Create resource.Default() with required attributes/default values (#1507

)

* Create resource.Default() with required attributes/default values

Add metric controller and tracer provider tests for resources

* Updated CHANGELOG

* PR comments

+ some small CHANGELOG PR addition, rewording
+ change default resource servicename to `unknown_service:go` (this
matches the Java codebase which uses `unknown_service:java`)

CHANGELOG.md

@@ -8,11 +8,15 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 ## [Unreleased]
 
+### Added
+
+- Added `resource.Default()` for use with meter and tracer providers. (#1507)
+
 ## [0.17.0] - 2020-02-12
 
 ### Changed
 
-- Rename project default branch from `master` to `main`.
+- Rename project default branch from `master` to `main`. (#1505)
 - Reverse order in which `Resource` attributes are merged, per change in spec. (#1501)
 - Add tooling to maintain "replace" directives in go.mod files automatically. (#1528)
 - Create new modules: otel/metric, otel/trace, otel/oteltest, otel/sdk/export/metric, otel/sdk/metric (#1528)

exporters/metric/prometheus/prometheus_test.go

@@ -117,6 +117,7 @@ func TestPrometheusStatefulness(t *testing.T) {
 	exporter, err := prometheus.NewExportPipeline(
 		prometheus.Config{},
 		controller.WithCollectPeriod(0),
+		controller.WithResource(resource.Empty()),
 	)
 	require.NoError(t, err)
 

sdk/metric/controller/basic/controller.go

@@ -26,6 +26,7 @@ import (
 	export "go.opentelemetry.io/otel/sdk/export/metric"
 	sdk "go.opentelemetry.io/otel/sdk/metric"
 	controllerTime "go.opentelemetry.io/otel/sdk/metric/controller/time"
+	"go.opentelemetry.io/otel/sdk/resource"
 )
 
 // DefaultPeriod is used for:
@@ -85,6 +86,9 @@ func New(checkpointer export.Checkpointer, opts ...Option) *Controller {
 	for _, opt := range opts {
 		opt.Apply(c)
 	}
+	if c.Resource == nil {
+		c.Resource = resource.Default()
+	}
 
 	impl := sdk.NewAccumulator(
 		checkpointer,

sdk/metric/controller/basic/controller_test.go

@@ -17,6 +17,7 @@ package basic_test
 import (
 	"context"
 	"errors"
+	"fmt"
 	"testing"
 	"time"
 
@@ -30,6 +31,7 @@ import (
 	"go.opentelemetry.io/otel/sdk/metric/controller/controllertest"
 	processor "go.opentelemetry.io/otel/sdk/metric/processor/basic"
 	"go.opentelemetry.io/otel/sdk/metric/processor/processortest"
+	"go.opentelemetry.io/otel/sdk/resource"
 )
 
 func getMap(t *testing.T, cont *controller.Controller) map[string]float64 {
@@ -55,13 +57,66 @@ func checkTestContext(t *testing.T, ctx context.Context) {
 	require.Equal(t, "B", ctx.Value(testContextKey("A")))
 }
 
