Grpc

Introduction

Grpc module can be operated by facades.Grpc(). Goravel provides an elegant way to build and consume gRPC services, supporting both server and client sides.

Configuration

In the config/grpc.go file, you can configure the Grpc module, where grpc.host configures the domain name of the server, and grpc.clients configures the clients which will connect to gRPC services.

Transport Credentials

By default, gRPC clients use insecure transport credentials and the gRPC server listens without TLS. You can register credentials.TransportCredentials during application bootstrap when your services require TLS or mTLS.

Server Credentials

Register server credentials before the gRPC server is created:

import "google.golang.org/grpc/credentials"

func Boot() contractsfoundation.Application {
  return foundation.Setup().
    WithGrpcServerCredentials(func() credentials.TransportCredentials {
      creds, err := credentials.NewServerTLSFromFile(
        "storage/certs/server.crt",
        "storage/certs/server.key",
      )
      if err != nil {
        panic(err)
      }

      return creds
    }).
    Create()
}

Client Credentials

Register client credential groups in bootstrap/app.go, then reference the group name in config/grpc.go with grpc.clients.<name>.credentials:

import "google.golang.org/grpc/credentials"

func Boot() contractsfoundation.Application {
  return foundation.Setup().
    WithGrpcClientCredentials(func() map[string]credentials.TransportCredentials {
      userCreds, err := credentials.NewClientTLSFromFile(
        "storage/certs/ca.crt",
        "user.example.com",
      )
      if err != nil {
        panic(err)
      }

      return map[string]credentials.TransportCredentials{
        "user": userCreds,
      }
    }).
    Create()
}

"servers": map[string]any{
  "user": map[string]any{
    "host":           config.Env("GRPC_USER_HOST", ""),
    "port":           config.Env("GRPC_USER_PORT", ""),
    "credentials":    "user",
    "interceptors":   []string{},
    "stats_handlers": []string{},
  },
},

If a client has no credentials value, Goravel uses insecure credentials for backward compatibility. If the configured group is not registered, Goravel logs a warning and falls back to insecure credentials. For mTLS, return credentials created with credentials.NewTLS and a tls.Config that includes the required client certificates or trusted CA pools.

Controllers

Controllers can be defined in the app/grpc/controllers directory.

package controllers

import (
  "context"
  "net/http"

  proto "github.com/goravel/example-proto"
)

type UserController struct {}

func NewUserController() *UserController {
  return &UserController{}
}

func (r *UserController) GetUser(ctx context.Context, req *proto.UserRequest) (*proto.UserResponse, error) {
  return &proto.UserResponse{
    Code: http.StatusOK,
    Data: &proto.User{
      Id:    1,
      Name:  "Goravel",
      Token: req.GetToken(),
    },
  }, nil
}

Define routing

All routing files can be defined in the routes directory, such as routes/grpc.go.

package routes

import (
  proto "github.com/goravel/example-proto"

  "goravel/app/facades"
  "goravel/app/grpc/controllers"
)

func Grpc() {
  proto.RegisterUserServiceServer(facades.Grpc().Server(), controllers.NewUserController())
}

Register routing

Register routing in the bootstrap/app.go::WithRouting function after routing was defined.

func Boot() contractsfoundation.Application {
	return foundation.Setup().
		WithRouting(func() {
      routes.Grpc()
    }).
		WithConfig(config.Boot).
		Create()
}

Interceptor

Interceptors provide a way to intercept and modify gRPC requests and responses. They can be used for logging, authentication, metrics, and more.

Define Interceptors

Interceptors can be defined in the app/grpc/interceptors folder.

Server Interceptor Example:

package interceptors

import (
  "context"

  "google.golang.org/grpc"
)

func TestServer(ctx context.Context, req any, info *grpc.UnaryServerInfo, handler grpc.UnaryHandler) (resp any, err error) {
  // Add your logic before the request is handled
  // For example: logging, authentication, etc.
  
  return handler(ctx, req)
}

Client Interceptor Example:

package interceptors

import (
  "context"

  "google.golang.org/grpc"
)

func TestClient(ctx context.Context, method string, req, reply any, cc *grpc.ClientConn, invoker grpc.UnaryInvoker, opts ...grpc.CallOption) error {
  // Add your logic before the request is sent
  // For example: logging, adding metadata, etc.
  
  return invoker(ctx, method, req, reply, cc, opts...)
}

Register Interceptors

Register interceptors in the bootstrap/app.go file using the WithGrpcServerInterceptors, WithGrpcClientInterceptors, WithGrpcServerStatsHandlers, and WithGrpcClientStatsHandlers functions.

import (
  "github.com/goravel/framework/contracts/foundation"
  "google.golang.org/grpc"
  "google.golang.org/grpc/stats"
  
  "goravel/app/grpc/interceptors"
)

func Boot() foundation.Application {
  return foundation.Setup().
    WithGrpcServerInterceptors(func() []grpc.UnaryServerInterceptor {
      return []grpc.UnaryServerInterceptor{
        interceptors.TestServer,
      }
    }).
    WithGrpcClientInterceptors(func() map[string][]grpc.UnaryClientInterceptor {
      return map[string][]grpc.UnaryClientInterceptor{
        "default": {
          interceptors.TestClient,
        },
      }
    }).
    WithGrpcServerStatsHandlers(func() []stats.Handler {
      return []stats.Handler{}
    }).
    WithGrpcClientStatsHandlers(func() map[string][]stats.Handler {
      return map[string][]stats.Handler{}
    }).
    Create()
}

