Add Jaeger support for Adservice. (#111)

This is the first service that exports to jaeger. Others to follow.
Requires jaeger to be instantiated using 

- helm install --name jaeger stable/jaeger-operator
- kubectl apply -f jaeger.yaml

=== jaeger.yaml Content ===
apiVersion: io.jaegertracing/v1alpha1
kind: Jaeger
metadata:
  name: jaeger

Above steps will be added to README in subsequent PR.

kubernetes-manifests/adservice.yaml

@@ -31,6 +31,8 @@ spec:
         env:
         - name: PORT
           value: "9555"
+        - name: JAEGER_ENABLED
+          value: "false"
         resources:
           requests:
             cpu: 200m

src/adservice/build.gradle

@@ -28,7 +28,6 @@ version = "0.1.0-SNAPSHOT" // CURRENT_OPENCENSUS_VERSION
 def opencensusVersion = "0.17.0" // LATEST_OPENCENSUS_RELEASE_VERSION
 def grpcVersion = "1.15.0" // CURRENT_GRPC_VERSION
 def jacksonVersion = "2.9.6"
-def prometheusVersion = "0.3.0"
 
 tasks.withType(JavaCompile) {
     sourceCompatibility = '1.8'
@@ -45,7 +44,7 @@ dependencies {
         compile fileTree(dir: offlineCompile, include: '*.jar')
     } else {
         compile "com.google.api.grpc:proto-google-common-protos:1.11.0",
-                "io.opencensus:opencensus-exporter-stats-prometheus:${opencensusVersion}",
+                "io.opencensus:opencensus-exporter-trace-jaeger:${opencensusVersion}",
                 "io.opencensus:opencensus-exporter-stats-stackdriver:${opencensusVersion}",
                 "io.opencensus:opencensus-exporter-trace-stackdriver:${opencensusVersion}",
                 "io.opencensus:opencensus-exporter-trace-logging:${opencensusVersion}",
@@ -53,7 +52,6 @@ dependencies {
                 "io.grpc:grpc-stub:${grpcVersion}",
                 "io.grpc:grpc-netty:${grpcVersion}",
                 "io.grpc:grpc-services:${grpcVersion}",
-                "io.prometheus:simpleclient_httpserver:${prometheusVersion}",
                 "org.apache.logging.log4j:log4j-core:2.11.1"
 
         runtime "com.fasterxml.jackson.core:jackson-core:${jacksonVersion}",

src/adservice/src/main/java/hipstershop/AdService.java

@@ -31,7 +31,7 @@ import io.grpc.services.*;
 import io.opencensus.common.Duration;
 import io.opencensus.common.Scope;
 import io.opencensus.contrib.grpc.metrics.RpcViews;
-import io.opencensus.exporter.stats.prometheus.PrometheusStatsCollector;
+import io.opencensus.exporter.trace.jaeger.JaegerTraceExporter;
 import io.opencensus.exporter.trace.logging.LoggingTraceExporter;
 import io.opencensus.exporter.stats.stackdriver.StackdriverStatsConfiguration;
 import io.opencensus.exporter.stats.stackdriver.StackdriverStatsExporter;
@@ -46,7 +46,6 @@ import io.opencensus.trace.samplers.Samplers;
 import java.io.IOException;
 import java.util.Collection;
 import java.util.ArrayList;
-import java.util.HashMap;
 import java.util.List;
 import java.util.Random;
 import java.util.concurrent.TimeUnit;
@@ -201,11 +200,6 @@ public class AdService {
   public static void initStackdriver() {
     logger.info("Initialize StackDriver");
 
-    // Registers all RPC views.
-    RpcViews.registerAllViews();
-
-    // Registers logging trace exporter.
-    LoggingTraceExporter.register();
     long sleepTime = 10; /* seconds */
     int maxAttempts = 5;
     boolean statsExporterRegistered = false;
@@ -243,18 +237,35 @@ public class AdService {
     logger.info("StackDriver initialization complete.");
   }
 
+  static void initJaeger() {
+    boolean enabled = Boolean.parseBoolean(System.getenv("JAEGER_ENABLED"));
+    if (enabled) {
+      // Register Jaeger Tracing.
+      JaegerTraceExporter.createAndRegister("http://jaeger-collector:14268/api/traces", "adservice");
+      logger.info("Jaeger initialization complete.");
+    } else {
+      logger.info("Jaeger initialization disabled.");
+    }
+  }
+
   /** Main launches the server from the command line. */
   public static void main(String[] args) throws IOException, InterruptedException {
     // Add final keyword to pass checkStyle.
 
+    // Registers all RPC views.
+    RpcViews.registerAllViews();
+
+    // Registers logging trace exporter.
+    LoggingTraceExporter.register();
+
     new Thread( new Runnable() {
       public void run(){
         initStackdriver();
       }
     }).start();
 
-    // Register Prometheus exporters and export metrics to a Prometheus HTTPServer.
-    PrometheusStatsCollector.createAndRegister();
+    // Register Jaeger
+    initJaeger();
 
     // Start the RPC server. You shouldn't see any output from gRPC before this.
     logger.info("AdService starting.");
@@ -262,4 +273,4 @@ public class AdService {
     service.start();
     service.blockUntilShutdown();
   }
-}
+}