Add Stackdriver Exporter and configs.

Fixes open-telemetry#6.

exporter/stackdriverexporter/config.go

@@ -0,0 +1,26 @@
+// 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 stackdriverexporter
+
+import "github.com/open-telemetry/opentelemetry-service/config/configmodels"
+
+// Config defines configuration for Stackdriver exporter.
+type Config struct {
+	configmodels.ExporterSettings `mapstructure:",squash"` // squash ensures fields are correctly decoded in embedded struct.
+	ProjectID                     string                   `mapstructure:"project"`
+	EnableTracing                 bool                     `mapstructure:"enable_tracing"`
+	EnableMetrics                 bool                     `mapstructure:"enable_metrics"`
+	Prefix                        string                   `mapstructure:"metric_prefix"`
+}

exporter/stackdriverexporter/config_test.go

@@ -0,0 +1,52 @@
+// 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 stackdriverexporter
+
+import (
+	"path"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/open-telemetry/opentelemetry-service/config"
+	"github.com/open-telemetry/opentelemetry-service/config/configmodels"
+	"github.com/open-telemetry/opentelemetry-service/exporter"
+)
+
+var _ = config.RegisterTestFactories()
+
+func TestLoadConfig(t *testing.T) {
+
+	factory := exporter.GetFactory(typeStr)
+
+	cfg, err := config.LoadConfigFile(t, path.Join(".", "testdata", "config.yaml"))
+
+	require.NoError(t, err)
+	require.NotNil(t, cfg)
+
+	assert.Equal(t, len(cfg.Exporters), 2)
+
+	r0 := cfg.Exporters["stackdriver"]
+	assert.Equal(t, r0, factory.CreateDefaultConfig())
+
+	r1 := cfg.Exporters["stackdriver/customname"].(*Config)
+	assert.Equal(t, r1.ExporterSettings,
+		configmodels.ExporterSettings{
+			TypeVal: typeStr,
+			NameVal: "stackdriver/customname",
+			Enabled: true,
+		})
+}

exporter/stackdriverexporter/factory.go

@@ -0,0 +1,66 @@
+// 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 stackdriverexporter
+
+import (
+	"github.com/open-telemetry/opentelemetry-service/config/configmodels"
+	"github.com/open-telemetry/opentelemetry-service/consumer"
+	"github.com/open-telemetry/opentelemetry-service/exporter"
+	"go.uber.org/zap"
+)
+
+var _ = exporter.RegisterFactory(&exporterFactory{})
+
+const (
+	// The value of "type" key in configuration.
+	typeStr = "stackdriver"
+)
+
+// exporterFactory is the factory for OpenCensus exporter.
+type exporterFactory struct {
+}
+
+// Type gets the type of the Exporter config created by this factory.
+func (f *exporterFactory) Type() string {
+	return typeStr
+}
+
+// CreateDefaultConfig creates the default configuration for exporter.
+func (f *exporterFactory) CreateDefaultConfig() configmodels.Exporter {
+	return &Config{
+		ExporterSettings: configmodels.ExporterSettings{
+			TypeVal: typeStr,
+			NameVal: typeStr,
+		},
+	}
+}
+
+// CreateTraceExporter creates a trace exporter based on this config.
+func (f *exporterFactory) CreateTraceExporter(logger *zap.Logger, cfg configmodels.Exporter) (consumer.TraceConsumer, exporter.StopFunc, error) {
+	eCfg := cfg.(*Config)
+	if !eCfg.EnableTracing {
+		return nil, nil, nil
+	}
+	return newStackdriverTraceExporter(eCfg.ProjectID, eCfg.Prefix)
+}
+
+// CreateMetricsExporter creates a metrics exporter based on this config.
+func (f *exporterFactory) CreateMetricsExporter(logger *zap.Logger, cfg configmodels.Exporter) (consumer.MetricsConsumer, exporter.StopFunc, error) {
+	eCfg := cfg.(*Config)
+	if !eCfg.EnableMetrics {
+		return nil, nil, nil
+	}
+	return newStackdriverMetricsExporter(eCfg.ProjectID, eCfg.Prefix)
+}

