Initialize opencensus for GKE (#176)

* Initialize opencensus for GKE

* update readme

* Generalize initialization of sd exporter

* fix sdExporterOptions

* do not initilize SD exporters and error reporting unless we are in the cloud or set proper environment variables

* Update doc

* address comments

* remove redundant if

README.md

@@ -31,11 +31,13 @@ The `server/kit` package embodies Gizmo's goals to combine with go-kit.
 * In this package you'll find:
     * A more opinionated server with fewer choices.
     * go-kit used for serving HTTP/JSON & gRPC used for serving HTTP2/RPC
-    * Monitoring and metrics are automatically registered if running within App Engine.
+    * Monitoring, traces and metrics are automatically registered if running within App Engine, Kubernetes Engine, Compute Engine or AWS EC2 Instances.
+        * to change the name and version for Error reporting and Traces use `SERVICE_NAME` and `SERVICE_VERSION` environment variables.
     * Logs go to stdout locally or directly to Stackdriver when in GCP.
     * Using Go's 1.8 graceful HTTP shutdown.
     * Services using this package are expected to deploy to GCP.
 
+
 #### [`auth`](https://godoc.org/github.com/NYTimes/gizmo/auth)
 
 The `auth` package provides primitives for verifying inbound authentication tokens:

server/kit/gae_log.go

@@ -18,7 +18,7 @@ import (
 
 // project, service, version
 func getGAEInfo() (string, string, string) {
-	return os.Getenv("GOOGLE_CLOUD_PROJECT"),
+	return googleProjectID(),
 		os.Getenv("GAE_SERVICE"),
 		os.Getenv("GAE_VERSION")
 }

server/kit/kitserver.go

@@ -8,6 +8,7 @@ import (
 	"net"
 	"net/http"
 	"net/http/pprof"
+	"os"
 	"strings"
 
 	"cloud.google.com/go/errorreporting"
@@ -87,12 +88,28 @@ func NewServer(svc Service) *Server {
 		errs  *errorreporting.Client
 		propr propagation.HTTPFormat
 	)
-	// if in App Engine, initiate an error reporter and the stackdriver exporters
+
+	projectID := googleProjectID()
+	var svcName, svcVersion string
 	if isGAE() {
-		projectID, serviceID, svcVersion := getGAEInfo()
+		_, svcName, svcVersion = getGAEInfo()
+	} else if n, v := os.Getenv("SERVICE_NAME"), os.Getenv("SERVICE_VERSION"); n != "" {
+		svcName, svcVersion = n, v
+	}
+
+	if opt := sdExporterOptions(projectID, svcName, svcVersion, lg); opt != nil {
+		err = initSDExporter(*opt)
+		if err != nil {
+			lg.Log("error", err,
+				"message", "unable to initiate error tracing exporter")
+		}
+
+		propr = &sdpropagation.HTTPFormat{}
+
 		errs, err = errorreporting.NewClient(ctx, projectID, errorreporting.Config{
-			ServiceName:    serviceID,
+			ServiceName:    svcName,
 			ServiceVersion: svcVersion,
+
 			OnError: func(err error) {
 				lg.Log("error", err,
 					"message", "error reporting client encountered an error")
@@ -102,14 +119,6 @@ func NewServer(svc Service) *Server {
 			lg.Log("error", err,
 				"message", "unable to initiate error reporting client")
 		}
-
-		err = initSDExporter(projectID, serviceID, svcVersion, lg)
-		if err != nil {
-			lg.Log("error", err,
-				"message", "unable to initiate error tracing exporter")
-		}
-
-		propr = &sdpropagation.HTTPFormat{}
 	}
 
 	s := &Server{

server/kit/stackdriver.go

@@ -1,20 +1,34 @@
 package kit
 
 import (
+	"os"
+
 	"contrib.go.opencensus.io/exporter/stackdriver"
+	"contrib.go.opencensus.io/exporter/stackdriver/monitoredresource"
 	"github.com/go-kit/kit/log"
 	"go.opencensus.io/stats/view"
 	"go.opencensus.io/trace"
 )
 
-func initSDExporter(projectID, service, version string, lg log.Logger) error {
-	exporter, err := stackdriver.NewExporter(stackdriver.Options{
-		ProjectID: projectID,
-		MonitoredResource: gaeInterface{
+func sdExporterOptions(projectID, service, version string, lg log.Logger) *stackdriver.Options {
+	var mr monitoredresource.Interface
+	if m := monitoredresource.Autodetect(); m != nil {
+		mr = m
+	} else if isGAE() {
+		mr = gaeInterface{
+			typ: "gae_app",
 			labels: map[string]string{
 				"project_id": projectID,
 			},
-		},
+		}
+	}
+	if mr == nil {
+		return nil
+	}
+
+	return &stackdriver.Options{
+		ProjectID:         projectID,
+		MonitoredResource: mr,
 		OnError: func(err error) {
 			lg.Log("error", err,
 				"message", "tracing client encountered an error")
@@ -24,7 +38,15 @@ func initSDExporter(projectID, service, version string, lg log.Logger) error {
 			"service": service,
 			"version": version,
 		},
-	})
+	}
+}
+
+func googleProjectID() string {
+	return os.Getenv("GOOGLE_CLOUD_PROJECT")
+}
+
+func initSDExporter(opt stackdriver.Options) error {
+	exporter, err := stackdriver.NewExporter(opt)
 	if err != nil {
 		return err
 	}
@@ -35,9 +57,10 @@ func initSDExporter(projectID, service, version string, lg log.Logger) error {
 
 // implements contrib.go.opencensus.io/exporter/stackdriver/monitoredresource.Interface
 type gaeInterface struct {
+	typ    string
 	labels map[string]string
 }
 
 func (g gaeInterface) MonitoredResource() (string, map[string]string) {
-	return "gae_app", g.labels
+	return g.typ, g.labels
 }