Native gRPC Compatibility

This guide explains how to make your Go Micro services compatible with native gRPC clients like grpcurl, grpcui, or clients generated by the standard protoc gRPC plugin in any language.

A complete, runnable version of everything in this guide lives in examples/grpc.

Understanding Transport vs Server

Go Micro has two different gRPC-related concepts that are often confused:

gRPC Transport (`go-micro.dev/v6/transport/grpc`)

The gRPC transport uses the gRPC protocol as a communication layer, similar to how you might use NATS, RabbitMQ, or HTTP. It does not guarantee compatibility with native gRPC clients.

// This uses gRPC as transport but is NOT compatible with native gRPC clients
import "go-micro.dev/v6/transport/grpc"

t := grpc.NewTransport()
service := micro.NewService("helloworld",
    micro.Transport(t),
)

When using the gRPC transport:

Communication between Go Micro services works fine
Native gRPC clients (grpcurl, etc.) will fail with "Unimplemented" errors
The protocol is used like a message bus, not as a standard gRPC server

gRPC Server/Client (`go-micro.dev/v6/server/grpc` and `go-micro.dev/v6/client/grpc`)

The gRPC server and client provide native gRPC compatibility. These implement a proper gRPC server that any gRPC client can communicate with.

// This IS compatible with native gRPC clients
import (
    "go-micro.dev/v6"
    grpcServer "go-micro.dev/v6/server/grpc"
    grpcClient "go-micro.dev/v6/client/grpc"
)

service := micro.NewService("helloworld",
    micro.Server(grpcServer.NewServer()),
    micro.Client(grpcClient.NewClient()),
)

When to Use Which

Use Case	Solution
Need native gRPC client compatibility	Use gRPC server/client
Need to call service with `grpcurl`	Use gRPC server
Want `grpcurl`/`grpcui` to auto-discover methods (no `-proto` flag)	Add `grpcServer.Reflection()`
Need polyglot gRPC clients (Python, Java, etc.)	Use gRPC server
Only Go Micro services communicating	Either works
Want gRPC as a message protocol (like NATS)	Use gRPC transport

Complete Example: Native gRPC Compatible Service

Proto Definition

protobuf

syntax = "proto3";

package helloworld;
option go_package = "./proto;helloworld";

service Say {
    rpc Hello(Request) returns (Response) {}
}

message Request {
    string name = 1;
}

message Response {
    string message = 1;
}

Generate Code

bash

# Install protoc-gen-micro and the native gRPC plugin
go install go-micro.dev/v6/cmd/protoc-gen-micro@latest
go install google.golang.org/protobuf/cmd/protoc-gen-go@latest
go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@latest

# Generate Go code (--go-grpc_out is needed for a native gRPC client)
protoc --proto_path=. \
    --go_out=. --go_opt=paths=source_relative \
    --go-grpc_out=. --go-grpc_opt=paths=source_relative \
    --micro_out=. --micro_opt=paths=source_relative \
    proto/helloworld.proto

Server Implementation

package main

import (
    "context"
    "log"

    "go-micro.dev/v6"
    "go-micro.dev/v6/server"
    grpcServer "go-micro.dev/v6/server/grpc"
    pb "example.com/helloworld/proto"
)

type Say struct{}

func (s *Say) Hello(ctx context.Context, req *pb.Request, rsp *pb.Response) error {
    rsp.Message = "Hello " + req.Name
    return nil
}

func main() {
    // Create service with gRPC server for native gRPC compatibility.
    // The service name and address must be set on the gRPC server itself:
    // micro.NewService's Name/Address options are discarded when the default
    // server is swapped out.
    service := micro.NewService("helloworld",
        micro.Server(grpcServer.NewServer(
            server.Name("helloworld"),
            server.Address(":8080"),
            // Enable gRPC reflection so grpcurl and friends can discover
            // the service without local proto files.
            grpcServer.Reflection(),
        )),
    )

    service.Init()

    // Register handler
    pb.RegisterSayHandler(service.Server(), &Say{})

    // Run service
    if err := service.Run(); err != nil {
        log.Fatal(err)
    }
}

Client Implementation (Go Micro)

package main

import (
    "context"
    "fmt"
    "log"

    "go-micro.dev/v6"
    grpcClient "go-micro.dev/v6/client/grpc"
    pb "example.com/helloworld/proto"
)

func main() {
    // Create service with gRPC client
    service := micro.NewService("helloworld.client",
        micro.Client(grpcClient.NewClient()),
    )
    service.Init()

    // Create client - use the service name "helloworld" (not the proto package name)
    // Go Micro uses this name for registry lookup, which may differ from the package name
    sayService := pb.NewSayService("helloworld", service.Client())

    // Call service
    rsp, err := sayService.Hello(context.Background(), &pb.Request{Name: "Alice"})
    if err != nil {
        log.Fatal(err)
    }

    fmt.Println(rsp.Message) // Output: Hello Alice
}

Testing with grpcurl

Once your service is running with the gRPC server and grpcServer.Reflection(), you can use grpcurl. Reflection lets grpcurl discover the service and its methods on the wire, so no local proto file is needed:

bash

# List available services
grpcurl -plaintext localhost:8080 list

# Describe the service
grpcurl -plaintext localhost:8080 describe helloworld.Say

# Call the Hello method
grpcurl -plaintext \
    -d '{"name":"Alice"}' \
    localhost:8080 helloworld.Say.Hello

Without reflection, fall back to the -proto flag pointing at the .proto file.