exporter/stackdriverexporter/factory_test.go

@@ -0,0 +1,42 @@
+// 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 stackdriverexporter
+
+import (
+	"testing"
+
+	"go.uber.org/zap"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/open-telemetry/opentelemetry-service/exporter"
+)
+
+func TestCreateDefaultConfig(t *testing.T) {
+	factory := exporter.GetFactory(typeStr)
+	cfg := factory.CreateDefaultConfig()
+	assert.NotNil(t, cfg, "failed to create default config")
+}
+
+func TestCreateExporter(t *testing.T) {
+	factory := exporter.GetFactory(typeStr)
+	cfg := factory.CreateDefaultConfig()
+
+	_, _, err := factory.CreateTraceExporter(zap.NewNop(), cfg)
+	assert.Nil(t, err)
+
+	_, _, err = factory.CreateMetricsExporter(zap.NewNop(), cfg)
+	assert.Nil(t, err)
+}

exporter/stackdriverexporter/stackdriver.go

@@ -0,0 +1,181 @@
+// 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 stackdriverexporter contains the wrapper for OpenTelemetry-Stackdriver
+// exporter to be used in OpenTelemetry-Service.
+package stackdriverexporter
+
+import (
+	"context"
+	"fmt"
+	"sync"
+	"time"
+
+	"contrib.go.opencensus.io/exporter/stackdriver"
+	"github.com/spf13/viper"
+	"go.opencensus.io/trace"
+
+	"github.com/open-telemetry/opentelemetry-service/consumer"
+	"github.com/open-telemetry/opentelemetry-service/consumer/consumerdata"
+	"github.com/open-telemetry/opentelemetry-service/exporter/exporterwrapper"
+)
+
+type stackdriverConfig struct {
+	ProjectID     string `mapstructure:"project,omitempty"`
+	EnableTracing bool   `mapstructure:"enable_tracing,omitempty"`
+	EnableMetrics bool   `mapstructure:"enable_metrics,omitempty"`
+	MetricPrefix  string `mapstructure:"metric_prefix,omitempty"`
+}
+
+// TODO: Add metrics support to the exporterwrapper.
+type stackdriverExporter struct {
+	exporter *stackdriver.Exporter
+}
+
+var _ consumer.MetricsConsumer = (*stackdriverExporter)(nil)
+
+// StackdriverTraceExportersFromViper unmarshals the viper and returns an consumer.TraceConsumer targeting
+// Stackdriver according to the configuration settings.
+func StackdriverTraceExportersFromViper(v *viper.Viper) (tps []consumer.TraceConsumer, mps []consumer.MetricsConsumer, doneFns []func() error, err error) {
+	var cfg struct {
+		Stackdriver *stackdriverConfig `mapstructure:"stackdriver"`
+	}
+	if err := v.Unmarshal(&cfg); err != nil {
+		return nil, nil, nil, err
+	}
+	sc := cfg.Stackdriver
+	if sc == nil {
+		return nil, nil, nil, nil
+	}
+	if !sc.EnableTracing && !sc.EnableMetrics {
+		return nil, nil, nil, nil
+	}
+
+	sde, serr := newStackdriverExporter(sc.ProjectID, sc.MetricPrefix)
+
+	if serr != nil {
+		return nil, nil, nil, fmt.Errorf("Cannot configure Stackdriver exporter: %v", serr)
+	}
+
+	exp := &stackdriverExporter{
+		exporter: sde,
+	}
+
+	sdte, err := exporterwrapper.NewExporterWrapper("stackdriver_trace", "ocservice.exporter.Stackdriver.ConsumeTraceData", sde)
+	if err != nil {
+		return nil, nil, nil, err
+	}
+
+	// TODO: Examine "contrib.go.opencensus.io/exporter/stackdriver" to see
+	// if trace.ExportSpan was constraining and if perhaps the Stackdriver
+	// upload can use the context and information from the Node.
+	if sc.EnableTracing {
+		tps = append(tps, sdte)
+	}
+
+	if sc.EnableMetrics {
+		mps = append(mps, exp)
+	}
+
+	doneFns = append(doneFns, func() error {
+		sde.Flush()
+		return nil
+	})
+	return
+}
+
