Dapr’s gRPC Interface

Dapr and gRPC

Dapr implements both an HTTP and a gRPC API for local calls. gRPC is useful for low-latency, high performance scenarios and has language integration using the proto clients.

You can find a list of auto-generated clients .

The Dapr runtime implements a proto service that apps can communicate with via gRPC.

In addition to calling Dapr via gRPC, Dapr supports service to service calls with gRPC by acting as a proxy. See more information .

This tells Dapr to communicate with your app via gRPC over port 5005.

Kubernetes

On Kubernetes, set the following annotations in your deployment YAML:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp
  namespace: default
  labels:
    app: myapp
spec:
  replicas: 1
  selector:
    matchLabels:
      app: myapp
  template:
    metadata:
      labels:
        app: myapp
      annotations:
        dapr.io/enabled: "true"
        dapr.io/app-id: "myapp"
        dapr.io/app-protocol: "grpc"
...

The following steps show you how to create a Dapr client and call the SaveStateData operation on it:

Import the package


import (
    "context"
    "log"
    "os"
    dapr "github.com/dapr/go-sdk/client"
)

Create the client

Invoke the Save State method

// save state with the key key1
err = client.SaveState(ctx, "statestore", "key1", data)
if err != nil {
  log.Panic(err)
}
log.Println("data saved")

Hooray!

The following steps will show you how to create an app that exposes a server for Dapr to communicate with.

Import the package

package main
import (
    "context"
    "fmt"
    "log"
    "net"
    "github.com/golang/protobuf/ptypes/empty"
    commonv1pb "github.com/dapr/go-sdk/dapr/proto/common/v1"
    pb "github.com/dapr/go-sdk/dapr/proto/runtime/v1"
    "google.golang.org/grpc"
)

Implement the interface

Create the server

func main() {
    // create listener
    lis, err := net.Listen("tcp", ":50001")
    if err != nil {
        log.Fatalf("failed to listen: %v", err)
    }
    // create grpc server
    s := grpc.NewServer()
    pb.RegisterAppCallbackServer(s, &server{})
    fmt.Println("Client starting...")
    // and start...
    if err := s.Serve(lis); err != nil {
        log.Fatalf("failed to serve: %v", err)
    }
}

This creates a gRPC server for your app on port 4000.

Run your app

To run locally, use the Dapr CLI:

dapr run --app-id goapp --app-port 4000 --app-protocol grpc go run main.go

On Kubernetes, set the required dapr.io/app-protocol: "grpc" and annotations in your pod spec template as mentioned above.

gRPC interface

Dapr’s gRPC Interface

Dapr and gRPC

Kubernetes