Why Use Cloud Load Balancer for WebSocket Connections from Cloud Run?

I'm successfully creating a WebSocket connection from a GCP Cloud Run instance to an external system. I've strictly followed the official GCP documentation and everything is working as expected.

However, the documentation also recommends using a Cloud Load Balancer in front of the Cloud Run service to initiate WebSocket connections. Unfortunately, it doesn't provide a clear explanation for why this is necessary.

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Could someone please clarify the specific benefits or reasons for using a Cloud Load Balancer in this scenario? Are there any potential drawbacks or performance implications to consider when using a load balancer for WebSocket connections?

Link to the doc

Any insights or explanations would be greatly appreciated.

Cloud Run only supports HTTPS connections, it does not support raw TCP ports. You could use an intermediary service to handle raw TCP and translate those requests into HTTPS. Theoretically a load balancer could easily translate TCP connections to one of those.

Cloud Run just supports HTTP, WebSockets and gRPC and not TCP. You can have Cloud Run communicate to other GCP services in the VPC by using a Serverless VPC Connector or expose it with an internal IP address behind a load balancer.

You can also use Load balancer and Google provided Cloud Armor to protect against the DDoS attacks without compromising the scaling of Cloud Run.

If the resource is a Cloud VPN gateway with users or on-prem services unable to access the service (despite being on the same project and/or VPC perimeter), one can use Private Service Connect or Internal Load Balancer.

Websocket connections can be up for a long time. Backend service timeout behaves differently for HTTP and TCP/SSL Proxy. If you want to have very long Websocket connections, then you should use Network Load Balancing.

Overall GCP Load Balancer can significantly improve the availability, scalability, and security of your WebSocket connections from Cloud Run. On the other hand while the Load Balancer adds a small amount of latency, its benefits generally outweigh this minor drawback.

Refer to Cloud Load Balancing: A comprehensive solution for secure and private access to Cloud Run services and for examples check Deploy a secured serverless architecture using Cloud Run for more information.