Add stdout trace exporter (#153)

* Add stdout trace exporter (#134)

* Update go.mod and go.sum

* Do not use assert in tests

Author: Steven Karis

example/README.md

@@ -28,32 +28,20 @@ Example uses
 GO111MODULE="" go get -d go.opentelemetry.io
 ```
 
-#### 2 Start All-in-one Jaeger
-
-```
-docker run -d --name jaeger \
-  -p 16686:16686 \
-  -p 14268:14268 \
-  jaegertracing/all-in-one:1.8
-```
-
-#### 3 Start Server
+#### 2 Start Server
 ```
 cd $GOPATH/src/go.opentelemetry.io/example/http/
 go run ./server/server.go
 ``` 
 
-#### 4 Start Client
+#### 3 Start Client
 ```
 cd $GOPATH/src/go.opentelemetry.io/example/http/
 go run ./client/client.go
 ``` 
 
-#### 5 Check traces on Jaeger UI
-
-Visit http://localhost:16686 with a web browser
-Click on 'Find' to see traces.
+#### 4 Check traces in stdout
 
-[Sample Snapshot](http/images/JaegarTraceExample.png)
+The spans should be visible in stdout in the order that they were exported.
 
 

example/http/client/client.go

@@ -28,7 +28,7 @@ import (
 	"go.opentelemetry.io/api/key"
 	"go.opentelemetry.io/api/tag"
 	"go.opentelemetry.io/api/trace"
-	"go.opentelemetry.io/exporter/trace/jaeger"
+	"go.opentelemetry.io/exporter/trace/stdout"
 	"go.opentelemetry.io/plugin/httptrace"
 	sdktrace "go.opentelemetry.io/sdk/trace"
 )
@@ -37,14 +37,9 @@ func initTracer() {
 	// Register SDK as trace provider.
 	sdktrace.Register()
 
-	// Create Jaeger exporter to be able to retrieve
+	// Create stdout exporter to be able to retrieve
 	// the collected spans.
-	exporter, err := jaeger.NewExporter(jaeger.Options{
-		CollectorEndpoint: "http://localhost:14268/api/traces",
-		Process: jaeger.Process{
-			ServiceName: "trace-demo",
-		},
-	})
+	exporter, err := stdout.NewExporter(stdout.Options{PrettyPrint: true})
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -94,5 +89,5 @@ func main() {
 	fmt.Printf("Response Received: %s\n\n\n", body)
 	fmt.Printf("Waiting for few seconds to export spans ...\n\n")
 	time.Sleep(10 * time.Second)
-	fmt.Printf("Check traces on http://localhost:16686\n")
+	fmt.Printf("Inspect traces on stdout")
 }

example/http/go.sum

@@ -84,6 +84,7 @@ github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
 github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/logrusorgru/aurora v0.0.0-20181002194514-a7b3b318ed4e/go.mod h1:7rIyQOR62GCctdiQpZ/zOJlFyk6y+94wXzv6RNZgaR4=
+github.com/magiconair/properties v1.7.6 h1:U+1DqNen04MdEPgFiIwdOUiqZ8qPa37xgogX/sd3+54=
 github.com/magiconair/properties v1.7.6/go.mod h1:PppfXfuXeibc/6YijjN8zIbojt8czPbwD3XqdrwzmxQ=
 github.com/mattn/go-colorable v0.0.9/go.mod h1:9vuHe8Xs5qXnSaW/c/ABM9alt+Vo+STaOChaDxuIBZU=
 github.com/mattn/go-isatty v0.0.3/go.mod h1:M+lRXTBqGeGNdLjl/ufCoiOlB5xdOkqRJdNxMWT7Zi4=

example/http/server/server.go

@@ -21,7 +21,7 @@ import (
 
 	"go.opentelemetry.io/api/tag"
 	"go.opentelemetry.io/api/trace"
-	"go.opentelemetry.io/exporter/trace/jaeger"
+	"go.opentelemetry.io/exporter/trace/stdout"
 	"go.opentelemetry.io/plugin/httptrace"
 	sdktrace "go.opentelemetry.io/sdk/trace"
 )
@@ -31,12 +31,7 @@ func initTracer() {
 
 	// Create Jaeger exporter to be able to retrieve
 	// the collected spans.
-	exporter, err := jaeger.NewExporter(jaeger.Options{
-		CollectorEndpoint: "http://localhost:14268/api/traces",
-		Process: jaeger.Process{
-			ServiceName: "trace-demo",
-		},
-	})
+	exporter, err := stdout.NewExporter(stdout.Options{PrettyPrint: true})
 	if err != nil {
 		log.Fatal(err)
 	}

exporter/trace/stdout/doc.go

@@ -0,0 +1,16 @@
+// Copyright 2019, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package stdout contains an OpenTelemetry tracing exporter for writing to stdout.
+package stdout // import "go.opentelemetry.io/exporter/trace/stdout"