Apply Interceptors to Clients

The default in the example above is a group name that can be applied to the configuration item grpc.clients.interceptors. In this way, the client will use all interceptors under the group.

package config

import (
  "goravel/app/facades"
)

func init() {
  config := facades.Config()
  config.Add("grpc", map[string]any{
    "host": config.Env("GRPC_HOST", ""),
    "port": config.Env("GRPC_PORT", ""),
    
    "clients": map[string]any{
      "user": map[string]any{
        "host":           config.Env("GRPC_USER_HOST", ""),
        "port":           config.Env("GRPC_USER_PORT", ""),
        "interceptors":   []string{"default"},
        "stats_handlers": []string{},
      },
    },
  })
}

Stats Handlers

Stats handlers are gRPC's mechanism for collecting metrics and monitoring RPC calls. They provide hooks into the lifecycle of both client and server RPCs, making them ideal for:

• Request/response monitoring
• Performance metrics collection
• Custom observability integrations
• Logging and debugging

Register Stats Handlers

Stats handlers can be registered in the bootstrap/app.go file using the WithGrpcServerStatsHandlers and WithGrpcClientStatsHandlers functions.

Server Stats Handler Example:

package stats

import (
  "context"
  
  "google.golang.org/grpc/stats"
)

type ServerStatsHandler struct{}

func NewServerStatsHandler() stats.Handler {
  return &ServerStatsHandler{}
}

func (h *ServerStatsHandler) TagRPC(ctx context.Context, info *stats.RPCTagInfo) context.Context {
  // Called at the beginning of each RPC
  return ctx
}

func (h *ServerStatsHandler) HandleRPC(ctx context.Context, s stats.RPCStats) {
  // Called for each RPC event
}

func (h *ServerStatsHandler) TagConn(ctx context.Context, info *stats.ConnTagInfo) context.Context {
  // Called when a connection is established
  return ctx
}

func (h *ServerStatsHandler) HandleConn(ctx context.Context, s stats.ConnStats) {
  // Called for connection events
}

Client Stats Handler Example:

package stats

import (
  "context"
  
  "google.golang.org/grpc/stats"
)

type ClientStatsHandler struct{}

func NewClientStatsHandler() stats.Handler {
  return &ClientStatsHandler{}
}

func (h *ClientStatsHandler) TagRPC(ctx context.Context, info *stats.RPCTagInfo) context.Context {
  return ctx
}

func (h *ClientStatsHandler) HandleRPC(ctx context.Context, s stats.RPCStats) {
  // Handle RPC events like Begin, End, InPayload, OutPayload
}

func (h *ClientStatsHandler) TagConn(ctx context.Context, info *stats.ConnTagInfo) context.Context {
  return ctx
}

func (h *ClientStatsHandler) HandleConn(ctx context.Context, s stats.ConnStats) {
  // Handle connection events
}

Register in Bootstrap

Register your stats handlers in bootstrap/app.go:

import (
  "google.golang.org/grpc/stats"
  
  grpcstats "goravel/app/grpc/stats"
)

func Boot() foundation.Application {
  return foundation.Setup().
    WithGrpcServerStatsHandlers(func() []stats.Handler {
      return []stats.Handler{
        grpcstats.NewServerStatsHandler(),
      }
    }).
    WithGrpcClientStatsHandlers(func() map[string][]stats.Handler {
      return map[string][]stats.Handler{
        "user": {
          grpcstats.NewClientStatsHandler(),
        },
      }
    }).
    Create()
}

Apply Stats Handlers to Clients

The group name (e.g., "user") must be referenced in your config/grpc.go file under the client's stats_handlers array:

package config

import (
  "goravel/app/facades"
)

func init() {
  config := facades.Config()
  config.Add("grpc", map[string]any{
    "host": config.Env("GRPC_HOST", ""),
    "port": config.Env("GRPC_PORT", ""),
    
    "clients": map[string]any{
      "user": map[string]any{
        "host":           config.Env("GRPC_USER_HOST", ""),
        "port":           config.Env("GRPC_USER_PORT", ""),
        "interceptors":   []string{"default"},
        "stats_handlers": []string{"user"}, // Apply "user" stats handler group
      },
    },
  })
}

gRPC Client

Goravel provides an easy way to create gRPC clients to consume gRPC services.

Connect to gRPC Server

You can connect to a gRPC server using the facades.Grpc().Connect() method. The connection name should match the key defined in config/grpc.go.

package controllers

import (
  "fmt"

  proto "github.com/goravel/example-proto"
  "github.com/goravel/framework/contracts/http"

  "goravel/app/facades"
)

type GrpcController struct {
  userService proto.UserServiceClient
}

func NewGrpcController() *GrpcController {
  // The initialization process can be moved to app/services/*.go
  client, err := facades.Grpc().Connect("user")
  if err != nil {
    facades.Log().Error(fmt.Sprintf("failed to connect to user server: %+v", err))
  }

  return &GrpcController{
    userService: proto.NewUserServiceClient(client),
  }
}

func (r *GrpcController) User(ctx http.Context) http.Response {
  resp, err := r.userService.GetUser(ctx, &proto.UserRequest{
    Token: ctx.Request().Input("token"),
  })
  if err != nil {
    return ctx.Response().String(http.StatusInternalServerError, fmt.Sprintf("call UserService.GetUser err: %+v", err))
  }
  if resp.Code != http.StatusOK {
    return ctx.Response().String(http.StatusInternalServerError, fmt.Sprintf("user service returns error, code: %d, message: %s", resp.Code, resp.Message))
  }

  return ctx.Response().Success().Json(resp.GetData())
}