connect-go: Generate Connect RPC Handlers in CI

protoc-gen-connect-go generates Connect RPC Go handlers and clients that interoperate with gRPC and gRPC-Web over plain HTTP.

Connect (connectrpc.com) is a gRPC-compatible RPC framework. Its code generator, protoc-gen-connect-go, runs as a normal protoc/buf plugin alongside protoc-gen-go.

What it does

protoc-gen-connect-go produces *.connect.go files with Connect handlers and clients for each service. Connect servers also accept gRPC and gRPC-Web requests, so you can call them with grpcurl or a standard gRPC client. It depends on the message types from protoc-gen-go, so run both.

Common usage

Terminal

go install connectrpc.com/connect/cmd/protoc-gen-connect-go@latest

# buf.gen.yaml (v2)
# plugins:
#   - remote: buf.build/protocolbuffers/go
#     out: gen
#     opt: paths=source_relative
#   - local: protoc-gen-connect-go
#     out: gen
#     opt: paths=source_relative

buf generate

Flags and options

Item	What it does
--connect-go_out=<dir>	Invoke the plugin under raw protoc
--connect-go_opt=paths=source_relative	Mirror the .proto directory layout
local: protoc-gen-connect-go	Reference the plugin from buf.gen.yaml
package option	Output package is driven by the proto go_package

In CI

Run protoc-gen-connect-go together with protoc-gen-go (Connect needs the message types). Using buf generate with a local: Connect plugin and a remote: Go plugin is a common, reproducible setup. Because Connect handlers also serve gRPC, your existing grpcurl and grpc_health_probe checks keep working.

Common errors in CI

"protoc-gen-connect-go: program not found or is not executable" means the plugin was not installed or is off PATH; go install connectrpc.com/connect/cmd/protoc-gen-connect-go@<version>. A Go build error referencing missing *pb.go types means you generated Connect code without also running protoc-gen-go. Make sure the go_package option is set so the generated package path resolves.