+func newStackdriverTraceExporter(ProjectID, MetricPrefix string) (consumer.TraceConsumer, func() error, error) {
+	sde, serr := newStackdriverExporter(ProjectID, MetricPrefix)
+	if serr != nil {
+		return nil, nil, fmt.Errorf("Cannot configure Stackdriver Trace exporter: %v", serr)
+	}
+
+	tExp, err := exporterwrapper.NewExporterWrapper("stackdriver_trace", "ocservice.exporter.Stackdriver.ConsumeTraceData", sde)
+	if err != nil {
+		return nil, nil, err
+	}
+	// TODO: Examine "contrib.go.opencensus.io/exporter/stackdriver" to see
+	// if trace.ExportSpan was constraining and if perhaps the Stackdriver
+	// upload can use the context and information from the Node.
+
+	doneFn := func() error {
+		sde.Flush()
+		return nil
+	}
+
+	return tExp, doneFn, nil
+}
+
+func newStackdriverMetricsExporter(ProjectID, MetricPrefix string) (consumer.MetricsConsumer, func() error, error) {
+	sde, serr := newStackdriverExporter(ProjectID, MetricPrefix)
+	if serr != nil {
+		return nil, nil, fmt.Errorf("Cannot configure Stackdriver metric exporter: %v", serr)
+	}
+
+	mExp := &stackdriverExporter{
+		exporter: sde,
+	}
+
+	doneFn := func() error {
+		sde.Flush()
+		return nil
+	}
+
+	return mExp, doneFn, nil
+}
+
+func newStackdriverExporter(ProjectID, MetricPrefix string) (*stackdriver.Exporter, error) {
+	// TODO:  For each ProjectID, create a different exporter
+	// or at least a unique Stackdriver client per ProjectID.
+
+	return stackdriver.NewExporter(stackdriver.Options{
+		// If the project ID is an empty string, it will be set by default based on
+		// the project this is running on in GCP.
+		ProjectID: ProjectID,
+
+		MetricPrefix: MetricPrefix,
+
+		// Stackdriver Metrics mandates a minimum of 60 seconds for
+		// reporting metrics. We have to enforce this as per the advisory
+		// at https://cloud.google.com/monitoring/custom-metrics/creating-metrics#writing-ts
+		// which says:
+		//
+		// "If you want to write more than one point to the same time series, then use a separate call
+		//  to the timeSeries.create method for each point. Don't make the calls faster than one time per
+		//  minute. If you are adding data points to different time series, then there is no rate limitation."
+		BundleDelayThreshold: 61 * time.Second,
+	})
+}
+
+func (sde *stackdriverExporter) ConsumeMetricsData(ctx context.Context, md consumerdata.MetricsData) error {
+	ctx, span := trace.StartSpan(ctx,
+		"opencensus.service.exporter.stackdriver.ExportMetricsData",
+		trace.WithSampler(trace.NeverSample()))
+	defer span.End()
+
+	var setErrorOnce sync.Once
+
+	err := sde.exporter.ExportMetricsProto(ctx, md.Node, md.Resource, md.Metrics)
+	if err != nil {
+		setErrorOnce.Do(func() {
+			span.SetStatus(trace.Status{Code: trace.StatusCodeInternal, Message: err.Error()})
+		})
+
+		span.Annotate([]trace.Attribute{
+			trace.StringAttribute("error", err.Error()),
+		}, "Error encountered")
+	}
+
+	return nil
+}

exporter/stackdriverexporter/testdata/config.yaml

@@ -0,0 +1,21 @@
+receivers:
+  examplereceiver:
+
+processors:
+  exampleprocessor:
+
+exporters:
+  stackdriver:
+  stackdriver/customname:
+    enabled: true
+    project: my-project
+    enable_tracing: true
+    enable_metrics: true
+    metric_prefix: prefix
+
+pipelines:
+  traces:
+      receivers: [examplereceiver]
+      processors: [exampleprocessor]
+      exporters: [stackdriver]
+