ALB and gRPC keep alive pings to keep a gRPC stream open

Hi,

I have a Fargate instance running a gRPC API (written with Spring Boot) running behind of an AWS ALB (ALB listens on port 9090 / HTTPS, target group uses HTTP / 9090 and protocol gRPC). The client, that I am using, is able to communicate with the gRPC server. We also instantiate a server stream to the client that needs to stay open, because the server needs to send some data with low latency to the client. However, after 60 seconds the stream will be terminated (default timeout of the ALB). To prevent that, I have configured the client to send keep alive pings every 20 seconds, but that does not work. I also tried to use server side keep alive pings, however, that was not working either. To verify that the pings are send to the server, I used Wireshark and it seems that at least the client side keep alive pings work.

Does the ALB support keep alive pings to keep the gRPC stream open? Are there any best practices on how to set up gRPC streams with the ALB?

Thanks in advance :-).