roles to a service account, see Granting Roles to Service Accounts.

   By default, your app will authorize your connections using the App Engine flexible environment service account. The service account is in the format [e-mail].

   If the authorizing service account belongs to a different project than the Cloud SQL instance, the Cloud SQL Admin API and IAM permissions will need to be added for both projects.

4. Update your project's app.yaml file with the option that works best. You can use a comma-separated list of instances to specify multiple options at once.

   Enabling a Unix domain socket

   To enable a Unix domain socket, add one of the following to your project's app.yaml file, depending on whether you are connecting to one or multiple instances:

   beta_settings:
     cloud_sql_instances: INSTANCE_CONNECTION_NAME

   beta_settings:
     cloud_sql_instances: INSTANCE_CONNECTION_NAME,INSTANCE_CONNECTION_NAME_2,...

   Enabling a TCP Port

   To enable a local TCP port, add one of the following to your project's app.yaml file, depending on whether you are connecting to one or multiple instances:

   beta_settings:
     cloud_sql_instances: INSTANCE_CONNECTION_NAME=tcp:PORT

   beta_settings:
     cloud_sql_instances: INSTANCE_CONNECTION_NAME_1=tcp:PORT_1,INSTANCE_CONNECTION_NAME_2=tcp:PORT_2,...

Private IP

In order to connect to your Cloud SQL instance over private IP, your App Engine flexible environment deployment must be in the same VPC network as your Cloud SQL instance. See the configuration documentation on Network Settings for instructions on how to specify a VPC network for your deployment.

Once deployed, your application will be able to connect directly using your instance's private IP address and port 3306.

Connect to Cloud SQL

After you configure App Engine flexible environment, you can connect to your Cloud SQL instance.

Public IP (default)

For public IP paths, App Engine flexible environment provides encryption and connects using the Cloud SQL Auth Proxy in three ways:

• Through TCP sockets
• Through Unix sockets
• By using a Cloud SQL connector

Connect with TCP

Connect directly using the 172.17.0.1:PORT where PORT is the port you specified in the app.yaml file. The Cloud SQL Auth Proxy is listening on 172.17.0.1 and will encrypt and forward the connection to the Cloud SQL instance.

Python

To see this snippet in the context of a web application, view the README on GitHub.

import os

import sqlalchemy


def connect_tcp_socket() -> sqlalchemy.engine.base.Engine:
    """Initializes a TCP connection pool for a Cloud SQL instance of MySQL."""
    # 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 secrets safe.
    db_host = os.environ[
        "INSTANCE_HOST"
    ]  # e.g. '127.0.0.1' ('172.17.0.1' if deployed to GAE Flex)
    db_user = os.environ["DB_USER"]  # e.g. 'my-db-user'
    db_pass = os.environ["DB_PASS"]  # e.g. 'my-db-password'
    db_name = os.environ["DB_NAME"]  # e.g. 'my-database'
    db_port = os.environ["DB_PORT"]  # e.g. 3306

    pool = sqlalchemy.create_engine(
        # Equivalent URL:
        # mysql+pymysql://<db_user>:<db_pass>@<db_host>:<db_port>/<db_name>
        sqlalchemy.engine.url.URL.create(
            drivername="mysql+pymysql",
            username=db_user,
            password=db_pass,
            host=db_host,
            port=db_port,
            database=db_name,
        ),
        # ...
    )
    return pool

Java

To see this snippet in the context of a web application, view the README on GitHub.

Note:

• INSTANCE_CONNECTION_NAME should be represented as <MY-PROJECT>:<INSTANCE-REGION>:<INSTANCE-NAME>
• Using the argument ipTypes=PRIVATE will force the SocketFactory to connect with an instance's associated private IP
• See the JDBC socket factory version requirements for the pom.xml file here .

import com.zaxxer.hikari.HikariConfig;
import com.zaxxer.hikari.HikariDataSource;
import javax.sql.DataSource;

public class TcpConnectionPoolFactory extends ConnectionPoolFactory {

  // Saving credentials in environment variables is convenient, but not secure - consider a more
  // secure solution such as https://cloud.google.com/secret-manager/ to help keep secrets safe.
  private static final String DB_USER = System.getenv("DB_USER");
  private static final String DB_PASS = System.getenv("DB_PASS");
  private static final String DB_NAME = System.getenv("DB_NAME");

  private static final String INSTANCE_HOST = System.getenv("INSTANCE_HOST");
  private static final String DB_PORT = System.getenv("DB_PORT");


  public static DataSource createConnectionPool() {
    // The configuration object specifies behaviors for the connection pool.
    HikariConfig config = new HikariConfig();

