RAG cannot be deployed on an existing cluster due to CloudSQL requiring at least 1 private service connection

[andrewsykim]

Trying to deploy RAG on an existing cluster results in this error:

Step #0 - "Apply blueprint": on .terraform/modules/jupyterhub.jupyterhub-workload-identity/modules/workload-identity/main.tf line 51
Step #0 - "Apply blueprint": 
Step #0 - "Apply blueprint": time="2024-04-02T14:44:14Z" level=error msg="error writing to GCS: error closing temp logfile: googleapi: got HTTP response code 503 with body: Service Unavailable"
Step #0 - "Apply blueprint": Error: Error, failed to create instance because the network doesn't have at least 1 private services connection. Please see https://cloud.google.com/sql/docs/mysql/private-ip#network_requirements for how to create this connection.
Step #0 - "Apply blueprint": time="2024-04-02T14:44:14Z" level=error msg="Error (exit code 1) running \"terraform apply -json /tmp/tfplan-2667148229/plan.out\". Stderr:\n"
Step #0 - "Apply blueprint": Error: Error, failed to create instance because the network doesn't have at least 1 private services connection. Please see https://cloud.google.com/sql/docs/mysql/private-ip#network_requirements for how to create this connection.
Step #0 - "Apply blueprint": error: Error, failed to create instance because the network doesn't have at least 1 private services connection. Please see https://cloud.google.com/sql/docs/mysql/private-ip#network_requirements for how to create this connection.
Step #0 - "Apply blueprint": 
Step #0 - "Apply blueprint": on .terraform/modules/cloudsql.cloudsql/modules/postgresql/main.tf line 54

I think this is because we only create the private service connection when creating new networks, which doesn't execute when trying to run the RAG deployment on an existing cluster