exporter/trace/stdout/stdout.go

@@ -0,0 +1,61 @@
+// Copyright 2019, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package stdout
+
+import (
+	"encoding/json"
+	"io"
+	"os"
+
+	"go.opentelemetry.io/sdk/trace"
+)
+
+// Options are the options to be used when initializing a stdout exporter.
+type Options struct {
+	// PrettyPrint will pretty the json representation of the span,
+	// making it print "pretty". Default is false.
+	PrettyPrint bool
+}
+
+// Exporter is an implementation of trace.Exporter that writes spans to stdout.
+type Exporter struct {
+	pretty       bool
+	outputWriter io.Writer
+}
+
+func NewExporter(o Options) (*Exporter, error) {
+	return &Exporter{
+		pretty:       o.PrettyPrint,
+		outputWriter: os.Stdout,
+	}, nil
+}
+
+// ExportSpan writes a SpanData in json format to stdout.
+func (e *Exporter) ExportSpan(data *trace.SpanData) {
+	var jsonSpan []byte
+	var err error
+	if e.pretty {
+		jsonSpan, err = json.MarshalIndent(data, "", "\t")
+	} else {
+		jsonSpan, err = json.Marshal(data)
+	}
+	if err != nil {
+		// ignore writer failures for now
+		_, _ = e.outputWriter.Write([]byte("Error converting spanData to json: " + err.Error()))
+		return
+	}
+	// ignore writer failures for now
+	_, _ = e.outputWriter.Write(append(jsonSpan, byte('\n')))
+}

exporter/trace/stdout/stdout_test.go

@@ -0,0 +1,101 @@
+// Copyright 2019, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package stdout
+
+import (
+	"bytes"
+	"encoding/json"
+	"testing"
+	"time"
+
+	"google.golang.org/grpc/codes"
+
+	"go.opentelemetry.io/api/core"
+	"go.opentelemetry.io/sdk/trace"
+)
+
+func TestExporter_ExportSpan(t *testing.T) {
+	exporter, err := NewExporter(Options{})
+	if err != nil {
+		t.Errorf("Error constructing stdout exporter %s", err)
+	}
+
+	// override output writer for testing
+	var b bytes.Buffer
+	exporter.outputWriter = &b
+
+	// setup test span
+	now := time.Now()
+	traceID := core.TraceID{High: 0x0102030405060708, Low: 0x090a0b0c0d0e0f10}
+	spanID := uint64(0x0102030405060708)
+	keyValue := "value"
+	doubleValue := float64(123.456)
+
+	testSpan := &trace.SpanData{
+		SpanContext: core.SpanContext{
+			TraceID: traceID,
+			SpanID:  spanID,
+		},
+		Name:      "/foo",
+		StartTime: now,
+		EndTime:   now,
+		Attributes: []core.KeyValue{
+			{
+				Key:   core.Key{Name: "key"},
+				Value: core.Value{Type: core.STRING, String: keyValue},
+			},
+			{
+				Key:   core.Key{Name: "double"},
+				Value: core.Value{Type: core.FLOAT64, Float64: doubleValue},
+			},
+		},
+		Status: codes.Unknown,
+	}
+	exporter.ExportSpan(testSpan)
+
+	expectedSerializedNow, _ := json.Marshal(now)
+
+	got := b.String()
+	expectedOutput := `{"SpanContext":{` +
+		`"TraceID":{"High":72623859790382856,"Low":651345242494996240},` +
+		`"SpanID":72623859790382856,"TraceFlags":0},` +
+		`"ParentSpanID":0,` +
+		`"SpanKind":0,` +
+		`"Name":"/foo",` +
+		`"StartTime":` + string(expectedSerializedNow) + "," +
+		`"EndTime":` + string(expectedSerializedNow) + "," +
+		`"Attributes":[` +
+		`{` +
+		`"Key":{"Name":"key"},` +
+		`"Value":{"Type":8,"Bool":false,"Int64":0,"Uint64":0,"Float64":0,"String":"value","Bytes":null}` +
+		`},` +
+		`{` +
+		`"Key":{"Name":"double"},` +
+		`"Value":{"Type":7,"Bool":false,"Int64":0,"Uint64":0,"Float64":123.456,"String":"","Bytes":null}` +
+		`}` +
+		`],` +
+		`"MessageEvents":null,` +
+		`"Links":null,` +
+		`"Status":2,` +
+		`"HasRemoteParent":false,` +
+		`"DroppedAttributeCount":0,` +
+		`"DroppedMessageEventCount":0,` +
+		`"DroppedLinkCount":0,` +
+		`"ChildSpanCount":0}` + "\n"
+
+	if got != expectedOutput {
+		t.Errorf("Want: %v but got: %v", expectedOutput, got)
+	}
+}