    // The following URL is equivalent to setting the config options below:
    // jdbc:mysql://<INSTANCE_HOST>:<DB_PORT>/<DB_NAME>?user=<DB_USER>&password=<DB_PASS>
    // See the link below for more info on building a JDBC URL for the Cloud SQL JDBC Socket Factory
    // https://github.com/GoogleCloudPlatform/cloud-sql-jdbc-socket-factory#creating-the-jdbc-url

    // Configure which instance and what database user to connect with.
    config.setJdbcUrl(String.format("jdbc:mysql://%s:%s/%s", INSTANCE_HOST, DB_PORT, DB_NAME));
    config.setUsername(DB_USER); // e.g. "root", "mysql"
    config.setPassword(DB_PASS); // e.g. "my-password"


    // ... Specify additional connection properties here.
    // ...

    // Initialize the connection pool using the configuration object.
    return new HikariDataSource(config);
  }
}

Node.js

To see this snippet in the context of a web application, view the README on GitHub.

const mysql = require('promise-mysql');
const fs = require('fs');

// createTcpPool initializes a TCP connection pool for a Cloud SQL
// instance of MySQL.
const createTcpPool = async config => {
  // 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 secrets safe.
  const dbConfig = {
    host: process.env.INSTANCE_HOST, // e.g. '127.0.0.1'
    port: process.env.DB_PORT, // e.g. '3306'
    user: process.env.DB_USER, // e.g. 'my-db-user'
    password: process.env.DB_PASS, // e.g. 'my-db-password'
    database: process.env.DB_NAME, // e.g. 'my-database'
    // ... Specify additional properties here.
    ...config,
  };
  // Establish a connection to the database.
  return mysql.createPool(dbConfig);
};

Go

To see this snippet in the context of a web application, view the README on GitHub.

package cloudsql

import (
	"crypto/tls"
	"crypto/x509"
	"database/sql"
	"errors"
	"fmt"
	"log"
	"os"

	"github.com/go-sql-driver/mysql"
)

// connectTCPSocket initializes a TCP connection pool for a Cloud SQL
// instance of MySQL.
func connectTCPSocket() (*sql.DB, error) {
	mustGetenv := func(k string) string {
		v := os.Getenv(k)
		if v == "" {
			log.Fatalf("Fatal Error in connect_tcp.go: %s environment variable not set.", 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 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'
		dbPort    = mustGetenv("DB_PORT")       // e.g. '3306'
		dbTCPHost = mustGetenv("INSTANCE_HOST") // e.g. '127.0.0.1' ('172.17.0.1' if deployed to GAE Flex)
	)

	dbURI := fmt.Sprintf("%s:%s@tcp(%s:%s)/%s?parseTime=true",
		dbUser, dbPwd, dbTCPHost, dbPort, dbName)


	// dbPool is the pool of database connections.
	dbPool, err := sql.Open("mysql", dbURI)
	if err != nil {
		return nil, fmt.Errorf("sql.Open: %w", err)
	}

	// ...

	return dbPool, nil
}

C#

To see this snippet in the context of a web application, view the README on GitHub.

using MySql.Data.MySqlClient;
using System;

namespace CloudSql
{
    public class MySqlTcp
    {
        public static MySqlConnectionStringBuilder NewMysqlTCPConnectionString()
        {
            // Equivalent connection string:
            // "Uid=<DB_USER>;Pwd=<DB_PASS>;Host=<INSTANCE_HOST>;Database=<DB_NAME>;"
            var connectionString = new MySqlConnectionStringBuilder()
            {
                // 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 secrets safe.
                Server = Environment.GetEnvironmentVariable("INSTANCE_HOST"),   // e.g. '127.0.0.1'
                // Set Host to 'cloudsql' when deploying to App Engine Flexible environment
                UserID = Environment.GetEnvironmentVariable("DB_USER"),   // e.g. 'my-db-user'
                Password = Environment.GetEnvironmentVariable("DB_PASS"), // e.g. 'my-db-password'
                Database = Environment.GetEnvironmentVariable("DB_NAME"), // e.g. 'my-database'

                // The Cloud SQL proxy provides encryption between the proxy and instance.
                SslMode = MySqlSslMode.Disabled,
            };
            connectionString.Pooling = true;
            // Specify additional properties here.
            return connectionString;

        }
    }
}

Ruby

To see this snippet in the context of a web application, view the README on GitHub.

tcp: &tcp
  adapter: mysql2
  # Configure additional properties here
  # 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 secrets safe.
  username: <%= ENV["DB_USER"] %>  # e.g. "my-database-user"
  password: <%= ENV["DB_PASS"] %> # e.g. "my-database-password"
  database: <%= ENV.fetch("DB_NAME") { "vote_development" } %>
  host: "<%= ENV.fetch("INSTANCE_HOST") { "127.0.0.1" }%>" # '172.17.0.1' if deployed to GAE Flex
  port: <%= ENV.fetch("DB_PORT") { 3306 }%>

