Connect your instance to multiple VPCs

MySQL   |  PostgreSQL   |  SQL Server

This page describes how to connect to your Cloud SQL instance across transitively peered VPCs.

Cloud SQL offers the following ways to connect your Cloud SQL instance to multiple VPCs using private IP:

• Connect using custom advertised routes
• Connect using an intermediate proxy (SOCKS5)
• Connect using Proxy as a service
• Connect using Private Service Connect

Connect using custom advertised routes

You can use Cloud Router to configure custom advertised routes between two networks that go through an intermediate VPC to connect multiple VPCs to your Cloud SQL instance. The two VPCs must be connected using a virtual private network (VPN), Cloud Interconnect , or any other Cloud Router supported network.

With custom advertised routes, your Cloud SQL VPC, VPC C, is connected to your main VPC, VPC A, using an intermediate VPC, VPC B. You can configure shared routes between these networks in the following ways:

• You can use Cloud Router to manually advertise routes between two networks that go through an intermediate VPC. For more information on how to configure Cloud Router to manually advertise routes, see Transit network.

• You can create two HA VPC gateways that connect to each other to bridge the two different VPCs and configure Cloud Router to share routes between them. For more information on how to set up HA VPC gateways, see Create HA VPC gateways to connect VPC networks.

We recommend using custom advertised routes to connect multiple VPCs to your Cloud SQL instance using Cloud Router.

Connect using an intermediate proxy (SOCKS5)

You can set up an intermediate proxy, such as SOCKS5 proxy, on an intermediate VPC along with the Cloud SQL Auth Proxy in your main VPC between the client and your Cloud SQL instance. This enables the intermediate node to forward encrypted traffic from the Cloud SQL Auth Proxy to the Cloud SQL instance.

To use an intermediary proxy to connect to your Cloud SQL instance from multiple VPCs, follow these steps:

1. On your external client, install gcloud CLI.

2. On the intermediary VM, install, configure, and run a SOCKS server. One example of this server is Dante, a popular open source solution.

3. Configure the server to bind to the VM's ens4 network interface for both external and internal connections. For internal connections, specify any port.

4. Configure your VPC's firewall to allow TCP traffic from the appropriate IP address or range to the SOCKS server's configured port.

5. On your external client, download and install the Cloud SQL Auth Proxy.

6. On your external client, start the Cloud SQL Auth Proxy.

   Because you configured your instance to use an internal IP address, when you start the Cloud SQL Auth Proxy, you must provide the --private-ip option.

   Also, set the ALL_PROXY environment variable to the intermediary VM's IP address and specify the port that the SOCKS server uses. For example, ALL_PROXY=socks5://VM_IP_ADDRESS:SOCKS_SERVER_PORT.

   Note: The default port for the SOCKS server is 1080.

   If you're connecting from a peered VPC, then use the intermediary VM's internal IP address; otherwise, use its external IP address.

7. On your external client, test your connection using mysql.

Connect using the Cloud SQL Auth Proxy as a service

You can install and run the Cloud SQL Auth Proxy on your intermediate VPC instead of your external client and enable secure connections by pairing it with a protocol-aware proxy, also known as a connection pooler. Examples of connection poolers include PGbouncer, or Pgpool-II(PostgreSQL only).

This connection method allows your applications to securely connect directly to the pooler using a configured SSL. The pooler passes databases queries to your Cloud SQL instance using the Cloud SQL Auth Proxy.

Note: You'll need to set up your own secure connection. These connections aren't secured by Cloud SQL.

Connect using Private Service Connect

Private Service Connect allows you to connect to multiple VPC networks across different projects or organizations. You can use Private Service Connect to connect to either a primary instance or any of its read replicas. For more information about Private Service Connect, see Private Service Connect overview.

To connect across multiple VPCs using Private Service Connect, see Connect to an instance using Private Service Connect.