Give the users the ability to have control over ConfigurationClient instance(s) used by the provider

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

@@ -0,0 +1,74 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT license.
+//
+using Azure.Core;
+using Azure.Data.AppConfiguration;
+using Microsoft.Extensions.Azure;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace Microsoft.Extensions.Configuration.AzureAppConfiguration
+{
+    internal class AzureAppConfigurationClientFactory : IAzureClientFactory<ConfigurationClient>
+    {
+        private readonly ConfigurationClientOptions _clientOptions;
+
+        private readonly TokenCredential _credential;
+        private readonly IEnumerable<string> _connectionStrings;
+
+        public AzureAppConfigurationClientFactory(
+            IEnumerable<string> connectionStrings,
+            ConfigurationClientOptions clientOptions)
+        {
+            if (connectionStrings == null || !connectionStrings.Any())
+            {
+                throw new ArgumentNullException(nameof(connectionStrings));
+            }
+
+            _connectionStrings = connectionStrings;
+
+            _clientOptions = clientOptions ?? throw new ArgumentNullException(nameof(clientOptions));
+        }
+
+        public AzureAppConfigurationClientFactory(
+            TokenCredential credential,
+            ConfigurationClientOptions clientOptions)
+        {
+            _credential = credential ?? throw new ArgumentNullException(nameof(credential));
+            _clientOptions = clientOptions ?? throw new ArgumentNullException(nameof(clientOptions));
+        }
+
+        public ConfigurationClient CreateClient(string endpoint)
+        {
+            if (string.IsNullOrEmpty(endpoint))
+            {
+                throw new ArgumentNullException(nameof(endpoint));
+            }
+
+            if (!Uri.TryCreate(endpoint, UriKind.Absolute, out Uri uriResult))
+            {
+                throw new ArgumentException("Invalid host URI.");
+            }
+
+            if (_credential != null)
+            {
+                return new ConfigurationClient(uriResult, _credential, _clientOptions);
+            }
+
+            string connectionString = _connectionStrings.FirstOrDefault(cs => ConnectionStringUtils.Parse(cs, ConnectionStringUtils.EndpointSection) == endpoint);
+
+            //
+            // falback to the first connection string
+            if (connectionString == null)
+            {
+                string id = ConnectionStringUtils.Parse(_connectionStrings.First(), ConnectionStringUtils.IdSection);
+                string secret = ConnectionStringUtils.Parse(_connectionStrings.First(), ConnectionStringUtils.SecretSection);
+
+                connectionString = ConnectionStringUtils.Build(uriResult, id, secret);
+            }
+
+            return new ConfigurationClient(connectionString, _clientOptions);
+        }
+    }
+}

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

@@ -3,6 +3,7 @@
 //
 using Azure.Core;
 using Azure.Data.AppConfiguration;
+using Microsoft.Extensions.Azure;
 using Microsoft.Extensions.Configuration.AzureAppConfiguration.AzureKeyVault;
 using Microsoft.Extensions.Configuration.AzureAppConfiguration.Extensions;
 using Microsoft.Extensions.Configuration.AzureAppConfiguration.FeatureManagement;
@@ -131,6 +132,11 @@ internal IEnumerable<IKeyValueAdapter> Adapters
         /// </summary>
         internal StartupOptions Startup { get; set; } = new StartupOptions();
 
+        /// <summary>
+        /// Client factory that is responsible for creating instances of ConfigurationClient.
+        /// </summary>
+        internal IAzureClientFactory<ConfigurationClient> ClientFactory { get; private set; }
+
         /// <summary>
         /// Initializes a new instance of the <see cref="AzureAppConfigurationOptions"/> class.
         /// </summary>
@@ -144,6 +150,17 @@ public AzureAppConfigurationOptions()
             };
         }
 
+        /// <summary>
+        /// Sets the client factory used to create ConfigurationClient instances.
+        /// </summary>
+        /// <param name="factory">The client factory.</param>
+        /// <returns>The current <see cref="AzureAppConfigurationOptions"/> instance.</returns>
+        public AzureAppConfigurationOptions SetClientFactory(IAzureClientFactory<ConfigurationClient> factory)
+        {
+            ClientFactory = factory ?? throw new ArgumentNullException(nameof(factory));
+            return this;
+        }
+
         /// <summary>
         /// Specify what key-values to include in the configuration provider.
         /// <see cref="Select"/> can be called multiple times to include multiple sets of key-values.