PHP

To see this snippet in the context of a web application, view the README on GitHub.

namespace Google\Cloud\Samples\CloudSQL\MySQL;

use PDO;
use PDOException;
use RuntimeException;
use TypeError;

class DatabaseTcp
{
    public static function initTcpDatabaseConnection(): PDO
    {
        try {
            // 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 secrets safe.
            $username = getenv('DB_USER'); // e.g. 'your_db_user'
            $password = getenv('DB_PASS'); // e.g. 'your_db_password'
            $dbName = getenv('DB_NAME'); // e.g. 'your_db_name'
            $instanceHost = getenv('INSTANCE_HOST'); // e.g. '127.0.0.1' ('172.17.0.1' for GAE Flex)

            // Connect using TCP
            $dsn = sprintf('mysql:dbname=%s;host=%s', $dbName, $instanceHost);

            // Connect to the database
            $conn = new PDO(
                $dsn,
                $username,
                $password,
                # ...
            );
        } catch (TypeError $e) {
            throw new RuntimeException(
                sprintf(
                    'Invalid or missing configuration! Make sure you have set ' .
                        '$username, $password, $dbName, and $instanceHost (for TCP mode). ' .
                        'The PHP error was %s',
                    $e->getMessage()
                ),
                $e->getCode(),
                $e
            );
        } catch (PDOException $e) {
            throw new RuntimeException(
                sprintf(
                    'Could not connect to the Cloud SQL Database. Check that ' .
                        'your username and password are correct, that the Cloud SQL ' .
                        'proxy is running, and that the database exists and is ready ' .
                        'for use. For more assistance, refer to %s. The PDO error was %s',
                    'https://cloud.google.com/sql/docs/mysql/connect-external-app',
                    $e->getMessage()
                ),
                $e->getCode(),
                $e
            );
        }

        return $conn;
    }
}

Connect with Unix sockets

Once correctly configured, you can connect your service to your Cloud SQL instance's Unix domain socket accessed on the environment's filesystem at the following path: /cloudsql/INSTANCE_CONNECTION_NAME.

The INSTANCE_CONNECTION_NAME uses the format project:region:instance-id. You can find it on the Overview page for your instance in the Google Cloud console or by running the following command:

gcloud sql instances describe [INSTANCE_NAME]

These connections are automatically encrypted without any additional configuration.

The code samples shown below are extracts from more complete examples on the GitHub site. Click View on GitHub to see more.

Warning: Linux-based operating systems have a maximum socket path length of 108 characters. If the total length of the path exceeds this length, you cannot connect with a socket from App Engine flexible environment.

Python

To see this snippet in the context of a web application, view the README on GitHub.

import os

import sqlalchemy


def connect_unix_socket() -> sqlalchemy.engine.base.Engine:
    """Initializes a Unix socket connection pool for a Cloud SQL instance of MySQL."""
    # 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 secrets safe.
    db_user = os.environ["DB_USER"]  # e.g. 'my-database-user'
    db_pass = os.environ["DB_PASS"]  # e.g. 'my-database-password'
    db_name = os.environ["DB_NAME"]  # e.g. 'my-database'
    unix_socket_path = os.environ[
        "INSTANCE_UNIX_SOCKET"
    ]  # e.g. '/cloudsql/project:region:instance'

    pool = sqlalchemy.create_engine(
        # Equivalent URL:
        # mysql+pymysql://<db_user>:<db_pass>@/<db_name>?unix_socket=<socket_path>/<cloud_sql_instance_name>
        sqlalchemy.engine.url.URL.create(
            drivername="mysql+pymysql",
            username=db_user,
            password=db_pass,
            database=db_name,
            query={"unix_socket": unix_socket_path},
        ),
        # ...
    )
    return pool

Java

To see this snippet in the context of a web application, view the README on GitHub.

import com.zaxxer.hikari.HikariConfig;
import com.zaxxer.hikari.HikariDataSource;
import javax.sql.DataSource;

public class ConnectorConnectionPoolFactory extends ConnectionPoolFactory {

  // 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 secrets safe.
  private static final String INSTANCE_CONNECTION_NAME =
      System.getenv("INSTANCE_CONNECTION_NAME");
  private static final String INSTANCE_UNIX_SOCKET = System.getenv("INSTANCE_UNIX_SOCKET");
  private static final String DB_USER = System.getenv("DB_USER");
  private static final String DB_PASS = System.getenv("DB_PASS");
  private static final String DB_NAME = System.getenv("DB_NAME");

  public static DataSource createConnectionPool() {
    // The configuration object specifies behaviors for the connection pool.
    HikariConfig config = new HikariConfig();

