Run gRPC APIs on Datum

[savme]

We've added HTTP/2 from client to origin on the Application Load Balancer (ALB), so you can run a gRPC API on Datum and call it at its ALB hostname.

Highlights:

• gRPC on Compute – add --http2 when you deploy, and the workload's ALB is ready for gRPC clients. The setting stays on through later deploys.
• gRPC to network service origins – mark a network service port as HTTP/2, and any ALB that uses it as an origin serves gRPC.
• Every hostname – generated hostnames and custom hostnames both serve HTTP/2, and HTTP/1.1 clients and browsers keep working unchanged.
• TLS handled for you – your server speaks plain gRPC, and the ALB terminates TLS.

Deploy a gRPC API on Compute

Requires the compute plugin v0.12.11 or later. To upgrade, run datumctl plugin upgrade compute.

To try it, deploy the helloworld Greeter from the official gRPC Go examples:

datumctl compute deploy grpc-hello --image=ghcr.io/datum-labs/compute-hello:grpc \ 
  --location=us-central-1 --http-port=50051 --http2

The deploy ends by printing the workload's URL. Call the Greeter there with grpcurl or any other gRPC client on port 443:

grpcurl -d '{"name": "Datum"}' <generated-hostname>:443 helloworld.Greeter/SayHello

The output is similar to the following:

{ "message": "Hello Datum" }

Use a network service as a gRPC origin

Requires the network and alb plugins v0.32.26 or later.

datumctl network service create api --selector app=api --port name=grpc,port=9090,app-protocol=h2c
datumctl alb create api --network-service api --port grpc

Things to know

• HTTP/2 to your server works for Compute workloads and network services. An origin you add by URL, such as a server outside Datum, is still reached over HTTP/1.1.
• If your app also uses WebSockets, serve them on a separate port without HTTP/2, because most servers don't accept WebSockets over HTTP/2.

Read the background in gRPC workloads on Datum Compute