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

@@ -1,7 +1,11 @@
 // Copyright (c) Microsoft Corporation.
 // Licensed under the MIT license.
 //
+using Azure.Data.AppConfiguration;
+using Microsoft.Extensions.Azure;
 using System;
+using System.Collections.Generic;
+using System.Linq;
 
 namespace Microsoft.Extensions.Configuration.AzureAppConfiguration
 {
@@ -29,35 +33,33 @@ public IConfigurationProvider Build(IConfigurationBuilder builder)
             try
             {
                 AzureAppConfigurationOptions options = _optionsProvider();
-                IConfigurationClientManager clientManager;
 
                 if (options.ClientManager != null)
                 {
-                    clientManager = options.ClientManager;
+                    return new AzureAppConfigurationProvider(options.ClientManager, options, _optional);
                 }
-                else if (options.ConnectionStrings != null)
+
+                IEnumerable<Uri> endpoints;
+                IAzureClientFactory<ConfigurationClient> clientFactory = options.ClientFactory;
+
+                if (options.ConnectionStrings != null)
                 {
-                    clientManager = new ConfigurationClientManager(
-                        options.ConnectionStrings,
-                        options.ClientOptions,
-                        options.ReplicaDiscoveryEnabled,
-                        options.LoadBalancingEnabled);
+                    endpoints = options.ConnectionStrings.Select(cs => new Uri(ConnectionStringUtils.Parse(cs, ConnectionStringUtils.EndpointSection)));
+
+                    clientFactory ??= new AzureAppConfigurationClientFactory(options.ConnectionStrings, options.ClientOptions);
                 }
                 else if (options.Endpoints != null && options.Credential != null)
                 {
-                    clientManager = new ConfigurationClientManager(
-                        options.Endpoints,
-                        options.Credential,
-                        options.ClientOptions,
-                        options.ReplicaDiscoveryEnabled,
-                        options.LoadBalancingEnabled);
+                    endpoints = options.Endpoints;
+
+                    clientFactory ??= new AzureAppConfigurationClientFactory(options.Credential, options.ClientOptions);
                 }
                 else
                 {
                     throw new ArgumentException($"Please call {nameof(AzureAppConfigurationOptions)}.{nameof(AzureAppConfigurationOptions.Connect)} to specify how to connect to Azure App Configuration.");
                 }
 
-                provider = new AzureAppConfigurationProvider(clientManager, options, _optional);
+                provider = new AzureAppConfigurationProvider(new ConfigurationClientManager(clientFactory, endpoints, options.ReplicaDiscoveryEnabled, options.LoadBalancingEnabled), options, _optional);
             }
             catch (InvalidOperationException ex) // InvalidOperationException is thrown when any problems are found while configuring AzureAppConfigurationOptions or when SDK fails to create a configurationClient.
             {

