UserAgent: Adds flag to user agent to show if region failover is configured

Microsoft.Azure.Cosmos/src/CosmosClientOptions.cs

@@ -828,21 +828,42 @@ internal void SetUserAgentFeatures(UserAgentContainer userAgent)
                 features |= CosmosClientOptionsFeatures.HttpClientFactory;
             }
 
+            string featureString = null;
             if (features != CosmosClientOptionsFeatures.NoFeatures)
             {
-                string featureString = Convert.ToString((int)features, 2).PadLeft(8, '0');
-                if (!string.IsNullOrEmpty(featureString))
-                {
-                    userAgent.SetFeatures(featureString);
-                }
+                featureString = Convert.ToString((int)features, 2).PadLeft(8, '0');
             }
 
+            string regionConfiguration = this.GetRegionConfiguration();
+            userAgent.SetFeatures(featureString, regionConfiguration);
+
             if (!string.IsNullOrEmpty(this.ApplicationName))
             {
                 userAgent.Suffix = this.ApplicationName;
             }
         }
 
+        /// <summary>
+        /// This generates a key that added to the user agent to make it 
+        /// possible to determine if the SDK has region failover enabled.
+        /// </summary>
+        /// <returns>Format Reg-{D (Disabled discovery)}-S(application region)|L(List of preferred regions)|N(None, user did not configure it)</returns>
+        private string GetRegionConfiguration()
+        {
+            string regionConfig = this.LimitToEndpoint ? "D" : string.Empty;
+            if (!string.IsNullOrEmpty(this.ApplicationRegion))
+            {
+                return regionConfig + "S";
+            }
+
+            if (this.ApplicationPreferredRegions != null)
+            {
+                return regionConfig + "L";
+            }
+
+            return regionConfig + "N";
+        }
+
         /// <summary>
         /// Serialize the current configuration into a JSON string
         /// </summary>

Microsoft.Azure.Cosmos/src/UserAgentContainer.cs

@@ -31,10 +31,14 @@ internal override string BaseUserAgent
             }
         }
 
-        internal void SetFeatures(string features)
+        internal void SetFeatures(
+            string features,
+            string regionConfiguration)
         {
             // Regenerate base user agent to account for features
-            this.cosmosBaseUserAgent = this.CreateBaseUserAgentString(features);
+            this.cosmosBaseUserAgent = this.CreateBaseUserAgentString(
+                features: features,
+                regionConfiguration: regionConfiguration);
             this.Suffix = string.Empty;
         }
 
@@ -55,7 +59,9 @@ protected virtual void GetEnvironmentInformation(
             runtimeFramework = environmentInformation.RuntimeFramework;
         }
 
-        private string CreateBaseUserAgentString(string features = null)
+        private string CreateBaseUserAgentString(
+            string features = null,
+            string regionConfiguration = null)
         {
             this.GetEnvironmentInformation(
                 out string clientVersion,
@@ -74,6 +80,11 @@ private string CreateBaseUserAgentString(string features = null)
             // Do not change the cosmos-netstandard-sdk as it is required for reporting
             string baseUserAgent = $"cosmos-netstandard-sdk/{clientVersion}" + Regex.Replace($"|{directVersion}|{clientId}|{processArchitecture}|{operatingSystem}|{runtimeFramework}|", @"[^0-9a-zA-Z\.\|\-]+", " ");
 
+            if (!string.IsNullOrEmpty(regionConfiguration))
+            {
+                baseUserAgent += $"{regionConfiguration}|";
+            }
+
             if (!string.IsNullOrEmpty(features))
             {
                 baseUserAgent += $"F {features}|";

Microsoft.Azure.Cosmos/tests/Microsoft.Azure.Cosmos.EmulatorTests/UserAgentTests.cs

@@ -96,6 +96,105 @@ public void VerifyUserAgentContent()
             Assert.AreEqual(envInfo.RuntimeFramework, values[5]);
         }
 
+        [TestMethod]
+        public async Task VerifyUserAgentWithRegionConfiguration()
+        {
+            string databaseName = Guid.NewGuid().ToString();
+            string containerName = Guid.NewGuid().ToString();
+
+            {
+                CosmosClientOptions cosmosClientOptions = new CosmosClientOptions();
+
+                // N - None. The user did not configure anything
+                string userAgentContentToValidate = "|N|";
+                await this.ValidateUserAgentStringAsync(
+                    cosmosClientOptions,
+                    userAgentContentToValidate,
+                    databaseName,
+                    containerName);
+            }
+
+            {
+                CosmosClientOptions cosmosClientOptions = new CosmosClientOptions
+                {
+                    LimitToEndpoint = true
+                };
+                // D - Disabled endpoint discovery, N - None. The user did not configure anything
+                string userAgentContentToValidate = "|DN|";
+                await this.ValidateUserAgentStringAsync(
+                    cosmosClientOptions,
+                    userAgentContentToValidate,
+                    databaseName,
+                    containerName);
+            }
+
+            {
+                CosmosClientOptions cosmosClientOptions = new CosmosClientOptions
+                {
+                    ApplicationRegion = Regions.EastUS
+                };
+
+                // S - Single application region is set
+                string userAgentContentToValidate = "|S|";
+                await this.ValidateUserAgentStringAsync(
+                    cosmosClientOptions,
+                    userAgentContentToValidate,
+                    databaseName,
+                    containerName);
+            }
+
+            {
+                CosmosClientOptions cosmosClientOptions = new CosmosClientOptions
+                {
+                    LimitToEndpoint = false,
+                    ApplicationRegion = null,
+                    ApplicationPreferredRegions = new List<string>()
+                    {
+                        Regions.EastUS,
+                        Regions.WestUS
+                    }
+                };
+
+                // L - List of region is set
+                string userAgentContentToValidate = "|L|";
+                await this.ValidateUserAgentStringAsync(
+                    cosmosClientOptions,
+                    userAgentContentToValidate,
+                    databaseName,
+                    containerName);
+            }
+
+            using (CosmosClient client = TestCommon.CreateCosmosClient())
+            {
+                await client.GetDatabase(databaseName).DeleteStreamAsync();
+            }
+        }
+
+        private async Task ValidateUserAgentStringAsync(
+            CosmosClientOptions cosmosClientOptions,
+            string userAgentContentToValidate,
+            string databaseName,
+            string containerName)
+        {
+            HttpClientHandlerHelper httpClientHandlerHelper = new HttpClientHandlerHelper()
+            {
+                RequestCallBack = (request, cancellationToken) =>
+                {
+                    string userAgent = request.Headers.UserAgent.ToString();
+                    Assert.IsTrue(userAgent.Contains(userAgentContentToValidate));
+                    return null;
+                }
+            };
+
+            cosmosClientOptions.HttpClientFactory = () => new HttpClient(httpClientHandlerHelper);
+
+            using (CosmosClient client = TestCommon.CreateCosmosClient(cosmosClientOptions))
+            {
+                Cosmos.Database db = await client.CreateDatabaseIfNotExistsAsync(databaseName);
+                await db.CreateContainerIfNotExistsAsync(containerName, "/pk");
+            }
+        }
+
         [TestMethod]
         [DataRow(true, true)]
         [DataRow(true, false)]
@@ -174,7 +273,7 @@ internal override ConnectionPolicy GetConnectionPolicy()
             {
                 ConnectionPolicy connectionPolicy = base.GetConnectionPolicy();
                 MacOsUserAgentContainer userAgent = new MacOsUserAgentContainer();
-                
+
                 this.SetUserAgentFeatures(userAgent);
 
                 connectionPolicy.UserAgentContainer = userAgent;