GCE Resource Detector (#132)

Implements detection of GCP resource tags.

.github/dependabot.yml

@@ -9,6 +9,10 @@ updates:
     directory: "/" # Location of package manifests
     schedule:
       interval: "daily"
+  - package-ecosystem: "gomod" # See documentation for possible values
+    directory: "/detectors/gcp" # Location of package manifests
+    schedule:
+      interval: "daily"
   - package-ecosystem: "gomod" # See documentation for possible values
     directory: "/tools" # Location of package manifests
     schedule:

CHANGELOG.md

@@ -10,9 +10,11 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 
 ### Added
 
+- Create a detector that collects resources from GCE machines. (#132)
 - Add instrumentation for Kafka (github.com/Shopify/sarama). (#134)
 - Add links and status message for mock span. (#134)
 
+
 ## [0.9.0] - 2020-07-20
 
 This release upgrades its [go.opentelemetry.io/otel](https://github.com/open-telemetry/opentelemetry-go/releases/tag/v0.9.0) dependency to v0.9.0.
@@ -23,6 +25,7 @@ This release upgrades its [go.opentelemetry.io/otel](https://github.com/open-tel
 - Update dependabot configuration to correctly check all included packages. (#131)
 - Update `RELEASING.md` with correct `tag.sh` command. (#130)
 
+
 ## [0.8.0] - 2020-07-10
 
 This release upgrades its [go.opentelemetry.io/otel](https://github.com/open-telemetry/opentelemetry-go/releases/tag/v0.8.0) dependency to v0.8.0, includes minor fixes, and new instrumentation.

detectors/gcp/gce.go

@@ -0,0 +1,106 @@
+// Copyright The 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 gcp
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"strings"
+
+	"cloud.google.com/go/compute/metadata"
+
+	"go.opentelemetry.io/otel/api/kv"
+	"go.opentelemetry.io/otel/api/standard"
+	"go.opentelemetry.io/otel/sdk/resource"
+)
+
+// GCE collects resource information of GCE computing instances
+type GCE struct{}
+
+// compile time assertion that GCE implements the resource.Detector interface.
+var _ resource.Detector = (*GCE)(nil)
+
+// Detect detects associated resources when running on GCE hosts.
+func (gce *GCE) Detect(ctx context.Context) (*resource.Resource, error) {
+	if !metadata.OnGCE() {
+		return nil, nil
+	}
+
+	labels := []kv.KeyValue{
+		standard.CloudProviderGCP,
+	}
+
+	var errInfo []string
+
+	if projectID, err := metadata.ProjectID(); hasProblem(err) {
+		errInfo = append(errInfo, err.Error())
+	} else if projectID != "" {
+		labels = append(labels, standard.CloudAccountIDKey.String(projectID))
+	}
+
+	if zone, err := metadata.Zone(); hasProblem(err) {
+		errInfo = append(errInfo, err.Error())
+	} else if zone != "" {
+		labels = append(labels, standard.CloudZoneKey.String(zone))
+
+		splitArr := strings.SplitN(zone, "-", 3)
+		if len(splitArr) == 3 {
+			standard.CloudRegionKey.String(strings.Join(splitArr[0:2], "-"))
+		}
+	}
+
+	if instanceID, err := metadata.InstanceID(); hasProblem(err) {
+		errInfo = append(errInfo, err.Error())
+	} else if instanceID != "" {
+		labels = append(labels, standard.HostIDKey.String(instanceID))
+	}
+
+	if name, err := metadata.InstanceName(); hasProblem(err) {
+		errInfo = append(errInfo, err.Error())
+	} else if name != "" {
+		labels = append(labels, standard.HostNameKey.String(name))
+	}
+
+	if hostname, err := os.Hostname(); hasProblem(err) {
+		errInfo = append(errInfo, err.Error())
+	} else if hostname != "" {
+		labels = append(labels, standard.HostHostNameKey.String(hostname))
+	}
+
+	if hostType, err := metadata.Get("instance/machine-type"); hasProblem(err) {
+		errInfo = append(errInfo, err.Error())
+	} else if hostType != "" {
+		labels = append(labels, standard.HostTypeKey.String(hostType))
+	}
+
+	var aggregatedErr error
+	if len(errInfo) > 0 {
+		aggregatedErr = fmt.Errorf("detecting GCE resources: %s", errInfo)
+	}
+
+	return resource.New(labels...), aggregatedErr
+}
+
+// hasProblem checks if the err is not nil or for missing resources
+func hasProblem(err error) bool {
+	if err == nil {
+		return false
+	}
+	if _, undefined := err.(metadata.NotDefinedError); undefined {
+		return false
+	}
+	return true
+}

detectors/gcp/go.mod

@@ -0,0 +1,8 @@
+module go.opentelemetry.io/contrib/detectors/gcp
+
+go 1.14
+
+require (
+	cloud.google.com/go v0.61.0
+	go.opentelemetry.io/otel v0.9.0
+)