--- name: grpc-3df73b052969 description: >- Build high-performance RPC services with gRPC and Protocol Buffers. Use when a user asks to create gRPC services, define protobuf schemas, implement streaming RPCs, build microservice communication, set up service-to-service calls, implement bidirectional streaming, add interceptors/middleware to gRPC, generate client stubs, handle gRPC errors, implement health checks, configure load balancing, or build gRPC-Web for browser clients. Covers unary, server/client/bidirectional streaming, interceptors, deadlines, metadata, reflection, and production patterns. license: Apache-2.0 compatibility: 'Node.js 18+, Python 3.9+, or a currently supported Go release (grpc, protobuf)' metadata: author: terminal-skills version: 1.1.0 category: development tags: "grpc, rpc, protobuf, microservices, streaming" --- # gRPC ## Overview Build high-performance, strongly-typed RPC services using gRPC and Protocol Buffers. gRPC uses HTTP/2 for transport, protobuf for serialization (compact binary format, typically much smaller and faster to parse than JSON), and generates client/server code in 12+ languages. Ideal for microservice communication, real-time streaming, and performance-critical APIs. ## Instructions ### Step 1: Install Tools ```bash # Protocol Buffer Compiler brew install protobuf # macOS apt install -y protobuf-compiler # Ubuntu/Debian # Node.js npm install @grpc/grpc-js @grpc/proto-loader npm install @grpc/reflection grpc-health-check # optional: reflection + standard health service # Python pip install grpcio grpcio-tools grpcio-reflection grpcio-health-checking # Go go install google.golang.org/protobuf/cmd/protoc-gen-go@latest go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@latest # make sure $(go env GOPATH)/bin is on PATH, or protoc cannot find the plugins ``` Prefer [Buf](https://buf.build) (`buf generate`, `buf lint`, `buf breaking`) when a repo has many protos: it replaces long protoc command lines and catches breaking changes in CI. ### Step 2: Define Protocol Buffers ```protobuf // proto/user_service.proto syntax = "proto3"; package userservice.v1; import "google/protobuf/timestamp.proto"; import "google/protobuf/empty.proto"; import "google/protobuf/field_mask.proto"; service UserService { rpc GetUser(GetUserRequest) returns (User); rpc CreateUser(CreateUserRequest) returns (User); rpc UpdateUser(UpdateUserRequest) returns (User); rpc DeleteUser(DeleteUserRequest) returns (google.protobuf.Empty); rpc ListUsers(ListUsersRequest) returns (ListUsersResponse); rpc WatchUser(WatchUserRequest) returns (stream UserEvent); // Server streaming rpc BatchCreateUsers(stream CreateUserRequest) returns (BatchCreateUsersResponse); // Client streaming rpc Chat(stream ChatMessage) returns (stream ChatMessage); // Bidirectional } message User { string id = 1; string email = 2; string name = 3; Role role = 5; google.protobuf.Timestamp created_at = 6; } enum Role { ROLE_UNSPECIFIED = 0; ROLE_USER = 1; ROLE_ADMIN = 2; } message GetUserRequest { string id = 1; } message CreateUserRequest { string email = 1; string name = 2; string password = 3; } message UpdateUserRequest { string id = 1; string name = 2; google.protobuf.FieldMask update_mask = 4; } message DeleteUserRequest { string id = 1; } message ListUsersRequest { int32 page_size = 1; string page_token = 2; string filter = 3; } message ListUsersResponse { repeated User users = 1; string next_page_token = 2; int32 total_count = 3; } message WatchUserRequest { string id = 1; } message UserEvent { enum EventType { EVENT_TYPE_UNSPECIFIED = 0; EVENT_TYPE_UPDATED = 1; EVENT_TYPE_DELETED = 2; } EventType type = 1; User user = 2; google.protobuf.Timestamp timestamp = 3; } message BatchCreateUsersResponse { int32 created_count = 1; repeated string failed_emails = 2; } message ChatMessage { string sender_id = 1; string text = 2; google.protobuf.Timestamp timestamp = 3; } ``` Protobuf rules: field numbers are forever (never reuse), use `UNSPECIFIED = 0` for enums, `repeated` for lists, `FieldMask` for partial updates, `Timestamp` for dates, version via package name (`userservice.v1`). ### Step 3: Generate Code ```bash # Python python -m grpc_tools.protoc -I proto --python_out=gen --grpc_python_out=gen --pyi_out=gen proto/user_service.proto # Go protoc -I proto --go_out=gen --go_opt=paths=source_relative --go-grpc_out=gen --go-grpc_opt=paths=source_relative proto/user_service.proto ``` Node.js can load protos dynamically (no codegen needed): ```javascript const grpc = require('@grpc/grpc-js'); const protoLoader = require('@grpc/proto-loader'); const packageDef = protoLoader.loadSync('proto/user_service.proto', { keepCase: true, longs: String, enums: String, defaults: true, oneofs: true, }); const proto = grpc.loadPackageDefinition(packageDef).userservice.v1; ``` ### Step 4: Server Implementation (Node.js) ```javascript const userService = { GetUser(call, callback) { const user = users.get(call.request.id); if (!user) return callback({ code: grpc.status.NOT_FOUND, message: `User ${call.request.id} not found` }); callback(null, user); }, CreateUser(call, callback) { const { email, name } = call.request; const user = { id: crypto.randomUUID(), email, name, role: 'ROLE_USER', created_at: { seconds: Date.now() / 1000 } }; users.set(user.id, user); callback(null, user); }, WatchUser(call) { // Server streaming const interval = setInterval(() => { const user = users.get(call.request.id); if (user) call.write({ type: 'EVENT_TYPE_UPDATED', user, timestamp: { seconds: Date.now() / 1000 } }); }, 5000); call.on('cancelled', () => clearInterval(interval)); }, BatchCreateUsers(call, callback) { // Client streaming let created = 0; const failed = []; call.on('data', (req) => { users.set(crypto.randomUUID(), { email: req.email, name: req.name }); created++; }); call.on('end', () => callback(null, { created_count: created, failed_emails: failed })); }, Chat(call) { // Bidirectional streaming call.on('data', (msg) => call.write({ sender_id: 'server', text: `Received: ${msg.text}` })); call.on('end', () => call.end()); }, }; const server = new grpc.Server(); server.addService(proto.UserService.service, userService); // grpc-js 1.10+ starts serving once bound; server.start() is deprecated and not needed server.bindAsync('0.0.0.0:50051', grpc.ServerCredentials.createInsecure(), (err, port) => { if (err) throw err; console.log(`gRPC listening on ${port}`); }); ``` ### Step 5: Client Implementation ```javascript const client = new proto.UserService('localhost:50051', grpc.credentials.createInsecure()); // Unary with deadline const deadline = new Date(); deadline.setSeconds(deadline.getSeconds() + 5); client.GetUser({ id: '123' }, { deadline }, (err, user) => { if (!err) console.log(user); }); // Server streaming const stream = client.WatchUser({ id: '123' }); stream.on('data', (event) => console.log('Event:', event)); // Client streaming const batch = client.BatchCreateUsers((err, resp) => console.log(`Created: ${resp.created_count}`)); batch.write({ email: 'alice.moreau@northwind.dev', name: 'Alice' }); batch.write({ email: 'bob.keller@northwind.dev', name: 'Bob' }); batch.end(); ``` ### Step 6: Error Handling ``` gRPC Status Codes: NOT_FOUND (5) — Resource missing (like HTTP 404) INVALID_ARGUMENT (3) — Bad input (like HTTP 400) UNAUTHENTICATED (16) — Not authenticated (like HTTP 401) PERMISSION_DENIED (7) — Forbidden (like HTTP 403) ALREADY_EXISTS (6) — Duplicate (like HTTP 409) RESOURCE_EXHAUSTED (8) — Rate limited (like HTTP 429) DEADLINE_EXCEEDED (4) — Timeout UNAVAILABLE (14) — Service down (like HTTP 503) INTERNAL (13) — Server error (like HTTP 500) ``` ### Step 7: Testing