+func TestControllerUsesResource(t *testing.T) {
+	cases := []struct {
+		name    string
+		options []controller.Option
+		wanted  string
+	}{
+		{
+			name:    "explicitly empty resource",
+			options: []controller.Option{controller.WithResource(resource.Empty())},
+			wanted:  ""},
+		{
+			name:    "uses default if no resource option",
+			options: nil,
+			wanted:  resource.Default().Encoded(label.DefaultEncoder())},
+		{
+			name:    "explicit resource",
+			options: []controller.Option{controller.WithResource(resource.NewWithAttributes(label.String("R", "S")))},
+			wanted:  "R=S"},
+		{
+			name: "last resource wins",
+			options: []controller.Option{
+				controller.WithResource(resource.Default()),
+				controller.WithResource(resource.NewWithAttributes(label.String("R", "S"))),
+			},
+			wanted: "R=S",
+		},
+	}
+	for _, c := range cases {
+		t.Run(fmt.Sprintf("case-%s", c.name), func(t *testing.T) {
+			cont := controller.New(
+				processor.New(
+					processortest.AggregatorSelector(),
+					export.CumulativeExportKindSelector(),
+				),
+				c.options...,
+			)
+			prov := cont.MeterProvider()
+
+			ctr := metric.Must(prov.Meter("named")).NewFloat64Counter("calls.sum")
+			ctr.Add(context.Background(), 1.)
+
+			// Collect once
+			require.NoError(t, cont.Collect(context.Background()))
+
+			expect := map[string]float64{
+				"calls.sum//" + c.wanted: 1.,
+			}
+			require.EqualValues(t, expect, getMap(t, cont))
+		})
+	}
+}
+
 func TestStartNoExporter(t *testing.T) {
 	cont := controller.New(
 		processor.New(
 			processortest.AggregatorSelector(),
 			export.CumulativeExportKindSelector(),
 		),
 		controller.WithCollectPeriod(time.Second),
+		controller.WithResource(resource.Empty()),
 	)
 	mock := controllertest.NewMockClock()
 	cont.SetClock(mock)
@@ -132,6 +187,7 @@ func TestObserverCanceled(t *testing.T) {
 		),
 		controller.WithCollectPeriod(0),
 		controller.WithCollectTimeout(time.Millisecond),
+		controller.WithResource(resource.Empty()),
 	)
 
 	prov := cont.MeterProvider()
@@ -163,6 +219,7 @@ func TestObserverContext(t *testing.T) {
 			export.CumulativeExportKindSelector(),
 		),
 		controller.WithCollectTimeout(0),
+		controller.WithResource(resource.Empty()),
 	)
 
 	prov := cont.MeterProvider()
@@ -228,6 +285,7 @@ func TestExportTimeout(t *testing.T) {
 		controller.WithCollectPeriod(time.Second),
 		controller.WithPushTimeout(time.Millisecond),
 		controller.WithPusher(exporter),
+		controller.WithResource(resource.Empty()),
 	)
 	mock := controllertest.NewMockClock()
 	cont.SetClock(mock)
@@ -283,6 +341,7 @@ func TestCollectAfterStopThenStartAgain(t *testing.T) {
 		),
 		controller.WithCollectPeriod(time.Second),
 		controller.WithPusher(exp),
+		controller.WithResource(resource.Empty()),
 	)
 	mock := controllertest.NewMockClock()
 	cont.SetClock(mock)

sdk/metric/controller/basic/pull_test.go

@@ -29,6 +29,7 @@ import (
 	"go.opentelemetry.io/otel/sdk/metric/controller/controllertest"
 	processor "go.opentelemetry.io/otel/sdk/metric/processor/basic"
 	"go.opentelemetry.io/otel/sdk/metric/processor/processortest"
+	"go.opentelemetry.io/otel/sdk/resource"
 )
 
 func TestPullNoCollect(t *testing.T) {
@@ -39,6 +40,7 @@ func TestPullNoCollect(t *testing.T) {
 			processor.WithMemory(true),
 		),
 		controller.WithCollectPeriod(0),
+		controller.WithResource(resource.Empty()),
 	)
 
 	ctx := context.Background()
@@ -74,6 +76,7 @@ func TestPullWithCollect(t *testing.T) {
 			processor.WithMemory(true),
 		),
 		controller.WithCollectPeriod(time.Second),
+		controller.WithResource(resource.Empty()),
 	)
 	mock := controllertest.NewMockClock()
 	puller.SetClock(mock)

sdk/resource/builtin.go

@@ -18,6 +18,7 @@ import (
 	"context"
 	"fmt"
 	"os"
+	"path/filepath"
 
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/label"
@@ -43,12 +44,15 @@ type (
 		K label.Key
 		F func() (string, error)
 	}
+
+	defaultServiceNameDetector struct{}
 )
 
 var (
 	_ Detector = TelemetrySDK{}
 	_ Detector = Host{}
 	_ Detector = stringDetector{}
+	_ Detector = defaultServiceNameDetector{}
 )
 