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

@@ -2,10 +2,10 @@
 // Licensed under the MIT license.
 //
 
-using Azure.Core;
 using Azure.Data.AppConfiguration;
 using DnsClient;
 using DnsClient.Protocol;
+using Microsoft.Extensions.Azure;
 using Microsoft.Extensions.Configuration.AzureAppConfiguration.Extensions;
 using System;
 using System.Collections.Generic;
@@ -26,12 +26,11 @@ namespace Microsoft.Extensions.Configuration.AzureAppConfiguration
     /// </remarks>
     internal class ConfigurationClientManager : IConfigurationClientManager, IDisposable
     {
+        private readonly IAzureClientFactory<ConfigurationClient> _clientFactory;
         private readonly IList<ConfigurationClientWrapper> _clients;
+
         private readonly Uri _endpoint;
-        private readonly string _secret;
-        private readonly string _id;
-        private readonly TokenCredential _credential;
-        private readonly ConfigurationClientOptions _clientOptions;
+
         private readonly bool _replicaDiscoveryEnabled;
         private readonly SrvLookupClient _srvLookupClient;
         private readonly string _validDomain;
@@ -52,61 +51,20 @@ internal class ConfigurationClientManager : IConfigurationClientManager, IDispos
         internal int RefreshClientsCalled { get; set; } = 0;
 
         public ConfigurationClientManager(
-            IEnumerable<string> connectionStrings,
-            ConfigurationClientOptions clientOptions,
-            bool replicaDiscoveryEnabled,
-            bool loadBalancingEnabled)
-        {
-            if (connectionStrings == null || !connectionStrings.Any())
-            {
-                throw new ArgumentNullException(nameof(connectionStrings));
-            }
-
-            string connectionString = connectionStrings.First();
-            _endpoint = new Uri(ConnectionStringUtils.Parse(connectionString, ConnectionStringUtils.EndpointSection));
-            _secret = ConnectionStringUtils.Parse(connectionString, ConnectionStringUtils.SecretSection);
-            _id = ConnectionStringUtils.Parse(connectionString, ConnectionStringUtils.IdSection);
-            _clientOptions = clientOptions;
-            _replicaDiscoveryEnabled = replicaDiscoveryEnabled;
-
-            // If load balancing is enabled, shuffle the passed in connection strings to randomize the endpoint used on startup
-            if (loadBalancingEnabled)
-            {
-                connectionStrings = connectionStrings.ToList().Shuffle();
-            }
-
-            _validDomain = GetValidDomain(_endpoint);
-            _srvLookupClient = new SrvLookupClient();
-
-            _clients = connectionStrings
-                .Select(cs =>
-                {
-                    var endpoint = new Uri(ConnectionStringUtils.Parse(cs, ConnectionStringUtils.EndpointSection));
-                    return new ConfigurationClientWrapper(endpoint, new ConfigurationClient(cs, _clientOptions));
-                })
-                .ToList();
-        }
-
-        public ConfigurationClientManager(
+            IAzureClientFactory<ConfigurationClient> clientFactory,
             IEnumerable<Uri> endpoints,
-            TokenCredential credential,
-            ConfigurationClientOptions clientOptions,
             bool replicaDiscoveryEnabled,
             bool loadBalancingEnabled)
         {
+            _clientFactory = clientFactory ?? throw new ArgumentNullException(nameof(clientFactory));
+
             if (endpoints == null || !endpoints.Any())
             {
                 throw new ArgumentNullException(nameof(endpoints));
             }
 
-            if (credential == null)
-            {
-                throw new ArgumentNullException(nameof(credential));
-            }
-
             _endpoint = endpoints.First();
-            _credential = credential;
-            _clientOptions = clientOptions;
+
             _replicaDiscoveryEnabled = replicaDiscoveryEnabled;
 
             // If load balancing is enabled, shuffle the passed in endpoints to randomize the endpoint used on startup
@@ -119,7 +77,7 @@ public ConfigurationClientManager(
             _srvLookupClient = new SrvLookupClient();
 
             _clients = endpoints
-                .Select(endpoint => new ConfigurationClientWrapper(endpoint, new ConfigurationClient(endpoint, _credential, _clientOptions)))
+                .Select(endpoint => new ConfigurationClientWrapper(endpoint, clientFactory.CreateClient(endpoint.AbsoluteUri)))
                 .ToList();
         }
 
@@ -289,9 +247,7 @@ private async Task RefreshFallbackClients(CancellationToken cancellationToken)
                 {
                     var targetEndpoint = new Uri($"https://{host}");
 
