Connectivity between Cloud Run and Cloud SQL (Internal IP) - google-cloud-sql

Question

I have created my organisation infrastructure in GCP following the Cloud Foundation Toolkit using the Terraform modules provided by Google.
The following table list the IP ranges for all environments:
Now I am in the process of deploying my application that consists of basically Cloud Run services and a Cloud SQL (Postgres) instance.
The Cloud SQL instance was created with a private IP from the "unallocated" IP range that is reserved for peered services (such as Cloud SQL).
In order to establish connectivity between Cloud Run and Cloud SQL, I have also created the Serverless VPC Connector (ip range 10.1.0.16/28) and configured the Cloud SQL proxy.
When I try to connect to the database from the Cloud Run service I get this error after ~10s:
CloudSQL connection failed. Please see https://cloud.google.com/sql/docs/mysql/connect-run for additional details: Post "https://www.googleapis.com/sql/v1beta4/projects/[my-project]/instances/platform-db/createEphemeral?alt=json&prettyPrint=false": context deadline exceeded
I have granted roles/vpcaccess.user for both the default Cloud Run SA and the one used by the application in the host project.
I have granted roles/compute.networkUser for both SAs in the service project. I also granted roles/cloudsql.client for both SAs.
I have enabled servicenetworking.googleapis.com and vpcaccess.googleapis.com in the service project.
I have run out of ideas and I can't figure out what the issue is.
It seems like a timeout error when Cloud Run tries to create a POST request to the Cloud SQL API. So it seems like the VPC connector (10.1.0.16/28) cannot connect to the Cloud SQL instance (10.0.80.0/20).
Has anyone experienced this issue before?

Answer 1

When you use the Cloud SQL built-in connexion in Cloud Run (but also App Engine and Cloud Function) a connexion similar to Cloud SQL proxy is created. This connexion can be achieved only on a Cloud SQL public IP, even if you have a serverless VPC connector and your database reachable through the VPC.
If you have only a private IP on Cloud SQL, you need to use the private IP to reach the database, not the built-in Cloud SQL connector. More detail in the documentation
I also wrote an article on this

Answer 2

If you are using a private IP, you need to check the docker bridge network's IP range. Here is what the documentation says:
If a client cannot connect to the Cloud SQL instance using private IP, check to see if the client is using any IP in the range 172.17.0.0/16. Connections fail from any IP within the 172.17.0.0/16 range to Cloud SQL instances using private IP. Similarly, Cloud SQL instances created with an IP in that range are unreachable. This range is reserved for the docker bridge network.
To resolve some of the issues, you are experiencing, follow the documentation here and post any error messages you receive, for example, you could try:
Try the gcloud sql connect command to connect to your instance. This command authorizes your IP address for a short time. You can run this command in an environment with Cloud SDK and mysql client installed. You can also run this command in Cloud Shell, which is available in the Google Cloud Console and has Cloud SDK and the mysql client pre-installed.
Temporarily allow all IP addresses to connect to an instance. For IPv4 authorize 0.0.0.0/0 (for IPv6, authorize ::/0. After you have tested this, please make sure you remove it again as it opens up to the world!
Are you using connection pools?
If not, I would create a cache of connections so that when your application needs to link to the database, it can get a temporary connection from the pool. Once the application has finished its operation, the connection returns to the pool again for later use. For this to work correctly, the connection needs to be open and closed efficiently and not waste any resources.