Cloud SQL Go Connector

The Cloud SQL Go Connector is a Cloud SQL connector designed for use with the
Go language. Using a Cloud SQL connector provides a native alternative to the
Cloud SQL Auth Proxy while providing the following benefits:

• IAM Authorization: uses IAM permissions to control who/what can connect to
  your Cloud SQL instances
• Improved Security: uses robust, updated TLS 1.3 encryption and
  identity verification between the client connector and the server-side proxy,
  independent of the database protocol.
• Convenience: removes the requirement to use and distribute SSL
  certificates, as well as manage firewalls or source/destination IP addresses.
• (optionally) IAM DB Authentication: provides support for
  Cloud SQL’s automatic IAM DB AuthN feature.

For users migrating from the Cloud SQL Proxy drivers, see the migration
guide.

For a quick example, try out the Go Connector in a Codelab.

Installation

You can install this repo with go get:

go get cloud.google.com/go/cloudsqlconn

Usage

This package provides several functions for authorizing and encrypting
connections. These functions can be used with your database driver to connect to
your Cloud SQL instance.

The instance connection name for your Cloud SQL instance is always in the
format project:region:instance.

APIs and Services

This package requires the following to successfully make Cloud SQL Connections:

• IAM principal (user, service account, etc.) with the
  Cloud SQL Client role or equivalent. This IAM principal will
  be used for credentials.
• The Cloud SQL Admin API to be enabled within your Google Cloud
  Project. By default, the API will be called in the project associated with
  the IAM principal.

Credentials

This project uses the Application Default Credentials (ADC) strategy for
resolving credentials. Please see these instructions for how to set your ADC
(Google Cloud Application vs Local Development, IAM user vs service account credentials),
or consult the golang.org/x/oauth2/google documentation.

To explicitly set a specific source for the Credentials, see Using
Options below.

Connecting to a database

Postgres

Postgres users have the option of using the database/sql interface or
using pgx directly. See pgx's advice on which to choose.

Using the dialer with pgx

To use the dialer with pgx, we recommend using connection pooling with
pgxpool by configuring
a Config.DialFunc like so:

import (
    "context"
    "net"

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

func connect() {
    // Configure the driver to connect to the database
    dsn := "user=myuser password=mypass dbname=mydb sslmode=disable"
    config, err := pgxpool.ParseConfig(dsn)
    if err != nil {
        /* handle error */
    }

    // Create a new dialer with any options
    d, err := cloudsqlconn.NewDialer(context.Background())
    if err != nil {
        /* handle error */
    }

    // Tell the driver to use the Cloud SQL Go Connector to create connections
    config.ConnConfig.DialFunc = func(ctx context.Context, _ string, instance string) (net.Conn, error) {
        return d.Dial(ctx, "project:region:instance")
    }

    // Interact with the driver directly as you normally would
    pool, err := pgxpool.NewWithConfig(context.Background(), config)
    if err != nil {
        /* handle error */
    }

    // call cleanup when you're done with the database connection
    cleanup := func() error { return d.Close() }
    // ... etc
}

Using the dialer with database/sql

To use database/sql, call pgxv5.RegisterDriver with any necessary Dialer
configuration. Note: the connection string must use the keyword/value format
with host set to the instance connection name. The returned cleanup func
will stop the dialer's background refresh goroutine and so should only be called
when you're done with the Dialer.

import (
    "database/sql"

    "cloud.google.com/go/cloudsqlconn"
    "cloud.google.com/go/cloudsqlconn/postgres/pgxv5"
)

func connect() {
    cleanup, err := pgxv5.RegisterDriver("cloudsql-postgres", cloudsqlconn.WithIAMAuthN())
    if err != nil {
        // ... handle error
    }
    // call cleanup when you're done with the database connection
    defer cleanup()

    db, err := sql.Open(
        "cloudsql-postgres",
        "host=project:region:instance user=myuser password=mypass dbname=mydb sslmode=disable",
    )
    // ... etc
}

