Updating the sample for zipkin exporter to follow quickstart at opencensus.io (#87)

* 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

Author: Simon Zeltser

src/Samples/Program.cs

@@ -13,6 +13,8 @@ class StackdriverOptions
     [Verb("zipkin", HelpText = "Specify the options required to test Zipkin exporter")]
     class ZipkinOptions
     {
+        [Option('u', "uri", HelpText = "Please specify the uri of Zipkin backend", Required = true)]
+        public string Uri { get; set; }
     }
 
     [Verb("appInsights", HelpText = "Specify the options required to test ApplicationInsights")]
@@ -39,7 +41,7 @@ public class Program
         /// Main method - invoke this using command line.
         /// For example:
         /// 
-        /// Samples.dll zipkin
+        /// Samples.dll zipkin http://localhost:9411/api/v2/spans
         /// Sample.dll appInsights
         /// Sample.dll prometheus
         /// </summary>
@@ -48,17 +50,14 @@ public static void Main(string[] args)
         {
             Parser.Default.ParseArguments<ZipkinOptions, ApplicationInsightsOptions, PrometheusOptions, HttpClientOptions, StackdriverOptions>(args)
                 .MapResult(
-                    (ZipkinOptions options) => TestZipkin.Run(),
+                    (ZipkinOptions options) => TestZipkin.Run(options.Uri),
                     (ApplicationInsightsOptions options) => TestApplicationInsights.Run(),
                     (PrometheusOptions options) => TestPrometheus.Run(),
                     (HttpClientOptions options) => TestHttpClient.Run(),
                     (StackdriverOptions options) => TestStackdriver.Run(options.ProjectId),
                     errs => 1);
-                    
-            // TestZipkin.Run();
-            // TestApplicationInsights.Run();
-            // TestPrometheus.Run();
-            // TestHttpClient.Run();
+
+            Console.ReadLine();
         }
     }
 }

src/Samples/TestZipkin.cs

@@ -1,37 +1,84 @@
 namespace Samples
 {
     using System;
+    using System.Collections.Generic;
     using System.Threading;
     using OpenCensus.Exporter.Zipkin;
     using OpenCensus.Trace;
+    using OpenCensus.Trace.Config;
     using OpenCensus.Trace.Sampler;
 
     internal class TestZipkin
     {
-        private static ITracer tracer = Tracing.Tracer;
-
-        internal static object Run()
+        internal static object Run(string zipkinUri)
         {
-            Console.WriteLine("Hello World!");
-
+            // 1. Configure exporter to export traces to Zipkin
             var exporter = new ZipkinTraceExporter(
                 new ZipkinTraceExporterOptions()
                 {
-                    Endpoint = new Uri("https://zipkin.azurewebsites.net/api/v2/spans"),
-                    ServiceName = typeof(Program).Assembly.GetName().Name,
+                    Endpoint = new Uri(zipkinUri),
+                    ServiceName = "tracing-to-zipkin-service",
                 },
                 Tracing.ExportComponent);
             exporter.Start();
 
-            var span = tracer.SpanBuilder("incoming request").SetSampler(Samplers.AlwaysSample).StartScopedSpan();
+            // 2. Configure 100% sample rate for the purposes of the demo
+            ITraceConfig traceConfig = Tracing.TraceConfig;
+            ITraceParams currentConfig = traceConfig.ActiveTraceParams;
+            var newConfig = currentConfig.ToBuilder()
+                .SetSampler(Samplers.AlwaysSample)
+                .Build();
+            traceConfig.UpdateActiveTraceParams(newConfig);
+
+            // 3. Tracer is global singleton. You can register it via dependency injection if it exists
+            // but if not - you can use it as follows:
+            var tracer = Tracing.Tracer;
 
-            Thread.Sleep(TimeSpan.FromSeconds(1));
-            var span2 = tracer.CurrentSpan;
-            span2.End();
+            // 4. Create a scoped span. It will end automatically when using statement ends
+            using (var scope = tracer.SpanBuilder("Main").StartScopedSpan())
+            {
+                Console.WriteLine("About to do a busy work");
+                for (int i = 0; i < 10; i++)
+                {
+                    DoWork(i);
+                }
+            }
 
-            Console.ReadLine();
+            // 5. Gracefully shutdown the exporter so it'll flush queued traces to Zipkin.
+            Tracing.ExportComponent.SpanExporter.Dispose();
 
             return null;
         }
+
+        private static void DoWork(int i)
+        {
+            // 6. Get the global singleton Tracer object
+            ITracer tracer = Tracing.Tracer;
+
+            // 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())
+            {
+                // Simulate some work.
+                ISpan span = tracer.CurrentSpan;
+
+                try
+                {
+                    Console.WriteLine("Doing busy work");
+                    Thread.Sleep(1000);
+                }
+                catch (ArgumentOutOfRangeException e)
+                {
+                    // 6. Set status upon error
+                    span.Status = Status.Internal.WithDescription(e.ToString());
+                }
+
+                // 7. Annotate our span to capture metadata about our operation
+                var attributes = new Dictionary<string, IAttributeValue>();
+                attributes.Add("use", AttributeValue.StringAttributeValue("demo"));
+                span.AddAnnotation("Invoking DoWork", attributes);
+            }
+        }
     }
 }