Using Both gRPC Server and Client Together

For full native gRPC compatibility (both inbound and outbound), use both:

package main

import (
    "go-micro.dev/v6"
    "go-micro.dev/v6/server"
    grpcClient "go-micro.dev/v6/client/grpc"
    grpcServer "go-micro.dev/v6/server/grpc"
)

func main() {
    service := micro.NewService("helloworld",
        micro.Server(grpcServer.NewServer(
            server.Name("helloworld"),
            server.Address(":8080"),
            grpcServer.Reflection(),
        )),
        micro.Client(grpcClient.NewClient()),
    )

    service.Init()
    // ... register handlers
    service.Run()
}

Common Errors

"unknown service" Error with grpcurl

If you see this error:

ERROR:
  Code: Unimplemented
  Message: unknown service helloworld.Say

Cause: You're using the gRPC transport instead of the gRPC server.

Solution: Change from:

// Wrong - uses transport
t := grpc.NewTransport()
service := micro.NewService("helloworld",
    micro.Transport(t),
)

To:

// Correct - uses server
import grpcServer "go-micro.dev/v6/server/grpc"

service := micro.NewService("helloworld",
    micro.Server(grpcServer.NewServer()),
)

`grpcurl list` fails with "reflection service is not implemented"

If you see:

ERROR:
  Code: Unimplemented
  Message: unknown service grpc.reflection.v1alpha.ServerReflection

Cause: The gRPC server was created without the Reflection() option.

Solution: Add grpcServer.Reflection() to the server options so gRPC's reflection service is registered.

Service Name Not Set on the gRPC Server

Symptom: The service registers under the default name, or handlers can't be found when a client looks up the name passed to micro.NewService.

Cause: The service name passed to micro.NewService("helloworld", ...) is discarded when you swap in a gRPC server via micro.Server(...).

Solution: Set the name on the gRPC server itself:

service := micro.NewService("helloworld",
    micro.Server(grpcServer.NewServer(
        server.Name("helloworld"),
    )),
)

Import Path Confusion

Note the different import paths:

// Transport (NOT native gRPC compatible)
import "go-micro.dev/v6/transport/grpc"

// Server (native gRPC compatible)
import "go-micro.dev/v6/server/grpc"

// Client (native gRPC compatible)
import "go-micro.dev/v6/client/grpc"

Service Name vs Package Name

When creating a client to call another service, use the service name passed to micro.NewService, not the proto package name:

// If the server was started with micro.NewService("helloworld", ...)
sayService := pb.NewSayService("helloworld", service.Client())  // Use service name

// NOT the package name from the proto file
// sayService := pb.NewSayService("helloworld.Say", service.Client())  // Wrong!

Go Micro uses the service name for registry lookup, which may differ from the proto package name.

Environment Variable Configuration

You can also configure the server and client via environment variables:

bash

# Use gRPC server
MICRO_SERVER=grpc go run main.go

# Use gRPC client
MICRO_CLIENT=grpc go run main.go

Summary

Component	Import Path	Native gRPC Compatible
Transport	`go-micro.dev/v6/transport/grpc`	❌ No
Server	`go-micro.dev/v6/server/grpc`	✅ Yes
Client	`go-micro.dev/v6/client/grpc`	✅ Yes

For native gRPC compatibility with tools like grpcurl or polyglot clients, always use the gRPC server and client packages, not the transport.

Transport - Understanding transports in Go Micro
Plugins - Available plugins including gRPC
Migration from gRPC - Migrating existing gRPC services

Understanding Transport vs Server

gRPC Transport (go-micro.dev/v6/transport/grpc)

gRPC Server/Client (go-micro.dev/v6/server/grpc and go-micro.dev/v6/client/grpc)

When to Use Which

Complete Example: Native gRPC Compatible Service

Proto Definition

Generate Code

Server Implementation

Client Implementation (Go Micro)

Testing with grpcurl

Using Both gRPC Server and Client Together

Common Errors

"unknown service" Error with grpcurl

grpcurl list fails with "reflection service is not implemented"

Service Name Not Set on the gRPC Server

Import Path Confusion

Service Name vs Package Name

Environment Variable Configuration

Summary

Related Documentation

gRPC Transport (`go-micro.dev/v6/transport/grpc`)

gRPC Server/Client (`go-micro.dev/v6/server/grpc` and `go-micro.dev/v6/client/grpc`)

`grpcurl list` fails with "reflection service is not implemented"