Improvements to Stackdriver Stats Exporter (#101)

* Minor fix - updating zipkin sample so we can execute it from command line

* Fix zipkin sample

* Updated zipkin sample to follow the quickstart of opencensus.io for other languages

* Revert the todo

* Adding support for custom json file specification for obtaining service account credentials in Stackdriver metrics exporter

* Changing Stackdriver sample code for metrics to use sum aggregation instead of distribution

Author: Simon Zeltser

src/OpenCensus.Exporter.Stackdriver/Implementation/MetricsConversions.cs

@@ -222,7 +222,7 @@ public static Metric GetMetric(
             string domain)
         {
             var metric = new Metric();
-            metric.Type = metricDescriptor.Name;
+            metric.Type = metricDescriptor.Type;
 
             IList<ITagKey> columns = view.Columns;
 

src/OpenCensus.Exporter.Stackdriver/Implementation/StackdriverStatsConfiguration.cs

@@ -17,6 +17,7 @@
 namespace OpenCensus.Exporter.Stackdriver.Implementation
 {
     using Google.Api;
+    using Google.Apis.Auth.OAuth2;
     using System;
 
     /// <summary>
@@ -41,6 +42,11 @@ public class StackdriverStatsConfiguration
         /// </summary>
         public string ProjectId { get; set; }
 
+        /// <summary>
+        /// Credential used to authenticate against Google Stackdriver Monitoring APIs
+        /// </summary>
+        public GoogleCredential GoogleCredential { get; set; }
+
         /// <summary>
         /// Monitored Resource associated with metrics collection.
         /// By default, the exporter detects the environment where the export is happening,

src/OpenCensus.Exporter.Stackdriver/Implementation/StackdriverStatsExporter.cs

@@ -19,7 +19,9 @@ namespace OpenCensus.Exporter.Stackdriver.Implementation
     using Google.Api;
     using Google.Api.Gax;
     using Google.Api.Gax.Grpc;
+    using Google.Apis.Auth.OAuth2;
     using Google.Cloud.Monitoring.V3;
+    using Grpc.Auth;
     using Grpc.Core;
     using OpenCensus.Exporter.Stackdriver.Utils;
     using OpenCensus.Stats;
@@ -39,6 +41,7 @@ internal class StackdriverStatsExporter
 
         private readonly Dictionary<IView, MetricDescriptor> metricDescriptors = new Dictionary<IView, MetricDescriptor>(new ViewNameComparer());
         private readonly ProjectName project;
+        private readonly GoogleCredential credential;
         private MetricServiceClient metricServiceClient;
         private CancellationTokenSource tokenSource;
 
@@ -73,8 +76,8 @@ public StackdriverStatsExporter(
            StackdriverStatsConfiguration configuration)
         {
             GaxPreconditions.CheckNotNull(configuration, "configuration");
-            GaxPreconditions.CheckNotNullOrEmpty(configuration.ProjectId, "configuration.ProjectId");
             GaxPreconditions.CheckNotNull(configuration.MonitoredResource, "configuration.MonitoredResource");
+            GaxPreconditions.CheckNotNull(configuration.GoogleCredential, "configuration.GoogleCredential");
             GaxPreconditions.CheckArgument(
                 configuration.ExportInterval != TimeSpan.Zero,
                 paramName: "configuration.ExportInterval", 
@@ -84,6 +87,7 @@ public StackdriverStatsExporter(
             monitoredResource = configuration.MonitoredResource;
             collectionInterval = configuration.ExportInterval;
             project = new ProjectName(configuration.ProjectId);
+            credential = configuration.GoogleCredential;
 
             domain = GetDomain(configuration.MetricNamePrefix);
             displayNamePrefix = GetDisplayNamePrefix(configuration.MetricNamePrefix);
@@ -109,7 +113,7 @@ public void Start()
                 if (!isStarted)
                 {
                     tokenSource = new CancellationTokenSource();
-                    metricServiceClient = CreateMetricServiceClient(tokenSource);
+                    metricServiceClient = CreateMetricServiceClient(credential, tokenSource);
 
                     Task.Factory.StartNew(DoWork, tokenSource.Token);
 
@@ -272,7 +276,7 @@ private void Export()
             }
         }
 
-        private static MetricServiceClient CreateMetricServiceClient(CancellationTokenSource tokenSource)
+        private static MetricServiceClient CreateMetricServiceClient(GoogleCredential credential, CancellationTokenSource tokenSource)
         {
             // Make sure to add Opencensus header to every outgoing call to Stackdriver APIs
             Action<Metadata> addOpencensusHeader = m => m.Add(USER_AGENT_KEY, USER_AGENT);
@@ -283,12 +287,17 @@ private static MetricServiceClient CreateMetricServiceClient(CancellationTokenSo
                 headerMutation: addOpencensusHeader,
                 writeOptions: WriteOptions.Default,
                 propagationToken: null);
+
+            var channel = new Channel(
+                MetricServiceClient.DefaultEndpoint.ToString(),
+                credential.ToChannelCredentials());
+
             var metricServiceSettings = new MetricServiceSettings()
             {
                 CallSettings = callSettings
             };
 