    // The following URL is equivalent to setting the config options below:
    // jdbc:mysql:///<DB_NAME>?cloudSqlInstance=<INSTANCE_CONNECTION_NAME>&
    // socketFactory=com.google.cloud.sql.mysql.SocketFactory&user=<DB_USER>&password=<DB_PASS>
    // See the link below for more info on building a JDBC URL for the Cloud SQL JDBC Socket Factory
    // https://github.com/GoogleCloudPlatform/cloud-sql-jdbc-socket-factory#creating-the-jdbc-url

    // Configure which instance and what database user to connect with.
    config.setJdbcUrl(String.format("jdbc:mysql:///%s", DB_NAME));
    config.setUsername(DB_USER); // e.g. "root", "mysql"
    config.setPassword(DB_PASS); // e.g. "my-password"

    config.addDataSourceProperty("socketFactory", "com.google.cloud.sql.mysql.SocketFactory");
    config.addDataSourceProperty("cloudSqlInstance", INSTANCE_CONNECTION_NAME);

    // Unix sockets are not natively supported in Java, so it is necessary to use the Cloud SQL
    // Java Connector to connect. When setting INSTANCE_UNIX_SOCKET, the connector will 
    // call an external package that will enable Unix socket connections.
    // Note: For Java users, the Cloud SQL Java Connector can provide authenticated connections
    // which is usually preferable to using the Cloud SQL Proxy with Unix sockets.
    // See https://github.com/GoogleCloudPlatform/cloud-sql-jdbc-socket-factory for details.
    if (INSTANCE_UNIX_SOCKET != null) {
      config.addDataSourceProperty("unixSocketPath", INSTANCE_UNIX_SOCKET);
    }


    // ... Specify additional connection properties here.
    // ...

    // Initialize the connection pool using the configuration object.
    return new HikariDataSource(config);
  }
}

Node.js

To see this snippet in the context of a web application, view the README on GitHub.

const mysql = require('promise-mysql');

// createUnixSocketPool initializes a Unix socket connection pool for
// a Cloud SQL instance of MySQL.
const createUnixSocketPool = async config => {
  // 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 secrets safe.
  return mysql.createPool({
    user: process.env.DB_USER, // e.g. 'my-db-user'
    password: process.env.DB_PASS, // e.g. 'my-db-password'
    database: process.env.DB_NAME, // e.g. 'my-database'
    socketPath: process.env.INSTANCE_UNIX_SOCKET, // e.g. '/cloudsql/project:region:instance'
    // Specify additional properties here.
    ...config,
  });
};

C#

To see this snippet in the context of a web application, view the README on GitHub.

using MySql.Data.MySqlClient;
using System;

namespace CloudSql
{
    public class MySqlUnix
    {
        public static MySqlConnectionStringBuilder NewMysqlUnixSocketConnectionString()
        {
            // Equivalent connection string:
            // "Server=<INSTANCE_UNIX_SOCKET>;Uid=<DB_USER>;Pwd=<DB_PASS>;Database=<DB_NAME>;Protocol=unix"
            var connectionString = new MySqlConnectionStringBuilder()
            {
                // The Cloud SQL proxy provides encryption between the proxy and instance.
                SslMode = MySqlSslMode.Disabled,

                // 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 secrets safe.
                Server = Environment.GetEnvironmentVariable("INSTANCE_UNIX_SOCKET"), // e.g. '/cloudsql/project:region:instance'
                UserID = Environment.GetEnvironmentVariable("DB_USER"),   // e.g. 'my-db-user
                Password = Environment.GetEnvironmentVariable("DB_PASS"), // e.g. 'my-db-password'
                Database = Environment.GetEnvironmentVariable("DB_NAME"), // e.g. 'my-database'
                ConnectionProtocol = MySqlConnectionProtocol.UnixSocket
            };
            connectionString.Pooling = true;
            // Specify additional properties here.
            return connectionString;
        }
    }
}

Go

To see this snippet in the context of a web application, view the README on GitHub.

package cloudsql

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

	_ "github.com/go-sql-driver/mysql"
)

// connectUnixSocket initializes a Unix socket connection pool for
// a Cloud SQL instance of MySQL.
func connectUnixSocket() (*sql.DB, error) {
	mustGetenv := func(k string) string {
		v := os.Getenv(k)
		if v == "" {
			log.Fatalf("Fatal Error in connect_unix.go: %s environment variable not set.", 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 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'
		unixSocketPath = mustGetenv("INSTANCE_UNIX_SOCKET") // e.g. '/cloudsql/project:region:instance'
	)

	dbURI := fmt.Sprintf("%s:%s@unix(%s)/%s?parseTime=true",
		dbUser, dbPwd, unixSocketPath, dbName)