MySQL

To use database/sql, use mysql.RegisterDriver with any necessary Dialer
configuration. The returned cleanup func
will stop the dialer's background refresh goroutine and so should only be called
when you're done with the Dialer.

import (
    "database/sql"

    "cloud.google.com/go/cloudsqlconn"
    "cloud.google.com/go/cloudsqlconn/mysql/mysql"
)

func connect() {
    cleanup, err := mysql.RegisterDriver("cloudsql-mysql", cloudsqlconn.WithCredentialsFile("key.json"))
    if err != nil {
        // ... handle error
    }
    // call cleanup when you're done with the database connection
    defer cleanup()

    db, err := sql.Open(
        "cloudsql-mysql",
        "myuser:mypass@cloudsql-mysql(project:region:instance)/mydb",
    )
    // ... etc
}

SQL Server

To use database/sql, use mssql.RegisterDriver with any necessary Dialer
configuration. The returned cleanup func
will stop the dialer's background refresh goroutine and so should only be called
when you're done with the Dialer.

import (
    "database/sql"

    "cloud.google.com/go/cloudsqlconn"
    "cloud.google.com/go/cloudsqlconn/sqlserver/mssql"
)

func connect() {
    cleanup, err := mssql.RegisterDriver("cloudsql-sqlserver", cloudsqlconn.WithCredentialsFile("key.json"))
    if err != nil {
        // ... handle error
    }
    // call cleanup when you're done with the database connection
    defer cleanup()

    db, err := sql.Open(
        "cloudsql-sqlserver",
        "sqlserver://user:password@localhost?database=mydb&cloudsql=project:region:instance",
    )
    // ... etc
}

Using Advanced Disaster Recovery and DNS domain names to identify instances

The connector can be configured to use DNS to look up an instance.
Use a DNS name managed by Cloud SQL Advanced Disaster Recovery,
or a domain name that you manage.

Using Advanced Recovery Write Endpoint DNS Name

Advanced Disaster Recovery
creates geographically distributed replicas of your Cloud SQL database instance. When you perform
switchover or failover on the database instance, the connector will gracefully disconnect from the
old primary instance and reconnect to the new primary instance.

Follow the instructions in Connect using Write Endpoint
to get the write endpoint DNS name for your primary instance. Then, use this write endpoint DNS
name to configure the connector.

Configure your DNS Records

The connector may be configured to use DNS that you define as well.

Add a DNS TXT record for the Cloud SQL instance to a private DNS server
or a private Google Cloud DNS Zone used by your application.

Note: You are strongly discouraged from adding DNS records for your
Cloud SQL instances to a public DNS server. This would allow anyone on the
internet to discover the Cloud SQL instance name.

For example: suppose you wanted to use the domain name
prod-db.mycompany.example.com to connect to your database instance
my-project:region:my-instance. You would create the following DNS record:

• Record type: TXT
• Name: prod-db.mycompany.example.com – This is the domain name used by the application
• Value: my-project:region:my-instance – This is the instance name

Configure the connector

Configure the connector as described above, replacing the connector ID with
the DNS name.

Adapting the MySQL + database/sql example above:

package main

import (
	"database/sql"

	"cloud.google.com/go/cloudsqlconn"
	"cloud.google.com/go/cloudsqlconn/mysql/mysql"
)

func connect() {
	cleanup, err := mysql.RegisterDriver("cloudsql-mysql",
		cloudsqlconn.WithDNSResolver())
	if err != nil {
		// ... handle error
	}
	// call cleanup when you're done with the database connection
	defer cleanup()

	db, err := sql.Open(
		"cloudsql-mysql",
		"myuser:mypass@cloudsql-mysql(prod-db.mycompany.example.com)/mydb",
	)
	// ... etc
}

Automatic fail-over using DNS domain names

When the connector is configured using a domain name, the connector will
periodically check if the DNS record for an instance changes. When the connector
detects that the domain name refers to a different instance, the connector will
close all open connections to the old instance. Subsequent connection attempts
will be directed to the new instance.

