Telemetry: Fixes Trace error when not using Azure VMs

Microsoft.Azure.Cosmos/src/Telemetry/VmMetadataApiHandler.cs

@@ -45,39 +45,44 @@ internal static void TryInitialize(CosmosHttpClient httpClient)
 
                 VmMetadataApiHandler.isInitialized = true;
 
-                _ = Task.Run(() => MetadataApiCallAsync(httpClient), default)
-                            .ContinueWith(t => DefaultTrace.TraceWarning($"Exception while making metadata call {t.Exception}"),
-                            TaskContinuationOptions.OnlyOnFaulted);
-
+                _ = Task.Run(() => MetadataApiCallAsync(httpClient), default);
             }
+
         }
 
         private static async Task MetadataApiCallAsync(CosmosHttpClient httpClient)
         {
-            DefaultTrace.TraceInformation($"Loading VM Metadata");
-
-            static ValueTask<HttpRequestMessage> CreateRequestMessage()
+            try
             {
-                HttpRequestMessage request = new HttpRequestMessage()
-                {
-                    RequestUri = VmMetadataApiHandler.vmMetadataEndpointUrl,
-                    Method = HttpMethod.Get,
-                };
-                request.Headers.Add("Metadata", "true");
+                DefaultTrace.TraceInformation($"Loading VM Metadata");
 
-                return new ValueTask<HttpRequestMessage>(request);
-            }
+                static ValueTask<HttpRequestMessage> CreateRequestMessage()
+                {
+                    HttpRequestMessage request = new HttpRequestMessage()
+                    {
+                        RequestUri = VmMetadataApiHandler.vmMetadataEndpointUrl,
+                        Method = HttpMethod.Get,
+                    };
+                    request.Headers.Add("Metadata", "true");
+
+                    return new ValueTask<HttpRequestMessage>(request);
+                }
 
-            HttpResponseMessage response = await httpClient
-                .SendHttpAsync(createRequestMessageAsync: CreateRequestMessage,
-                                resourceType: ResourceType.Telemetry,
-                                timeoutPolicy: HttpTimeoutPolicyNoRetry.Instance,
-                                clientSideRequestStatistics: null,
-                                cancellationToken: default);
+                HttpResponseMessage response = await httpClient
+                    .SendHttpAsync(createRequestMessageAsync: CreateRequestMessage,
+                                    resourceType: ResourceType.Telemetry,
+                                    timeoutPolicy: HttpTimeoutPolicyNoRetry.Instance,
+                                    clientSideRequestStatistics: null,
+                                    cancellationToken: default);
 
-            azMetadata = await VmMetadataApiHandler.ProcessResponseAsync(response);
+                azMetadata = await VmMetadataApiHandler.ProcessResponseAsync(response);
 
-            DefaultTrace.TraceInformation($"Succesfully get Instance Metadata Response : {azMetadata.Compute.VMId}");
+                DefaultTrace.TraceInformation($"Succesfully get Instance Metadata Response : {azMetadata.Compute.VMId}");
+            }
+            catch (Exception e)
+            {
+                DefaultTrace.TraceInformation($"Azure Environment metadata information not available. {e.Message}");
+            }
         }
 
         internal static async Task<AzureVMMetadata> ProcessResponseAsync(HttpResponseMessage httpResponseMessage)

Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.Tests/VmMetadataApiHandlerTest.cs

@@ -5,12 +5,14 @@
 namespace Microsoft.Azure.Cosmos
 {
     using System;
+    using System.Diagnostics;
     using System.Net;
     using System.Net.Http;
     using System.Reflection;
     using System.Text;
     using System.Threading;
     using System.Threading.Tasks;
+    using Microsoft.Azure.Cosmos.Core.Trace;
     using Microsoft.Azure.Cosmos.Telemetry;
     using Microsoft.Azure.Cosmos.Tests;
     using Microsoft.VisualStudio.TestTools.UnitTesting;
@@ -103,6 +105,35 @@ public async Task ParseAzureVMMetadataTest()
             Assert.AreEqual("vmId:d0cb93eb-214b-4c2b-bd3d-cc93e90d9efd", metadata.Compute.VMId);
         }
 
+        [TestMethod]
+        public void CatchMetadataApiCallExceptionTest()
+        {
+            static Task<HttpResponseMessage> sendFunc(HttpRequestMessage request, CancellationToken cancellationToken) { throw new Exception("error while making API call"); };
+
+            HttpMessageHandler messageHandler = new MockMessageHandler(sendFunc);
+            CosmosHttpClient cosmoshttpClient = MockCosmosUtil.CreateCosmosHttpClient(() => new HttpClient(messageHandler));
+
+            string expectedMsg = "Azure Environment metadata information not available.";
+            ManualResetEvent manualResetEvent = new ManualResetEvent(false);
+
+            void TraceHandler(string message)
+            {
+                Console.WriteLine(message);
+                if (message.Contains(expectedMsg))
+                {
+                    manualResetEvent.Set();
+                }
+            }
+
+            DefaultTrace.TraceSource.Listeners.Add(new TestTraceListener { Callback = TraceHandler });
+            DefaultTrace.InitEventListener();
+
+            VmMetadataApiHandler.TryInitialize(cosmoshttpClient);
+
+            int timeout = 30000;
+            Assert.IsTrue(manualResetEvent.WaitOne(timeout));
+        }
+
         private class MockMessageHandler : HttpMessageHandler
         {
             private readonly Func<HttpRequestMessage, CancellationToken, Task<HttpResponseMessage>> sendFunc;
@@ -116,5 +147,19 @@ protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage
                 return await this.sendFunc(request, cancellationToken);
             }
         }
+        private class TestTraceListener : TraceListener
+        {
+            public Action<string> Callback { get; set; }
+            public override bool IsThreadSafe => true;
+            public override void Write(string message)
+            {
+                this.Callback(message);
+            }
+
+            public override void WriteLine(string message)
+            {
+                this.Callback(message);
+            }
+        }
     }
 }