	// dbPool is the pool of database connections.
	dbPool, err := sql.Open("mysql", dbURI)
	if err != nil {
		return nil, fmt.Errorf("sql.Open: %w", err)
	}

	// ...

	return dbPool, nil
}

Ruby

To see this snippet in the context of a web application, view the README on GitHub.

unix: &unix
  adapter: mysql2
  # Configure additional properties here.
  # 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 secrets safe.
  username: <%= ENV["DB_USER"] %>  # e.g. "my-database-user"
  password: <%= ENV["DB_PASS"] %> # e.g. "my-database-password"
  database: <%= ENV.fetch("DB_NAME") { "vote_development" } %>
  # Specify the Unix socket path as host
  socket: "<%= ENV["INSTANCE_UNIX_SOCKET"] %>"

PHP

To see this snippet in the context of a web application, view the README on GitHub.

namespace Google\Cloud\Samples\CloudSQL\MySQL;

use PDO;
use PDOException;
use RuntimeException;
use TypeError;

class DatabaseUnix
{
    public static function initUnixDatabaseConnection(): PDO
    {
        try {
            // 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 secrets safe.
            $username = getenv('DB_USER'); // e.g. 'your_db_user'
            $password = getenv('DB_PASS'); // e.g. 'your_db_password'
            $dbName = getenv('DB_NAME'); // e.g. 'your_db_name'
            $instanceUnixSocket = getenv('INSTANCE_UNIX_SOCKET'); // e.g. '/cloudsql/project:region:instance'

            // Connect using UNIX sockets
            $dsn = sprintf(
                'mysql:dbname=%s;unix_socket=%s',
                $dbName,
                $instanceUnixSocket
            );

            // Connect to the database.
            $conn = new PDO(
                $dsn,
                $username,
                $password,
                # ...
            );
        } catch (TypeError $e) {
            throw new RuntimeException(
                sprintf(
                    'Invalid or missing configuration! Make sure you have set ' .
                        '$username, $password, $dbName, ' .
                        'and $instanceUnixSocket (for UNIX socket mode). ' .
                        'The PHP error was %s',
                    $e->getMessage()
                ),
                (int) $e->getCode(),
                $e
            );
        } catch (PDOException $e) {
            throw new RuntimeException(
                sprintf(
                    'Could not connect to the Cloud SQL Database. Check that ' .
                        'your username and password are correct, that the Cloud SQL ' .
                        'proxy is running, and that the database exists and is ready ' .
                        'for use. For more assistance, refer to %s. The PDO error was %s',
                    'https://cloud.google.com/sql/docs/mysql/connect-external-app',
                    $e->getMessage()
                ),
                (int) $e->getCode(),
                $e
            );
        }

        return $conn;
    }
}

Connect with Cloud SQL connectors

The Cloud SQL connectors are language specific libraries that provide encryption and IAM-based authorization when connecting to a Cloud SQL instance.

Python

To see this snippet in the context of a web application, view the README on GitHub.

import os

from google.cloud.sql.connector import Connector, IPTypes
import pymysql

import sqlalchemy


def connect_with_connector() -> sqlalchemy.engine.base.Engine:
    """
    Initializes a connection pool for a Cloud SQL instance of MySQL.

    Uses the Cloud SQL Python Connector package.
    """
    # 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 secrets safe.

    instance_connection_name = os.environ[
        "INSTANCE_CONNECTION_NAME"
    ]  # e.g. 'project:region:instance'
    db_user = os.environ["DB_USER"]  # e.g. 'my-db-user'
    db_pass = os.environ["DB_PASS"]  # e.g. 'my-db-password'
    db_name = os.environ["DB_NAME"]  # e.g. 'my-database'

    ip_type = IPTypes.PRIVATE if os.environ.get("PRIVATE_IP") else IPTypes.PUBLIC

    connector = Connector(ip_type)

    def getconn() -> pymysql.connections.Connection:
        conn: pymysql.connections.Connection = connector.connect(
            instance_connection_name,
            "pymysql",
            user=db_user,
            password=db_pass,
            db=db_name,
        )
        return conn

    pool = sqlalchemy.create_engine(
        "mysql+pymysql://",
        creator=getconn,
        # ...
    )
    return pool

Java

To see this snippet in the context of a web application, view the README on GitHub.