For example: suppose application is configured to connect using the
domain name prod-db.mycompany.example.com. Initially the corporate DNS
zone has a TXT record with the value my-project:region:my-instance. The
application establishes connections to the my-project:region:my-instance
Cloud SQL instance.

Then, to reconfigure the application to use a different database
instance, change the value of the prod-db.mycompany.example.com DNS record
from my-project:region:my-instance to my-project:other-region:my-instance-2

The connector inside the application detects the change to this
DNS record. Now, when the application connects to its database using the
domain name prod-db.mycompany.example.com, it will connect to the
my-project:other-region:my-instance-2 Cloud SQL instance.

The connector will automatically close all existing connections to
my-project:region:my-instance. This will force the connection pools to
establish new connections. Also, it may cause database queries in progress
to fail.

The connector will poll for changes to the DNS name every 30 seconds by default.
You may configure the frequency of the connections using the option
WithFailoverPeriod(d time.Duration). When this is set to 0, the connector will
disable polling and only check if the DNS record changed when it is
creating a new connection.

Using Options

If you need to customize something about the Dialer, you can initialize
directly with NewDialer:

d, err := cloudsqlconn.NewDialer(
    ctx,
    cloudsqlconn.WithCredentialsFile("key.json"),
)
if err != nil {
    log.Fatalf("unable to initialize dialer: %s", err)
}

conn, err := d.Dial(ctx, "project:region:instance")

For a full list of customizable behavior, see Option.

Using DialOptions

If you want to customize things about how the connection is created, use
Option:

conn, err := d.Dial(
    ctx,
    "project:region:instance",
    cloudsqlconn.WithPrivateIP(),
)

You can also use the WithDefaultDialOptions Option to specify
DialOptions to be used by default:

d, err := cloudsqlconn.NewDialer(
    ctx,
    cloudsqlconn.WithDefaultDialOptions(
        cloudsqlconn.WithPrivateIP(),
    ),
)

Automatic IAM Database Authentication

Connections using Automatic IAM database authentication are supported when
using Postgres or MySQL drivers.

Make sure to configure your Cloud SQL Instance to allow IAM authentication
and add an IAM database user.

A Dialer can be configured to connect to a Cloud SQL instance using
automatic IAM database authentication with the WithIAMAuthN Option
(recommended) or the WithDialIAMAuthN DialOption.

d, err := cloudsqlconn.NewDialer(ctx, cloudsqlconn.WithIAMAuthN())

When configuring the DSN for IAM authentication, the password field can be
omitted and the user field should be formatted as follows:

Postgres: For an IAM user account, this is the user's email address.
For a service account, it is the service account's email without the
.gserviceaccount.com domain suffix.

MySQL: For an IAM user account, this is the user's email address, without
the @ or domain name. For example, for test-user@gmail.com, set the
user field to test-user. For a service account, this is the service
account's email address without the @project-id.iam.gserviceaccount.com
suffix.

Example DSNs using the test-sa@test-project.iam.gserviceaccount.com
service account to connect can be found below.

Postgres:

dsn := "user=test-sa@test-project.iam dbname=mydb sslmode=disable"

MySQL:

dsn := "user=test-sa dbname=mydb sslmode=disable"

Enabling Metrics and Tracing

This library includes support for metrics and tracing using OpenCensus.
To enable metrics or tracing, you need to configure an exporter.
OpenCensus supports many backends for exporters.

Supported metrics include:

• cloudsqlconn/dial_latency: The distribution of dialer latencies (ms)
• cloudsqlconn/open_connections: The current number of open Cloud SQL
  connections
• cloudsqlconn/dial_failure_count: The number of failed dial attempts
• cloudsqlconn/refresh_success_count: The number of successful certificate
  refresh operations
• cloudsqlconn/refresh_failure_count: The number of failed refresh
  operations
• cloudsqlconn/bytes_sent: The number of bytes sent to Cloud SQL
• cloudsqlconn/bytes_received: The number of bytes received from Cloud SQL

Supported traces include:

• cloud.google.com/go/cloudsqlconn.Dial: The dial operation including
  refreshing an ephemeral certificate and connecting the instance
• cloud.google.com/go/cloudsqlconn/internal.InstanceInfo: The call to retrieve
  instance metadata (e.g., database engine type, IP address, etc)
• cloud.google.com/go/cloudsqlconn/internal.Connect: The connection attempt
  using the ephemeral certificate
• SQL Admin API client operations

For example, to use Cloud Monitoring and Cloud Trace, you would
configure an exporter like so:

import (
    "contrib.go.opencensus.io/exporter/stackdriver"
    "go.opencensus.io/trace"
)

func main() {
    sd, err := stackdriver.NewExporter(stackdriver.Options{
        ProjectID: "mycoolproject",
    })
    if err != nil {
        // handle error
    }
    defer sd.Flush()
    trace.RegisterExporter(sd)

    sd.StartMetricsExporter()
    defer sd.StopMetricsExporter()

    // Use cloudsqlconn as usual.
    // ...
}

As OpenTelemetry has now reached feature parity with OpenCensus, the migration
from OpenCensus to OpenTelemetry is strongly encouraged.
OpenTelemetry bridge
can be leveraged to migrate to OpenTelemetry without the need of replacing the
OpenCensus APIs in this library. Example code is shown below for migrating an
application using the OpenTelemetry bridge for traces.

import (
	texporter "github.com/GoogleCloudPlatform/opentelemetry-operations-go/exporter/trace"
	"go.opencensus.io/trace"
	"go.opentelemetry.io/otel"
	"go.opentelemetry.io/otel/bridge/opencensus"
	sdktrace "go.opentelemetry.io/otel/sdk/trace"
	"google.golang.org/api/option"
)

func main() {
	// trace.AlwaysSample() is expensive. Replacing it with your own
	// sampler for production environments is recommended.
	trace.ApplyConfig(trace.Config{DefaultSampler: trace.AlwaysSample()})

	exporter, err := texporter.New(
		texporter.WithTraceClientOptions([]option.ClientOption{option.WithTelemetryDisabled()}),
		texporter.WithProjectID("mycoolproject"),
	)
	if err != nil {
		// Handle error
	}

	tp := sdktrace.NewTracerProvider(sdktrace.WithSyncer(exporter))
	otel.SetTracerProvider(tp)
	tracer := tp.Tracer("Cloud SQL Go Connector Trace")
	trace.DefaultTracer = opencensus.NewTracer(tracer)

	// Use cloudsqlconn as usual.
	// ...
}

A known OpenTelemetry issue has been reported here.
It shouldn't impact database operations.

Debug Logging

The Go Connector supports optional debug logging to help diagnose problems with
the background certificate refresh. To enable it, provide a logger that
implements the debug.ContextLogger interface when initializing the Dialer.

For example:

import (
    "context"
    "net"

    "cloud.google.com/go/cloudsqlconn"
)

type myLogger struct{}

func (l *myLogger) Debugf(ctx context.Context, format string, args ...interface{}) {
    // Log as you like here
}

func connect() {
    l := &myLogger{}

    d, err := NewDialer(
        context.Background(),
        cloudsqlconn.WithContextDebugLogger(l),
    )
    // use dialer as usual...
}

Support policy

Major version lifecycle

This project uses semantic versioning, and uses the
following lifecycle regarding support for a major version:

Active - Active versions get all new features and security fixes (that
wouldn’t otherwise introduce a breaking change). New major versions are
guaranteed to be "active" for a minimum of 1 year.

Deprecated - Deprecated versions continue to receive security and critical
bug fixes, but do not receive new features. Deprecated versions will be
supported for 1 year.

Unsupported - Any major version that has been deprecated for >=1 year is
considered unsupported.

Supported Go Versions

We follow the Go Version Support Policy used by Google Cloud
Libraries for Go.

Release cadence

This project aims for a release on at least a monthly basis. If no new features
or fixes have been added, a new PATCH version with the latest dependencies is
released.