 // Detect returns a *Resource that describes the OpenTelemetry SDK used.
@@ -79,3 +83,17 @@ func (sd stringDetector) Detect(ctx context.Context) (*Resource, error) {
 	}
 	return NewWithAttributes(sd.K.String(value)), nil
 }
+
+// Detect implements Detector
+func (defaultServiceNameDetector) Detect(ctx context.Context) (*Resource, error) {
+	return StringDetector(
+		semconv.ServiceNameKey,
+		func() (string, error) {
+			executable, err := os.Executable()
+			if err != nil {
+				return "unknown_service:go", nil
+			}
+			return "unknown_service:" + filepath.Base(executable), nil
+		},
+	).Detect(ctx)
+}

sdk/resource/resource.go

@@ -15,6 +15,10 @@
 package resource // import "go.opentelemetry.io/otel/sdk/resource"
 
 import (
+	"context"
+
+	"go.opentelemetry.io/otel"
+
 	"go.opentelemetry.io/otel/label"
 )
 
@@ -29,7 +33,16 @@ type Resource struct {
 	labels label.Set
 }
 
-var emptyResource Resource
+var (
+	emptyResource Resource
+
+	defaultResource *Resource = func(r *Resource, err error) *Resource {
+		if err != nil {
+			otel.Handle(err)
+		}
+		return r
+	}(Detect(context.Background(), defaultServiceNameDetector{}, TelemetrySDK{}))
+)
 
 // NewWithAttributes creates a resource from a set of attributes.  If there are
 // duplicate keys present in the list of attributes, then the last
@@ -113,6 +126,12 @@ func Empty() *Resource {
 	return &emptyResource
 }
 
+// Default returns an instance of Resource with a default
+// "service.name" and OpenTelemetrySDK attributes
+func Default() *Resource {
+	return defaultResource
+}
+
 // Equivalent returns an object that can be compared for equality
 // between two resources.  This value is suitable for use as a key in
 // a map.

sdk/resource/resource_test.go

@@ -17,13 +17,16 @@ package resource_test
 import (
 	"encoding/json"
 	"fmt"
+	"strings"
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
 	"github.com/stretchr/testify/require"
 
+	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/label"
 	"go.opentelemetry.io/otel/sdk/resource"
+	"go.opentelemetry.io/otel/semconv"
 )
 
 var (
@@ -162,6 +165,21 @@ func TestMerge(t *testing.T) {
 	}
 }
 
+func TestDefault(t *testing.T) {
+	res := resource.Default()
+	require.False(t, res.Equal(resource.Empty()))
+	require.True(t, res.LabelSet().HasValue(semconv.ServiceNameKey))
+
+	serviceName, _ := res.LabelSet().Value(semconv.ServiceNameKey)
+	require.True(t, strings.HasPrefix(serviceName.AsString(), "unknown_service:"))
+	require.Greaterf(t, len(serviceName.AsString()), len("unknown_service:"),
+		"default service.name should include executable name")
+
+	require.Contains(t, res.Attributes(), semconv.TelemetrySDKLanguageGo)
+	require.Contains(t, res.Attributes(), semconv.TelemetrySDKVersionKey.String(otel.Version()))
+	require.Contains(t, res.Attributes(), semconv.TelemetrySDKNameKey.String("opentelemetry"))
+}
+
 func TestString(t *testing.T) {
 	for _, test := range []struct {
 		kvs  []label.KeyValue

sdk/trace/provider.go

@@ -179,8 +179,9 @@ func (p *TracerProvider) ApplyConfig(cfg Config) {
 	if cfg.MaxLinksPerSpan > 0 {
 		c.MaxLinksPerSpan = cfg.MaxLinksPerSpan
 	}
-	if cfg.Resource != nil {
-		c.Resource = cfg.Resource
+	c.Resource = cfg.Resource
+	if c.Resource == nil {
+		c.Resource = resource.Default()
 	}
 	p.config.Store(&c)
 }