Note:

• INSTANCE_CONNECTION_NAME should be represented as <MY-PROJECT>:<INSTANCE-REGION>:<INSTANCE-NAME>
• See the JDBC socket factory version requirements for the pom.xml file here .

import com.zaxxer.hikari.HikariConfig;
import com.zaxxer.hikari.HikariDataSource;
import javax.sql.DataSource;

public class ConnectorConnectionPoolFactory extends ConnectionPoolFactory {

  // 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 secrets safe.
  private static final String INSTANCE_CONNECTION_NAME =
      System.getenv("INSTANCE_CONNECTION_NAME");
  private static final String INSTANCE_UNIX_SOCKET = System.getenv("INSTANCE_UNIX_SOCKET");
  private static final String DB_USER = System.getenv("DB_USER");
  private static final String DB_PASS = System.getenv("DB_PASS");
  private static final String DB_NAME = System.getenv("DB_NAME");

  public static DataSource createConnectionPool() {
    // The configuration object specifies behaviors for the connection pool.
    HikariConfig config = new HikariConfig();

    // The following URL is equivalent to setting the config options below:
    // jdbc:mysql:///<DB_NAME>?cloudSqlInstance=<INSTANCE_CONNECTION_NAME>&
    // socketFactory=com.google.cloud.sql.mysql.SocketFactory&user=<DB_USER>&password=<DB_PASS>
    // See the link below for more info on building a JDBC URL for the Cloud SQL JDBC Socket Factory
    // https://github.com/GoogleCloudPlatform/cloud-sql-jdbc-socket-factory#creating-the-jdbc-url

    // Configure which instance and what database user to connect with.
    config.setJdbcUrl(String.format("jdbc:mysql:///%s", DB_NAME));
    config.setUsername(DB_USER); // e.g. "root", "mysql"
    config.setPassword(DB_PASS); // e.g. "my-password"

    config.addDataSourceProperty("socketFactory", "com.google.cloud.sql.mysql.SocketFactory");
    config.addDataSourceProperty("cloudSqlInstance", INSTANCE_CONNECTION_NAME);


    // The ipTypes argument can be used to specify a comma delimited list of preferred IP types
    // for connecting to a Cloud SQL instance. The argument ipTypes=PRIVATE will force the
    // SocketFactory to connect with an instance's associated private IP.
    config.addDataSourceProperty("ipTypes", "PUBLIC,PRIVATE");

    // ... Specify additional connection properties here.
    // ...

    // Initialize the connection pool using the configuration object.
    return new HikariDataSource(config);
  }
}

Go

To see this snippet in the context of a web application, view the README on GitHub.

package cloudsql

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

	"cloud.google.com/go/cloudsqlconn"
	"github.com/go-sql-driver/mysql"
)

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.", 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")
	)

	d, err := cloudsqlconn.NewDialer(context.Background())
	if err != nil {
		return nil, fmt.Errorf("cloudsqlconn.NewDialer: %w", err)
	}
	var opts []cloudsqlconn.DialOption
	if usePrivate != "" {
		opts = append(opts, cloudsqlconn.WithPrivateIP())
	}
	mysql.RegisterDialContext("cloudsqlconn",
		func(ctx context.Context, addr string) (net.Conn, error) {
			return d.Dial(ctx, instanceConnectionName, opts...)
		})

	dbURI := fmt.Sprintf("%s:%s@cloudsqlconn(localhost:3306)/%s?parseTime=true",
		dbUser, dbPwd, dbName)

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

Private IP

Connect with TCP

Connect using the private IP address of your Cloud SQL instance as the host and port 3306.

Python

To see this snippet in the context of a web application, view the README on GitHub.

import os

import sqlalchemy


def connect_tcp_socket() -> sqlalchemy.engine.base.Engine:
    """Initializes a TCP connection pool for a Cloud SQL instance of MySQL."""
    # 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 secrets safe.
    db_host = os.environ[
        "INSTANCE_HOST"
    ]  # e.g. '127.0.0.1' ('172.17.0.1' if deployed to GAE Flex)
    db_user = os.environ["DB_USER"]  # e.g. 'my-db-user'
    db_pass = os.environ["DB_PASS"]  # e.g. 'my-db-password'
    db_name = os.environ["DB_NAME"]  # e.g. 'my-database'
    db_port = os.environ["DB_PORT"]  # e.g. 3306

    pool = sqlalchemy.create_engine(
        # Equivalent URL:
        # mysql+pymysql://<db_user>:<db_pass>@<db_host>:<db_port>/<db_name>
        sqlalchemy.engine.url.URL.create(
            drivername="mysql+pymysql",
            username=db_user,
            password=db_pass,
            host=db_host,
            port=db_port,
            database=db_name,
        ),
        # ...
    )
    return pool

Java

To see this snippet in the context of a web application, view the README on GitHub.