-                    var configClient = _credential == null
-                        ? new ConfigurationClient(ConnectionStringUtils.Build(targetEndpoint, _id, _secret), _clientOptions)
-                        : new ConfigurationClient(targetEndpoint, _credential, _clientOptions);
+                    ConfigurationClient configClient = _clientFactory.CreateClient(targetEndpoint.AbsoluteUri);
 
                     newDynamicClients.Add(new ConfigurationClientWrapper(targetEndpoint, configClient));
                 }

src/Microsoft.Extensions.Configuration.AzureAppConfiguration/Microsoft.Extensions.Configuration.AzureAppConfiguration.csproj

@@ -19,6 +19,7 @@
     <PackageReference Include="Azure.Messaging.EventGrid" Version="4.7.0" />
     <PackageReference Include="Azure.Security.KeyVault.Secrets" Version="4.6.0" />
     <PackageReference Include="DnsClient" Version="1.7.0" />
+    <PackageReference Include="Microsoft.Extensions.Azure" Version="1.7.6" />
     <PackageReference Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="6.0.0" />
     <PackageReference Include="Microsoft.Extensions.Logging" Version="6.0.0" />
     <PackageReference Include="Microsoft.Extensions.Configuration" Version="6.0.1" />

tests/Tests.AzureAppConfiguration/FailoverTests.cs

@@ -268,10 +268,11 @@ public void FailOverTests_AutoFailover()
         [Fact]
         public void FailOverTests_ValidateEndpoints()
         {
+            var clientFactory = new AzureAppConfigurationClientFactory(new DefaultAzureCredential(), new ConfigurationClientOptions());
+
             var configClientManager = new ConfigurationClientManager(
+                clientFactory,
                 new[] { new Uri("https://foobar.azconfig.io") },
-                new DefaultAzureCredential(),
-                new ConfigurationClientOptions(),
                 true,
                 false);
 
@@ -285,9 +286,8 @@ public void FailOverTests_ValidateEndpoints()
             Assert.False(configClientManager.IsValidEndpoint("azure.azconfig.bad.io"));
 
             var configClientManager2 = new ConfigurationClientManager(
+                clientFactory,
                 new[] { new Uri("https://foobar.appconfig.azure.com") },
-                new DefaultAzureCredential(),
-                new ConfigurationClientOptions(),
                 true,
                 false);
 
@@ -301,19 +301,17 @@ public void FailOverTests_ValidateEndpoints()
             Assert.False(configClientManager2.IsValidEndpoint("azure.appconfigbad.azure.com"));
 
             var configClientManager3 = new ConfigurationClientManager(
+                clientFactory,
                 new[] { new Uri("https://foobar.azconfig-test.io") },
-                new DefaultAzureCredential(),
-                new ConfigurationClientOptions(),
                 true,
                 false);
 
             Assert.False(configClientManager3.IsValidEndpoint("azure.azconfig-test.io"));
             Assert.False(configClientManager3.IsValidEndpoint("azure.azconfig.io"));
 
             var configClientManager4 = new ConfigurationClientManager(
+                clientFactory,
                 new[] { new Uri("https://foobar.z1.appconfig-test.azure.com") },
-                new DefaultAzureCredential(),
-                new ConfigurationClientOptions(),
                 true,
                 false);
 
@@ -325,10 +323,11 @@ public void FailOverTests_ValidateEndpoints()
         [Fact]
         public void FailOverTests_GetNoDynamicClient()
         {
+            var clientFactory = new AzureAppConfigurationClientFactory(new DefaultAzureCredential(), new ConfigurationClientOptions());
+
             var configClientManager = new ConfigurationClientManager(
+                clientFactory,
                 new[] { new Uri("https://azure.azconfig.io") },
-                new DefaultAzureCredential(),
-                new ConfigurationClientOptions(),
                 true,
                 false);