trace exporter: add new type file (#3298)

Co-authored-by: zhaikangqi <794556486@qq.com>

core/trace/agent.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"net/url"
+	"os"
 	"sync"
 
 	"github.com/zeromicro/go-zero/core/lang"
@@ -12,6 +13,7 @@ import (
 	"go.opentelemetry.io/otel/exporters/jaeger"
 	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc"
 	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp"
+	"go.opentelemetry.io/otel/exporters/stdout/stdouttrace"
 	"go.opentelemetry.io/otel/exporters/zipkin"
 	"go.opentelemetry.io/otel/sdk/resource"
 	sdktrace "go.opentelemetry.io/otel/sdk/trace"
@@ -23,6 +25,7 @@ const (
 	kindZipkin   = "zipkin"
 	kindOtlpGrpc = "otlpgrpc"
 	kindOtlpHttp = "otlphttp"
+	kindFile     = "file"
 )
 
 var (
@@ -102,6 +105,12 @@ func createExporter(c Config) (sdktrace.SpanExporter, error) {
 			context.Background(),
 			opts...,
 		)
+	case kindFile:
+		f, err := os.OpenFile(c.Endpoint, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0666)
+		if err != nil {
+			return nil, fmt.Errorf("file exporter endpoint error: %s", err.Error())
+		}
+		return stdouttrace.New(stdouttrace.WithWriter(f))
 	default:
 		return nil, fmt.Errorf("unknown exporter: %s", c.Batcher)
 	}

core/trace/agent_test.go

@@ -17,6 +17,7 @@ func TestStartAgent(t *testing.T) {
 		endpoint4 = "localhost:1236"
 		endpoint5 = "udp://localhost:6831"
 		endpoint6 = "localhost:1237"
+		endpoint7 = "/tmp/trace.log"
 	)
 	c1 := Config{
 		Name: "foo",
@@ -63,6 +64,11 @@ func TestStartAgent(t *testing.T) {
 		Endpoint: endpoint6,
 		Batcher:  kindJaeger,
 	}
+	c9 := Config{
+		Name:     "file",
+		Endpoint: endpoint7,
+		Batcher:  kindFile,
+	}
 
 	StartAgent(c1)
 	StartAgent(c1)
@@ -73,13 +79,14 @@ func TestStartAgent(t *testing.T) {
 	StartAgent(c6)
 	StartAgent(c7)
 	StartAgent(c8)
+	StartAgent(c9)
 	defer StopAgent()
 
 	lock.Lock()
 	defer lock.Unlock()
 
 	// because remotehost cannot be resolved
-	assert.Equal(t, 5, len(agents))
+	assert.Equal(t, 6, len(agents))
 	_, ok := agents[""]
 	assert.True(t, ok)
 	_, ok = agents[endpoint1]
@@ -90,4 +97,6 @@ func TestStartAgent(t *testing.T) {
 	assert.True(t, ok)
 	_, ok = agents[endpoint6]
 	assert.False(t, ok)
+	_, ok = agents[endpoint7]
+	assert.True(t, ok)
 }

core/trace/config.go

@@ -8,7 +8,7 @@ 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|otlpgrpc|otlphttp"`
+	Batcher  string  `json:",default=jaeger,options=jaeger|zipkin|otlpgrpc|otlphttp|file"`
 	// OtlpHeaders represents the headers for OTLP gRPC or HTTP transport.
 	// For example:
 	//  uptrace-dsn: 'http://project2_secret_token@localhost:14317/2'