A collection of Ruby interceptors (middlewares) for gRPC servers and clients.

Heavily inspired by grpc-ecosystem/go-grpc-middleware. The motivation is to have a unified behavior of gRPC services and integrated telemetry data (logging, tracing and metrics) regardless of the used language.

• Server
  • Error handling
  • Logging
  • StatsD metrics
  • OpenTelemetry tracing
• Client
  • Logging
  • OpenTelemetry tracing
  • Retry mechanism

The order of interceptors matters. Considering all server interceptors, the correct way of installation is:

WIP

When the LOG_LEVEL env variable is set to INFO then the server logs out.

When the LOG_LEVEL env variable is set to DEBUG then the server additionally adds the request to the log message. (Note, adding the response is currently blocked by this gRPC issue.)

GRPC::RpcServer.new(
  interceptors: [
    GrpcInterceptors::Server::StatsDMetrics.new
  ]
)

The server emits a histogram metric called grpc_latency_seconds with the following tags:

• grpc_method representing the called method
• grpc_service representing the service
• grpc_type representing the gRPC kind of method

# https://github.com/grpc/grpc/blob/v1.62.0/src/ruby/lib/grpc/generic/rpc_server.rb#L43C9-L43C21
server.instance_variable_get(:@pool).jobs_waiting

GRPC::RpcServer.new(
  interceptors: [
    GrpcInterceptors::Server::OpenTelemetryTracingInstrument.new
  ]
)

GRPC::RpcServer.new(
  interceptors: [
    GrpcInterceptors::Client::OpenTelemetryTracingInstrument.new
  ]
)

Integration tests require some infrastructure to mimic gRPC client and server. For this purpose, there's a simple service definition in the test/integration/support/ping.proto. To re-generate *_pb.rb files run bundle exec rake proto:generate.

bundle exec rake build
bundle exec rake release