Connecting from Cloud Functions to Cloud SQL

This page contains information and examples for connecting to a Cloud SQL instance from a service running in Cloud Functions.

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

Cloud Functions is a lightweight compute solution for developers to create single-purpose, standalone functions that responds to Cloud events without the need to manage a server or runtime environment.

Setting up a Cloud SQL instance

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

    Enable the API

  2. Create a Cloud SQL for SQL Server instance.

    By default, Cloud SQL assigns a public IP address to a new instance. Cloud Functions does not support connecting to Cloud SQL for SQL Server over public IP. Use private IP instead. For more information, see Configuring private IP.

Configuring Cloud Functions

The steps to configure Cloud Functions depend on the type of IP address you assigned to your Cloud SQL instance.

Public IP (default)

Cloud Functions does not support connecting to Cloud SQL for SQL Server over public IP. Use private IP instead.

Private IP

A Serverless VPC Access connector handles communication to your VPC network. To connect directly with private IP, you need to:

  1. Make sure that the Cloud SQL instance created above has a private IP address. If you need to add one, see the Configuring private IP page for instructions.
  2. Create a Serverless VPC Access connector in the same VPC network as your Cloud SQL instance.
  3. A connector must be in the same project and region as the resource that uses it, but the connector can send traffic to resources in different regions.

    Serverless VPC Access supports communication to VPC networks connected via Cloud VPN and VPC Network Peering.

    Serverless VPC Access does not support legacy networks or Shared VPC.

  4. Configure Cloud Functions to use the connector.
  5. Connect using your instance's private IP and port 1433.

Connecting to Cloud SQL

After you configure Cloud Functions, you can connect to your Cloud SQL instance. Cloud Functions provides a mechanism that connects using the Cloud SQL Proxy.

Public IP (default)

Cloud Functions does not support connecting to Cloud SQL for SQL Server over public IP. Use private IP instead.

Private IP

Connecting with TCP

Connect directly using the private IP address and port 1433 for your instance.

Best practices & other information

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

Connection Pools

Connections to underlying databases may be dropped, either by the database server itself, or by the infrastructure underlying Cloud Functions. We recommend using a client library that supports connection pools that automatically reconnect broken client connections. Additionally, we recommend using a globally scoped connection pool to increase the likelihood that your function reuses the same connection for subsequent invocations of the function, and closes the connection naturally when the instance is evicted (auto-scaled down). For more detailed examples on how to use connection pools, see Managing database connections.

Connection Limits

Cloud SQL imposes a maximum limit on concurrent connections, and these limits may vary depending on the database engine chosen (see Cloud SQL Quotas and Limits). When using a connection pool, it is important to set the maximum connections to 1.
  1. Cloud Functions limits concurrent executions to 1 per instance. You never have a situation where a single function instance is processing two requests at the same time. In most situations, only a single database connection is needed.
Where possible, you should take care to only initialize a connection pool for functions that need to use it. If a deployed function initializes a connection pool it doesn't need, it could create unused connections that count toward your quota. For more details on dealing with global variables in Cloud Functions, see Tips & Tricks. For more detailed examples on how to limit the number of connections, see Managing database connections.

API Quota Limits

Cloud Functions provides a mechanism that connects using the Cloud SQL Proxy, which uses the Cloud SQL Admin API. API quota limits apply to the Cloud SQL Proxy.