feat: add grpc export (#2379)

Co-authored-by: Gene Wu <gene.wu@cabital.com>

core/trace/agent.go

@@ -3,12 +3,14 @@ package trace
 import (
 	"context"
 	"fmt"
+	"google.golang.org/grpc"
 	"sync"
 
 	"github.com/zeromicro/go-zero/core/lang"
 	"github.com/zeromicro/go-zero/core/logx"
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/exporters/jaeger"
+	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc"
 	"go.opentelemetry.io/otel/exporters/zipkin"
 	"go.opentelemetry.io/otel/sdk/resource"
 	sdktrace "go.opentelemetry.io/otel/sdk/trace"
@@ -18,6 +20,7 @@ import (
 const (
 	kindJaeger = "jaeger"
 	kindZipkin = "zipkin"
+	kindGrpc   = "grpc"
 )
 
 var (
@@ -56,6 +59,8 @@ func createExporter(c Config) (sdktrace.SpanExporter, error) {
 		return jaeger.New(jaeger.WithCollectorEndpoint(jaeger.WithEndpoint(c.Endpoint)))
 	case kindZipkin:
 		return zipkin.New(c.Endpoint)
+	case kindGrpc:
+		return otlptracegrpc.NewUnstarted(otlptracegrpc.WithInsecure(), otlptracegrpc.WithEndpoint(c.Endpoint), otlptracegrpc.WithDialOption(grpc.WithBlock())), nil
 	default:
 		return nil, fmt.Errorf("unknown exporter: %s", c.Batcher)
 	}

core/trace/agent_test.go

@@ -33,18 +33,24 @@ func TestStartAgent(t *testing.T) {
 		Endpoint: endpoint3,
 		Batcher:  "otlp",
 	}
+	c5 := Config{
+		Name:     "grpc",
+		Endpoint: endpoint3,
+		Batcher:  "grpc",
+	}
 
 	StartAgent(c1)
 	StartAgent(c1)
 	StartAgent(c2)
 	StartAgent(c3)
 	StartAgent(c4)
+	StartAgent(c5)
 
 	lock.Lock()
 	defer lock.Unlock()
 
 	// because remotehost cannot be resolved
-	assert.Equal(t, 2, len(agents))
+	assert.Equal(t, 3, len(agents))
 	_, ok := agents[""]
 	assert.True(t, ok)
 	_, ok = agents[endpoint1]

core/trace/config.go

@@ -8,5 +8,5 @@ type Config struct {
 	Name     string  `json:",optional"`
 	Endpoint string  `json:",optional"`
 	Sampler  float64 `json:",default=1.0"`
-	Batcher  string  `json:",default=jaeger,options=jaeger|zipkin"`
+	Batcher  string  `json:",default=jaeger,options=jaeger|zipkin|grpc"`
 }