Support standard Azure Function configuration options for managed ide…

…ntity (#433)

* Support configuration of managed identity via Azure Functions configuration section, and replace most  Azure Storage SDK V11 references with the V12 equivalents.

* remove dependency on Microsoft.Azure.Storage.Blob

src/DurableTask.Netherite.AzureFunctions/BlobLogger.cs

@@ -9,9 +9,8 @@ namespace DurableTask.Netherite.AzureFunctions
     using System.IO;
     using System.Threading;
     using System.Threading.Tasks;
-    using Microsoft.Azure.Storage;
-    using Microsoft.Azure.Storage.Blob;
-    using Microsoft.Extensions.Azure;
+    using Azure.Storage.Blobs;
+    using Azure.Storage.Blobs.Specialized;
 
     /// <summary>
     /// A simple utility class for writing text to an append blob in Azure Storage, using a periodic timer.
@@ -20,7 +19,7 @@ namespace DurableTask.Netherite.AzureFunctions
     class BlobLogger
     {
         readonly DateTime starttime;
-        readonly Task<CloudAppendBlob> blob;
+        readonly Task<AppendBlobClient> blob;
         readonly object flushLock = new object();
         readonly object lineLock = new object();
         readonly ConcurrentQueue<MemoryStream> writebackQueue;
@@ -36,14 +35,14 @@ public BlobLogger(ConnectionInfo storageConnection, string hubName, string worke
             this.starttime = DateTime.UtcNow;
 
             this.blob = GetBlobAsync();
-            async Task<CloudAppendBlob> GetBlobAsync()
+            async Task<AppendBlobClient> GetBlobAsync()
             {
-                CloudStorageAccount storageAccount = await storageConnection.GetAzureStorageV11AccountAsync();
-                CloudBlobClient client = storageAccount.CreateCloudBlobClient();
-                CloudBlobContainer container = client.GetContainerReference("logs");
-                container.CreateIfNotExists();
-                var blob = container.GetAppendBlobReference($"{hubName}.{workerId}.{this.starttime:o}.log");
-                await blob.CreateOrReplaceAsync();
+                BlobServiceClient blobServiceClient = storageConnection.GetAzureStorageV12BlobServiceClient(new Azure.Storage.Blobs.BlobClientOptions());
+                BlobContainerClient containerClient = blobServiceClient.GetBlobContainerClient("logs");
+                await containerClient.CreateIfNotExistsAsync();
+                var blob = containerClient.GetAppendBlobClient($"{hubName}.{workerId}.{this.starttime:o}.log");
+                await blob.DeleteIfExistsAsync();
+                await blob.CreateIfNotExistsAsync();
                 return blob;
             }
 
@@ -95,7 +94,7 @@ public void Flush(object ignored)
                     {
                         // save to storage
                         toSave.Seek(0, SeekOrigin.Begin);
-                        this.blob.GetAwaiter().GetResult().AppendFromStream(toSave);
+                        this.blob.GetAwaiter().GetResult().AppendBlock(toSave);
                         toSave.Dispose();
                     }
                 }

src/DurableTask.Netherite.AzureFunctions/ConfigurationSectionBasedConnectionNameResolver.cs

