golang-grpc
Provides gRPC usage guidelines, protobuf organization, and production-ready patterns for Golang microservices. Use when implementing, reviewing, or debugging gRPC servers/clients, writing proto files, setting up interceptors, handling gRPC errors with status codes, configuring TLS/mTLS, testing with bufconn, or working with streaming RPCs.
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Install
Works with every agent the skills CLI supports.
npx skills add https://github.com/samber/cc-skills-golang --skill golang-grpc- 01
Install
Run the command in your project. The CLI asks which agents to install for.
- 02
Describe the task
Ask your agent for something this skill covers. It loads golang-grpc automatically when relevant.
- 03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.
Security audits
Independent scans of the skill's instructions and bundled files.
SKILL.md
The instructions your agent reads when the skill is triggered.
Persona: You are a Go distributed systems engineer. You design gRPC services for correctness and operability — proper status codes, deadlines, interceptors, and graceful shutdown matter as much as the happy path.
Modes:
- Build mode — implementing a new gRPC server or client from scratch.
- Review mode — auditing existing gRPC code for correctness, security, and operability issues.
Dependencies:
- protoc:
brew install protobuf - protoc-gen-go:
go install google.golang.org/protobuf/cmd/protoc-gen-go@latest - protoc-gen-go-grpc:
go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@latest
Go gRPC Best Practices
Treat gRPC as a pure transport layer — keep it separate from business logic. The official Go implementation is google.golang.org/grpc.
This skill is not exhaustive — refer to library documentation and code examples for more information:
- For Go package docs, symbols, versions, importers, and known vulnerabilities, → See
samber/cc-skills-golang@golang-pkg-go-devskill (godig), preferred over Context7 for Go package facts. - To navigate this library's usage in your own code (definitions, call sites, diagnostics), → See
samber/cc-skills-golang@golang-goplsskill (gopls). - Context7 remains a fallback for docs not indexed on pkg.go.dev.
Quick Reference
| Concern | Package / Tool |
|---|---|
| Service definition | protoc or buf with .proto files |
| Code generation | protoc-gen-go, protoc-gen-go-grpc |
| Error handling | google.golang.org/grpc/status with codes |
| Rich error details | google.golang.org/genproto/googleapis/rpc/errdetails |
| Interceptors | grpc.ChainUnaryInterceptor, grpc.ChainStreamInterceptor |
| Middleware ecosystem | github.com/grpc-ecosystem/go-grpc-middleware |
| Testing | google.golang.org/grpc/test/bufconn |
| TLS / mTLS | google.golang.org/grpc/credentials |
| Health checks | google.golang.org/grpc/health |
Proto File Organization
Organize by domain with versioned directories (proto/user/v1/). Always use Request/Response wrapper messages — bare types like string cannot have fields added later. Generate with buf generate or protoc.
Proto & code generation reference
Server Implementation
- Implement health check service (
grpc_health_v1) — Kubernetes probes need it to determine readiness - Use interceptors for cross-cutting concerns (logging, auth, recovery) — keeps business logic clean
- Use
GracefulStop()with a timeout fallback toStop()— drains in-flight RPCs while preventing hangs - Disable reflection in production — it exposes your full API surface
srv := grpc.NewServer(
grpc.ChainUnaryInterceptor(loggingInterceptor, recoveryInterceptor),
)
pb.RegisterUserServiceServer(srv, svc)
healthpb.RegisterHealthServer(srv, health.NewServer())
go srv.Serve(lis)
// On shutdown signal:
stopped := make(chan struct{})
go func() { srv.GracefulStop(); close(stopped) }()
select {
case <-stopped:
case <-time.After(15 * time.Second):
srv.Stop()
}
Interceptor Pattern
func loggingInterceptor(ctx context.Context, req any, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (any, error) {
start := time.Now()
resp, err := handler(ctx, req)
log.Printf("method=%s duration=%s code=%s", info.FullMethod, time.Since(start), status.Code(err))
return resp, err
}
Client Implementation
- Reuse connections — gRPC multiplexes RPCs on a single HTTP/2 connection; one-per-request wastes TCP/TLS handshakes
- Set deadlines on every call (
context.WithTimeout) — without one, a slow upstream hangs goroutines indefinitely - Use
round_robinwith headless Kubernetes services viadns:///scheme - Pass metadata (auth tokens, trace IDs) via
metadata.NewOutgoingContext
conn, err := grpc.NewClient("dns:///user-service:50051",
grpc.WithTransportCredentials(creds),
grpc.WithDefaultServiceConfig(`{
"loadBalancingPolicy": "round_robin",
"methodConfig": [{
"name": [{"service": ""}],
"timeout": "5s",
"retryPolicy": {
"maxAttempts": 3,
"initialBackoff": "0.1s",
"maxBackoff": "1s",
"backoffMultiplier": 2,
"retryableStatusCodes": ["UNAVAILABLE"]
}
}]
}`),
)
client := pb.NewUserServiceClient(conn)
Error Handling
Always return gRPC errors using status.Error with a specific code — a raw error becomes codes.Unknown, telling the client nothing actionable. Clients use codes to decide retry vs fail-fast vs degrade.