with grpcurl ```bash brew install grpcurl grpcurl -plaintext localhost:50051 list grpcurl -plaintext -d '{"email": "alice.moreau@northwind.dev", "name": "Alice"}' \ localhost:50051 userservice.v1.UserService/CreateUser ``` ## Examples ### Example 1: Build a user microservice with gRPC **User prompt:** "Create a gRPC user service in Node.js with CRUD operations and server streaming for live user updates." The agent will: 1. Create `proto/user_service.proto` with `UserService` defining `GetUser`, `CreateUser`, `ListUsers` (unary RPCs) and `WatchUser` (server streaming) 2. Load the proto dynamically using `@grpc/proto-loader` 3. Implement handlers for each RPC method, using proper status codes (`NOT_FOUND`, `ALREADY_EXISTS`) 4. Start the server on port 50051 and verify with `grpcurl -plaintext localhost:50051 list` ### Example 2: Add batch user import with client streaming **User prompt:** "Add a batch import endpoint to the user service that accepts a stream of user records from a CSV file and returns a summary of created/failed records." The agent will: 1. Add a `BatchCreateUsers(stream CreateUserRequest) returns (BatchCreateUsersResponse)` RPC to the proto file 2. Implement the server handler with `call.on('data')` to process each streamed request, tracking created count and failed emails 3. Build a client script that reads the CSV, streams each row as a `CreateUserRequest`, and calls `batch.end()` when done 4. Return the `BatchCreateUsersResponse` with `created_count` and `failed_emails` array ## Guidelines 1. **Proto design is your API contract** — review it as carefully as database schemas 2. **Never change field numbers** — add new fields, deprecate old ones with `reserved` 3. **Use `FieldMask` for updates** — distinguishes "not sent" from "set to empty" 4. **Always set deadlines** — unbound calls leak resources; 5-30s for most RPCs 5. **Enable reflection in dev only** — `@grpc/reflection` (Node), `grpcio-reflection` (Python) make grpcurl/grpcui work without the .proto; do not expose it publicly in production 11. **Use TLS outside localhost** — `createInsecure()` is for local development; use `grpc.ServerCredentials.createSsl(...)` or terminate TLS at the mesh 6. **Health checks on every service** — standard gRPC health protocol for load balancers 7. **Interceptors for cross-cutting concerns** — auth, logging, metrics, tracing 8. **Use streaming sparingly** — unary RPCs are simpler to debug and load-balance 9. **Version via package name** — `userservice.v1`, `userservice.v2` 10. **Keep messages small** — gRPC default max is 4MB; large payloads should be chunked --- Source attribution: terminal-skills Original project: https://github.com/TerminalSkills/skills/blob/8a9852d489f274538be9bf1c9121aeb403750b1c/skills/grpc/SKILL.md License: Apache-2.0 License information: https://www.apache.org/licenses/LICENSE-2.0 Original upstream instructions; downloaded from Dave AI. ## Upstream license notice Apache License Version 2.0, January 2004 http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. 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See the License for the specific language governing permissions and limitations under the License. # Dave AI resource metadata Creator / publisher: terminal-skills Original project: https://github.com/TerminalSkills/skills/blob/8a9852d489f274538be9bf1c9121aeb403750b1c/skills/grpc/SKILL.md Attribution basis: Source repository record Fields of work: Development & Engineering, Product Management Roles: Backend Developer, ML / AI Engineer, Data Engineer, DevOps / SRE, Product Manager Specialties: Backend, API Tools: Protobuf, Grpc Country applicability: Country not specified Classification basis: Source category, role and specialization labels Instruction SHA-256: c90ecb1268430e8d47a24aa1f53cecf6cd238c2af8b40aab7108a88eac2a2a2e