@@ -0,0 +1,153 @@
+namespace DurableTask.Netherite.AzureFunctions
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Security.Cryptography;
+    using System.Text;
+    using Azure.Identity;
+    using Azure.Messaging.EventHubs;
+    using DurableTask.Netherite;
+    using Microsoft.Extensions.Azure;
+    using Microsoft.Extensions.Configuration;
+
+    /// <summary>
+    /// Resolves connections using an AzureComponentFactory and configuration sections.
+    /// </summary>
+    public class ConfigurationSectionBasedConnectionNameResolver : DurableTask.Netherite.ConnectionResolver
+    {
+        readonly AzureComponentFactory componentFactory;
+        readonly IConfiguration configuration;
+
+        public ConfigurationSectionBasedConnectionNameResolver(AzureComponentFactory componentFactory, IConfiguration configuration)
+        {
+            this.componentFactory = componentFactory;
+            this.configuration = configuration;
+        }
+
+        public override void ResolveLayerConfiguration(string connectionName, out StorageChoices storageChoice, out TransportChoices transportChoice)
+        {
+            if (TransportConnectionString.IsPseudoConnectionString(connectionName))
+            {
+                TransportConnectionString.Parse(connectionName, out storageChoice, out transportChoice);
+            }
+            else
+            {
+                IConfigurationSection connectionSection = this.configuration.GetWebJobsConnectionStringSection(connectionName);
+
+                if (TransportConnectionString.IsPseudoConnectionString(connectionSection.Value))
+                {
+                    TransportConnectionString.Parse(connectionSection.Value, out storageChoice, out transportChoice);
+                }
+                else
+                {
+                    // the default settings are Faster and EventHubs
+                    storageChoice = StorageChoices.Faster;
+                    transportChoice = TransportChoices.EventHubs;
+                }
+            }
+        }
+
+        public override ConnectionInfo ResolveConnectionInfo(string taskHub, string connectionName, ResourceType resourceType)
+        {
+            switch (resourceType)
+            {
+                case ResourceType.BlobStorage:
+                case ResourceType.TableStorage:
+                case ResourceType.PageBlobStorage:
+                    return this.ResolveStorageAccountConnection(connectionName, resourceType);
+
+                case ResourceType.EventHubsNamespace:
+                    return this.ResolveEventHubsConnection(connectionName);
+
+                default:
+                    throw new NotSupportedException("unknown resource type");
+            }
+        }
+
+        public ConnectionInfo ResolveStorageAccountConnection(string connectionName, ResourceType resourceType)
+        {
+            IConfigurationSection connectionSection = this.configuration.GetWebJobsConnectionStringSection(connectionName);
+
+            if (!string.IsNullOrWhiteSpace(connectionSection.Value))
+            {
+                // It's a connection string
+                return ConnectionInfo.FromStorageConnectionString(connectionSection.Value, resourceType);
+            }
+
+            // parse some of the relevant fields in the configuration section
+            StorageAccountOptions accountOptions = connectionSection.Get<StorageAccountOptions>();
+
+            var tokenCredential = this.componentFactory.CreateTokenCredential(connectionSection);
+
+            return ConnectionInfo.FromTokenCredentialAndHost(tokenCredential, accountOptions.GetHost(resourceType), resourceType);
+        }
+
+        class StorageAccountOptions
+        {
+            public string AccountName { get; set; }
+
+            public Uri BlobServiceUri { get; set; }
+
+            public Uri TableServiceUri { get; set; }
+
+            public string GetHost(ResourceType resourceType)
+            {
+                switch (resourceType)
+                {
+                    case ResourceType.BlobStorage:
+                    case ResourceType.PageBlobStorage:
+                        return this.BlobServiceUri?.Host ?? $"{this.AccountName}.blob.core.windows.net";
+
+                    case ResourceType.TableStorage:
+                        return this.TableServiceUri?.Host ?? $"{this.AccountName}.table.core.windows.net";
+
+                    default:
+                        throw new NotSupportedException("unknown resource type");
+                }
+            }
+        }
+
+        public ConnectionInfo ResolveEventHubsConnection(string connectionName)
+        {
+            IConfigurationSection connectionSection = this.configuration.GetWebJobsConnectionStringSection(connectionName);
+            if (!connectionSection.Exists())
+            {
+                // A common mistake is for developers to set their `connection` to a full connection string rather
+                // than an informational name. We handle this case specifically, to be helpful, and to avoid leaking secrets in error messages.
+                try
+                {
+                    var properties = EventHubsConnectionStringProperties.Parse(connectionName);
+
+                    // we parsed without exception, so it's a connection string.
+                    // We now throw a descriptive and secret-free exception.
+
+                    throw new NetheriteConfigurationException($"a full event hubs connection string was incorrectly used instead of a connection setting name");
+                }
+                catch (FormatException)
+                {
+                }
+
+                // Not found
+                throw new NetheriteConfigurationException($"EventHub account connection string with name '{connectionName}' does not exist in the settings. " +
+                                                          $"Make sure that it is a defined App Setting.");
+            }
+
+            if (!string.IsNullOrWhiteSpace(connectionSection.Value))
+            {
+                // It's a connection string
+                return ConnectionInfo.FromEventHubsConnectionString(connectionSection.Value);
+            }
+
+            var fullyQualifiedNamespace = connectionSection["fullyQualifiedNamespace"];
+            if (string.IsNullOrWhiteSpace(fullyQualifiedNamespace))
+            {
+                // We could not find the necessary parameter
+                throw new NetheriteConfigurationException($"Configuration for event hubs connection should have a 'fullyQualifiedNamespace' property or be a string representing a connection string.");
+            }
+
+            var tokenCredential = this.componentFactory.CreateTokenCredential(connectionSection);
+
+            return ConnectionInfo.FromTokenCredentialAndHost(tokenCredential, fullyQualifiedNamespace, ResourceType.EventHubsNamespace);
+        }
+    }
+}