| Code | When to Use |
|---|---|
InvalidArgument | Malformed input (missing field, bad format) |
NotFound | Entity does not exist |
AlreadyExists | Create failed, entity exists |
PermissionDenied | Caller lacks permission |
Unauthenticated | Missing or invalid token |
FailedPrecondition | System not in required state |
ResourceExhausted | Rate limit or quota exceeded |
Unavailable | Transient issue, safe to retry |
Internal | Unexpected bug |
DeadlineExceeded | Timeout |
// ✗ Bad — caller gets codes.Unknown, can't decide whether to retry
return nil, fmt.Errorf("user not found")
// ✓ Good — specific code lets clients act appropriately
if errors.Is(err, ErrNotFound) {
return nil, status.Errorf(codes.NotFound, "user %q not found", req.UserId)
}
return nil, status.Errorf(codes.Internal, "lookup failed: %v", err)
For field-level validation errors, attach errdetails.BadRequest via status.WithDetails.
Streaming
| Pattern | Use Case |
|---|---|
| Server streaming | Server sends a sequence (log tailing, result sets) |
| Client streaming | Client sends a sequence, server responds once (file upload, batch) |
| Bidirectional | Both send independently (chat, real-time sync) |
Prefer streaming over large single messages — avoids per-message size limits and lowers memory pressure.
func (s *server) ListUsers(req *pb.ListUsersRequest, stream pb.UserService_ListUsersServer) error {
for _, u := range users {
if err := stream.Send(u); err != nil {
return err
}
}
return nil
}
Testing
Use bufconn for in-memory connections that exercise the full gRPC stack (serialization, interceptors, metadata) without network overhead. Always test that error scenarios return the expected gRPC status codes.
Testing patterns and examples
Security
- TLS MUST be enabled in production — credentials travel in metadata
- For service-to-service auth, use mTLS or delegate to a service mesh (Istio, Linkerd)
- For user auth, implement
credentials.PerRPCCredentialsand validate tokens in an auth interceptor - Reflection SHOULD be disabled in production to prevent API discovery
Performance
| Setting | Purpose | Typical Value |
|---|---|---|
keepalive.ServerParameters.Time | Ping interval for idle connections | 30s |
keepalive.ServerParameters.Timeout | Ping ack timeout | 10s |
grpc.MaxRecvMsgSize | Override 4 MB default for large payloads | 16 MB |
| Connection pooling | Multiple conns for high-load streaming | 4 connections |
Most services do not need connection pooling — profile before adding complexity.
Common Mistakes
| Mistake | Fix |
|---|---|
Returning raw error | Becomes codes.Unknown — client can't decide whether to retry. Use status.Errorf with a specific code |
| No deadline on client calls | Slow upstream hangs indefinitely. Always context.WithTimeout |
| New connection per request | Wastes TCP/TLS handshakes. Create once, reuse — HTTP/2 multiplexes RPCs |
| Reflection enabled in production | Lets attackers enumerate every method. Enable only in dev/staging |
codes.Internal for all errors | Wrong codes break client retry logic. Unavailable triggers retry; InvalidArgument does not |
| Bare types as RPC arguments | Can't add fields to string. Wrapper messages allow backwards-compatible evolution |
| Missing health check service | Kubernetes can't determine readiness, kills pods during deployments |
| Ignoring context cancellation | Long operations continue after caller gave up. Check ctx.Err() |
Cross-References
- → See
samber/cc-skills-golang@golang-contextskill for deadline and cancellation patterns - → See
samber/cc-skills-golang@golang-error-handlingskill for gRPC error to Go error mapping - → See
samber/cc-skills-golang@golang-observabilityskill for gRPC interceptors (logging, tracing, metrics) - → See
samber/cc-skills-golang@golang-testingskill for gRPC testing with bufconn
FAQ
What does the golang-grpc skill do?
Provides gRPC usage guidelines, protobuf organization, and production-ready patterns for Golang microservices. Use when implementing, reviewing, or debugging gRPC servers/clients, writing proto files, setting up interceptors, handling gRPC errors with status codes, configuring TLS/mTLS, testing with bufconn, or working with streaming RPCs.
How do I install golang-grpc?
Run npx skills add https://github.com/samber/cc-skills-golang --skill golang-grpc in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/golang-grpc/ (personal) or .claude/skills/golang-grpc/ (project).
Which AI agents can use golang-grpc?
Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.
Is golang-grpc safe to install?
Security partners have reviewed it: Gen Agent Trust Hub passed; Socket passed; Snyk passed; ZeroLeaks passed. As with any skill, read the SKILL.md and bundled scripts before installing.
Who maintains golang-grpc?
It is published by samber in samber/cc-skills-golang. It has 39,373 recorded installs.
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