Note:

• INSTANCE_CONNECTION_NAME should be represented as <MY-PROJECT>:<INSTANCE-REGION>:<INSTANCE-NAME>
• Using the argument ipTypes=PRIVATE will force the SocketFactory to connect with an instance's associated private IP
• See the JDBC socket factory version requirements for the pom.xml file here .

import com.zaxxer.hikari.HikariConfig;
import com.zaxxer.hikari.HikariDataSource;
import javax.sql.DataSource;

public class TcpConnectionPoolFactory extends ConnectionPoolFactory {

  // Saving credentials in environment variables is convenient, but not secure - consider a more
  // secure solution such as https://cloud.google.com/secret-manager/ to help keep secrets safe.
  private static final String DB_USER = System.getenv("DB_USER");
  private static final String DB_PASS = System.getenv("DB_PASS");
  private static final String DB_NAME = System.getenv("DB_NAME");

  private static final String INSTANCE_HOST = System.getenv("INSTANCE_HOST");
  private static final String DB_PORT = System.getenv("DB_PORT");


  public static DataSource createConnectionPool() {
    // The configuration object specifies behaviors for the connection pool.
    HikariConfig config = new HikariConfig();

    // The following URL is equivalent to setting the config options below:
    // jdbc:mysql://<INSTANCE_HOST>:<DB_PORT>/<DB_NAME>?user=<DB_USER>&password=<DB_PASS>
    // See the link below for more info on building a JDBC URL for the Cloud SQL JDBC Socket Factory
    // https://github.com/GoogleCloudPlatform/cloud-sql-jdbc-socket-factory#creating-the-jdbc-url

    // Configure which instance and what database user to connect with.
    config.setJdbcUrl(String.format("jdbc:mysql://%s:%s/%s", INSTANCE_HOST, DB_PORT, DB_NAME));
    config.setUsername(DB_USER); // e.g. "root", "mysql"
    config.setPassword(DB_PASS); // e.g. "my-password"


    // ... Specify additional connection properties here.
    // ...

    // Initialize the connection pool using the configuration object.
    return new HikariDataSource(config);
  }
}

Node.js

To see this snippet in the context of a web application, view the README on GitHub.

const mysql = require('promise-mysql');
const fs = require('fs');

// createTcpPool initializes a TCP connection pool for a Cloud SQL
// instance of MySQL.
const createTcpPool = async config => {
  // 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 secrets safe.
  const dbConfig = {
    host: process.env.INSTANCE_HOST, // e.g. '127.0.0.1'
    port: process.env.DB_PORT, // e.g. '3306'
    user: process.env.DB_USER, // e.g. 'my-db-user'
    password: process.env.DB_PASS, // e.g. 'my-db-password'
    database: process.env.DB_NAME, // e.g. 'my-database'
    // ... Specify additional properties here.
    ...config,
  };
  // Establish a connection to the database.
  return mysql.createPool(dbConfig);
};

Go

To see this snippet in the context of a web application, view the README on GitHub.

package cloudsql

import (
	"crypto/tls"
	"crypto/x509"
	"database/sql"
	"errors"
	"fmt"
	"log"
	"os"

	"github.com/go-sql-driver/mysql"
)

// connectTCPSocket initializes a TCP connection pool for a Cloud SQL
// instance of MySQL.
func connectTCPSocket() (*sql.DB, error) {
	mustGetenv := func(k string) string {
		v := os.Getenv(k)
		if v == "" {
			log.Fatalf("Fatal Error in connect_tcp.go: %s environment variable not set.", 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 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'
		dbPort    = mustGetenv("DB_PORT")       // e.g. '3306'
		dbTCPHost = mustGetenv("INSTANCE_HOST") // e.g. '127.0.0.1' ('172.17.0.1' if deployed to GAE Flex)
	)

	dbURI := fmt.Sprintf("%s:%s@tcp(%s:%s)/%s?parseTime=true",
		dbUser, dbPwd, dbTCPHost, dbPort, dbName)


	// dbPool is the pool of database connections.
	dbPool, err := sql.Open("mysql", dbURI)
	if err != nil {
		return nil, fmt.Errorf("sql.Open: %w", err)
	}

	// ...

	return dbPool, nil
}

C#

To see this snippet in the context of a web application, view the README on GitHub.