src/DurableTask.Netherite.AzureFunctions/LoggerFactoryWrapper.cs

@@ -7,8 +7,6 @@ namespace DurableTask.Netherite.AzureFunctions
     using System;
     using System.IO;
     using System.Threading;
-    using Microsoft.Azure.Storage;
-    using Microsoft.Azure.Storage.Blob;
     using Microsoft.Extensions.Logging;
 
     class LoggerFactoryWrapper : ILoggerFactory

src/DurableTask.Netherite.AzureFunctions/NetheriteProviderFactory.cs

@@ -188,7 +188,7 @@ NetheriteOrchestrationServiceSettings GetNetheriteOrchestrationServiceSettings(s
 
             if (!string.IsNullOrEmpty(connectionName))
             {
-                if (this.connectionResolver is NameResolverBasedConnectionNameResolver)
+                if (this.connectionResolver is ConfigurationSectionBasedConnectionNameResolver)
                 {
                     // the application does not define a custom connection resolver.
                     // We split the connection name into two connection names, one for storage and one for event hubs

src/DurableTask.Netherite.AzureFunctions/NetheriteProviderStartup.cs

@@ -19,7 +19,7 @@ public void Configure(IWebJobsBuilder builder)
             // We use the UnambiguousNetheriteProviderFactory class instead of the base NetheriteProviderFactory class
             // to avoid ambiguous constructor errors during DI. More details for this workaround can be found in the UnambiguousNetheriteProviderFactory class.
             builder.Services.AddSingleton<IDurabilityProviderFactory, UnambiguousNetheriteProviderFactory>();
-            builder.Services.TryAddSingleton<ConnectionResolver, NameResolverBasedConnectionNameResolver>();
+            builder.Services.TryAddSingleton<ConnectionResolver, ConfigurationSectionBasedConnectionNameResolver>();
 #else
             builder.Services.AddSingleton<IDurabilityProviderFactory, NetheriteProviderPseudoFactory>();
 #endif

src/DurableTask.Netherite.AzureFunctions/WebJobsConfigurationExtensions.cs

@@ -0,0 +1,52 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+namespace DurableTask.Netherite.AzureFunctions
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Text;
+    using Microsoft.Extensions.Configuration;
+
+    static class WebJobsConfigurationExtensions
+    {
+        const string WebJobsConfigurationSectionName = "AzureWebJobs";
+
+        public static IConfigurationSection GetWebJobsConnectionStringSection(this IConfiguration configuration, string connectionStringName)
+        {
+            // first try prefixing
+            string prefixedConnectionStringName = GetPrefixedConnectionStringName(connectionStringName);
+            IConfigurationSection section = GetConnectionStringOrSetting(configuration, prefixedConnectionStringName);
+
+            if (!section.Exists())
+            {
+                // next try a direct unprefixed lookup
+                section = GetConnectionStringOrSetting(configuration, connectionStringName);
+            }
+
+            return section;
+        }
+
+        public static string GetPrefixedConnectionStringName(string connectionStringName)
+        {
+            return WebJobsConfigurationSectionName + connectionStringName;
+        }
+
+        /// <summary>
+        /// Looks for a connection string by first checking the ConfigurationStrings section, and then the root.
+        /// </summary>
+        /// <param name="configuration">The configuration.</param>
+        /// <param name="connectionName">The connection string key.</param>
+        /// <returns></returns>
+        public static IConfigurationSection GetConnectionStringOrSetting(this IConfiguration configuration, string connectionName)
+        {
+            var connectionStringSection = configuration?.GetSection("ConnectionStrings").GetSection(connectionName);
+
+            if (connectionStringSection.Exists())
+            {
+                return connectionStringSection;
+            }
+            return configuration?.GetSection(connectionName);
+        }
+    }
+}

src/DurableTask.Netherite/Connections/CompatibilityConnectionResolver.cs

@@ -7,7 +7,6 @@ namespace DurableTask.Netherite
     using System.Collections.Generic;
     using System.Data;
     using System.Text;
-    using Microsoft.Azure.Storage;
     using Microsoft.Extensions.Logging.Abstractions;