-            return MetricServiceClient.Create(settings: metricServiceSettings);
+            return MetricServiceClient.Create(channel, settings: metricServiceSettings);
         }
 
         private static string GetDomain(string metricNamePrefix)

src/OpenCensus.Exporter.Stackdriver/StackdriverExporter.cs

@@ -17,6 +17,9 @@
 
 namespace OpenCensus.Exporter.Stackdriver
 {
+    using Google.Api.Gax;
+    using Google.Apis.Auth.OAuth2;
+    using Google.Cloud.Monitoring.V3;
     using OpenCensus.Exporter.Stackdriver.Implementation;
     using OpenCensus.Stats;
     using OpenCensus.Trace.Export;
@@ -31,6 +34,7 @@ public class StackdriverExporter
         private readonly IExportComponent exportComponent;
         private readonly IViewManager viewManager;
         private readonly string projectId;
+        private readonly string jsonPath;
         private StackdriverStatsExporter statsExporter;
         private object locker = new object();
         private bool isInitialized = false;
@@ -44,9 +48,27 @@ public class StackdriverExporter
         public StackdriverExporter(
             string projectId,
             IExportComponent exportComponent,
+            IViewManager viewManager) : this(projectId, null, exportComponent, viewManager)
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="StackdriverExporter"/> class.
+        /// </summary>
+        /// <param name="projectId">Google Cloud ProjectId that is used to send data to Stackdriver</param>
+        /// <param name="jsonPath">File path to the json file containing the service credential used to authenticate against Stackdriver APIs</param>
+        /// <param name="exportComponent">Exporter to get traces from</param>
+        /// <param name="viewManager">View manager to get the stats from</param>
+        public StackdriverExporter(
+            string projectId,
+            string jsonPath,
+            IExportComponent exportComponent,
             IViewManager viewManager)
         {
+            GaxPreconditions.CheckNotNullOrEmpty(projectId, "projectId");
+
             this.projectId = projectId;
+            this.jsonPath = jsonPath;
             this.exportComponent = exportComponent;
             this.viewManager = viewManager;
         }
@@ -73,7 +95,10 @@ public void Start()
                 // Register stats(metrics) exporter
                 if (viewManager != null)
                 {
+                    GoogleCredential credential = GetGoogleCredential();
+
                     StackdriverStatsConfiguration statsConfig = StackdriverStatsConfiguration.Default;
+                    statsConfig.GoogleCredential = credential;
                     if (statsConfig.ProjectId != projectId)
                     {
                         statsConfig.ProjectId = projectId;
@@ -115,5 +140,21 @@ public void Stop()
                 isInitialized = false;
             }
         }
+
+        private GoogleCredential GetGoogleCredential()
+        {
+            GoogleCredential credential;
+            if (string.IsNullOrEmpty(jsonPath))
+            {
+                credential = GoogleCredential.GetApplicationDefault();
+            }
+            else
+            {
+                credential = GoogleCredential.FromFile(jsonPath)
+                 .CreateScoped(MetricServiceClient.DefaultScopes);
+            }
+
+            return credential;
+        }
     }
 }

src/Samples/TestStackdriver.cs

@@ -17,19 +17,18 @@ internal class TestStackdriver
         private static ITagger tagger = Tags.Tagger;
 
         private static IStatsRecorder statsRecorder = Stats.StatsRecorder;
-        private static readonly IMeasureDouble VideoSize = MeasureDouble.Create("my_org/measure/video_size2", "size of processed videos", "MiB");
+        private static readonly IMeasureDouble VideoSize = MeasureDouble.Create("my_org/measure/video_size", "size of processed videos", "MiB");
         private static readonly ITagKey FrontendKey = TagKey.Create("my_org/keys/frontend");
 
         private static long MiB = 1 << 20;
 
-        private static readonly IViewName VideoSizeViewName = ViewName.Create("my_org/views/video_size2");
+        private static readonly IViewName VideoSizeViewName = ViewName.Create("my_org/views/video_size");
 
         private static readonly IView VideoSizeView = View.Create(
             name: VideoSizeViewName,
             description: "processed video size over time",
             measure: VideoSize,
-            //aggregation: Sum.Create(),
-            aggregation: Distribution.Create(BucketBoundaries.Create(new List<double> { 0.0, 16.0 * MiB, 256.0 * MiB })),
+            aggregation: Sum.Create(),
             columns: new List<ITagKey>() { FrontendKey });
 
         internal static object Run(string projectId)
@@ -53,14 +52,12 @@ internal static object Run(string projectId)
             {
                 using (var scopedSpan = spanBuilder.StartScopedSpan())
                 {
-                    tracer.CurrentSpan.AddAnnotation("Start processing video.");
-
+                    tracer.CurrentSpan.AddAnnotation("Processing video.");
                     Thread.Sleep(TimeSpan.FromMilliseconds(10));
+
                     statsRecorder.NewMeasureMap()
                         .Put(VideoSize, 25 * MiB)
                         .Record();
-
-                    tracer.CurrentSpan.AddAnnotation("Finished processing video.");
                 }
             }
 

src/Samples/TestZipkin.cs

@@ -58,9 +58,11 @@ private static void DoWork(int i)
             // 7. Start another span. If another span was already started, it'll use that span as the parent span.
             // In this example, the main method already started a span, so that'll be the parent span, and this will be
             // a child span.
-            using (OpenCensus.Common.IScope scope = tracer.SpanBuilder("DoWork").StartScopedSpan(out ISpan span))
+            using (OpenCensus.Common.IScope scope = tracer.SpanBuilder("DoWork").StartScopedSpan())
             {
                 // Simulate some work.
+                ISpan span = tracer.CurrentSpan;
+
                 try
                 {
                     Console.WriteLine("Doing busy work");