using MySql.Data.MySqlClient;
using System;

namespace CloudSql
{
    public class MySqlTcp
    {
        public static MySqlConnectionStringBuilder NewMysqlTCPConnectionString()
        {
            // Equivalent connection string:
            // "Uid=<DB_USER>;Pwd=<DB_PASS>;Host=<INSTANCE_HOST>;Database=<DB_NAME>;"
            var connectionString = new MySqlConnectionStringBuilder()
            {
                // 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 secrets safe.
                Server = Environment.GetEnvironmentVariable("INSTANCE_HOST"),   // e.g. '127.0.0.1'
                // Set Host to 'cloudsql' when deploying to App Engine Flexible environment
                UserID = Environment.GetEnvironmentVariable("DB_USER"),   // e.g. 'my-db-user'
                Password = Environment.GetEnvironmentVariable("DB_PASS"), // e.g. 'my-db-password'
                Database = Environment.GetEnvironmentVariable("DB_NAME"), // e.g. 'my-database'

                // The Cloud SQL proxy provides encryption between the proxy and instance.
                SslMode = MySqlSslMode.Disabled,
            };
            connectionString.Pooling = true;
            // Specify additional properties here.
            return connectionString;

        }
    }
}

Ruby

To see this snippet in the context of a web application, view the README on GitHub.

tcp: &tcp
  adapter: mysql2
  # Configure additional properties here
  # 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 secrets safe.
  username: <%= ENV["DB_USER"] %>  # e.g. "my-database-user"
  password: <%= ENV["DB_PASS"] %> # e.g. "my-database-password"
  database: <%= ENV.fetch("DB_NAME") { "vote_development" } %>
  host: "<%= ENV.fetch("INSTANCE_HOST") { "127.0.0.1" }%>" # '172.17.0.1' if deployed to GAE Flex
  port: <%= ENV.fetch("DB_PORT") { 3306 }%>

PHP

To see this snippet in the context of a web application, view the README on GitHub.

namespace Google\Cloud\Samples\CloudSQL\MySQL;

use PDO;
use PDOException;
use RuntimeException;
use TypeError;

class DatabaseTcp
{
    public static function initTcpDatabaseConnection(): PDO
    {
        try {
            // 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 secrets safe.
            $username = getenv('DB_USER'); // e.g. 'your_db_user'
            $password = getenv('DB_PASS'); // e.g. 'your_db_password'
            $dbName = getenv('DB_NAME'); // e.g. 'your_db_name'
            $instanceHost = getenv('INSTANCE_HOST'); // e.g. '127.0.0.1' ('172.17.0.1' for GAE Flex)

            // Connect using TCP
            $dsn = sprintf('mysql:dbname=%s;host=%s', $dbName, $instanceHost);

            // Connect to the database
            $conn = new PDO(
                $dsn,
                $username,
                $password,
                # ...
            );
        } catch (TypeError $e) {
            throw new RuntimeException(
                sprintf(
                    'Invalid or missing configuration! Make sure you have set ' .
                        '$username, $password, $dbName, and $instanceHost (for TCP mode). ' .
                        'The PHP error was %s',
                    $e->getMessage()
                ),
                $e->getCode(),
                $e
            );
        } catch (PDOException $e) {
            throw new RuntimeException(
                sprintf(
                    'Could not connect to the Cloud SQL Database. Check that ' .
                        'your username and password are correct, that the Cloud SQL ' .
                        'proxy is running, and that the database exists and is ready ' .
                        'for use. For more assistance, refer to %s. The PDO error was %s',
                    'https://cloud.google.com/sql/docs/mysql/connect-external-app',
                    $e->getMessage()
                ),
                $e->getCode(),
                $e
            );
        }

        return $conn;
    }
}

Best practices and other information

You can use the Cloud SQL Auth Proxy when testing your application locally. See the quickstart for using the Cloud SQL Auth Proxy for detailed instructions.

Connection Pools

Connections to underlying databases may be dropped, either by the database server itself, or by the underlying infrastructure. To mitigate this, we recommend that you use a client library that supports connection pools and automatic reconnection.

Connection Limits

Each App Engine instance running in a standard environment cannot have more than 100 concurrent connections to an instance. For PHP 5.5 apps, the limit is 60 concurrent connections. This limit applies per application instance. This means that each instance of the App Engine application can have that many connections to the database, and as it scales the total number of connections per deployment can grow. For more information, see Scaling elements.

You can limit the maximum number of connections used per instance by using a connection pool. For more detailed examples on how to limit the number of connections, see the Managing database connections page.

App Engine applications are subject to request time limits depending on usage and environment. For more information, see how instances are managed in App Engine standard environment standard and flexible environments.

API Quota Limits

App Engine provides a mechanism that connects using the Cloud SQL Auth Proxy, which uses the Cloud SQL Admin API. API quota limits apply to the Cloud SQL Auth Proxy. When the Cloud SQL Admin API starts, it uses a quota of two and an average of two per hour afterwards. The default quota is 180 per minute per user. App Engine applications are also subject to additional quotas and limits as discussed on the App Engine Quotas page.