Shorten the defeult timeout of individual call to backend

Author: RichardChen820

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationOptions.cs

@@ -2,6 +2,7 @@
 // Licensed under the MIT license.
 //
 using Azure.Core;
+using Azure.Core.Pipeline;
 using Azure.Data.AppConfiguration;
 using Microsoft.Extensions.Azure;
 using Microsoft.Extensions.Configuration.AzureAppConfiguration.AzureKeyVault;
@@ -11,6 +12,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Net.Http;
 using System.Threading.Tasks;
 
 namespace Microsoft.Extensions.Configuration.AzureAppConfiguration
@@ -23,6 +25,7 @@ public class AzureAppConfigurationOptions
     {
         private const int MaxRetries = 2;
         private static readonly TimeSpan MaxRetryDelay = TimeSpan.FromMinutes(1);
+        private static readonly TimeSpan NetworkTimeout = TimeSpan.FromSeconds(10);
 
         private List<KeyValueWatcher> _changeWatchers = new List<KeyValueWatcher>();
         private List<KeyValueWatcher> _multiKeyWatchers = new List<KeyValueWatcher>();
@@ -473,6 +476,10 @@ private static ConfigurationClientOptions GetDefaultClientOptions()
             clientOptions.Retry.MaxDelay = MaxRetryDelay;
             clientOptions.Retry.Mode = RetryMode.Exponential;
             clientOptions.AddPolicy(new UserAgentHeaderPolicy(), HttpPipelinePosition.PerCall);
+            clientOptions.Transport = new HttpClientTransport(new HttpClient()
+            {
+                Timeout = NetworkTimeout
+            });
 
             return clientOptions;
         }

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/AzureAppConfigurationProvider.cs

@@ -1133,6 +1133,13 @@ await ExecuteWithFailOverPolicyAsync<object>(clients, async (client) =>
 
         private bool IsFailOverable(AggregateException ex)
         {
+            TaskCanceledException tce = ex.InnerExceptions?.LastOrDefault(e => e is TaskCanceledException) as TaskCanceledException;
+
+            if (tce != null && tce.InnerException is TimeoutException)
+            {
+                return true;
+            }
+
             RequestFailedException rfe = ex.InnerExceptions?.LastOrDefault(e => e is RequestFailedException) as RequestFailedException;
 
             return rfe != null ? IsFailOverable(rfe) : false;