Configure connectivity using reverse SSH tunnel

Establish connectivity from the destination database to the source database through a secure reverse SSH tunnel. This method requires a bastion host VM in the Google Cloud project as well as a machine (for example, a laptop on the network) that has connectivity to the source database.

The Database Migration Service for MySQL collects the required information at migration creation time, and auto-generates the script for setting it all up.

See the following diagram:

Reverse SSH tunnel diagram

The following steps are performed in the Database Migration Service Create migration flow, to set up a reverse SSH tunnel between the source database and Cloud SQL instance. After you provide some parameters, you execute a set of gcloud commands on a machine which has connectivity to both the source database and to Google Cloud.

  1. Select the VM instance used to establish connectivity between the source database and the Cloud SQL instance. Typically this is a VM running in the VPC where the application accessing the new Cloud SQL database runs. The VM instance serves as the SSH tunnel bastion server.

  2. You can use an existing Compute Engine VM instance for this purpose.

    1. Choose the Compute Engine VM instance from the list.

    2. Provide a free port that the SSH tunnel can use.

  3. Alternatively, you can create a new VM at this step. Select CREATE A COMPUTE ENGINE VM INSTANCE and the generated script includes instructions to create it.

    1. Provide a name for the VM instance.

    2. Select a machine type for the VM.

    3. Specify a subnet for the VM

  4. Click VIEW SCRIPT to view the generated script.

  5. Run the script on a machine that has access to both the source database and the Compute Engine VM. The script performs the following operations:

    • Configures the Compute Engine VM as an SSH tunnel bastion server.

    • Establishes a secure SSH connection between the source database and the VPC.

    • If you're creating a new Compute Engine VM, then after successfully running the script, copy the VM server IP from the script output and enter it in the provided text field. The Cloud SQL instance will be updated as needed when you later test or start the migration job.


  7. Verify your migration job to confirm that it correctly migrated data from your source database instance to the destination Cloud SQL database instance.

  8. If your source is within a VPN (in AWS, for example, or your own on-premises VPN), proceed to the section on connecting VPCs through VPNs for more information on configuring the source VPN and Google Cloud VPN to work with each other.

  9. After your migration job is configured, connectivity is verified, and VPNs are configured successfully if necessary, then you can run the job.