[Azure] Support raw connection strings for Azure Blob Storage (loic-s…

…harma#411)

Addresses loic-sharma#394

docs/quickstart/azure.md

@@ -42,9 +42,14 @@ Update the `appsettings.json` file:
 
     "Storage": {
         "Type": "AzureBlobStorage",
+
         "AccountName": "my-account",
-        "Container": "my-container",
-        "AccessKey": "abcd1234"
+        "AccessKey": "abcd1234",
+        "Container": "my-container"
+
+        // You can also use a connection string:
+        // "ConnectionString": "AccountName=my-account;AccountKey=abcd1234;...",
+        // "Container": "my-container"
     },
 
     ...

src/BaGet.Azure/Configuration/BlobStorageOptions.cs

@@ -1,16 +1,62 @@
-using System.ComponentModel.DataAnnotations;
+using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations;
 
 namespace BaGet.Azure.Configuration
 {
-    public class BlobStorageOptions
+    /// <summary>
+    /// BaGet's configurations to use Azure Blob Storage to store packages.
+    /// See: https://loic-sharma.github.io/BaGet/quickstart/azure/#azure-blob-storage
+    /// </summary>
+    public class BlobStorageOptions : IValidatableObject
     {
-        [Required]
+        /// <summary>
+        /// The Azure Blob Storage connection string.
+        /// If provided, ignores <see cref="AccountName"/> and <see cref="AccessKey"/>.
+        /// </summary>
+        public string ConnectionString { get; set; }
+
+        /// <summary>
+        /// The Azure Blob Storage account name. Ignored if <see cref="ConnectionString"/> is provided.
+        /// </summary>
         public string AccountName { get; set; }
-
-        [Required]
+
+        /// <summary>
+        /// The Azure Blob Storage access key. Ignored if <see cref="ConnectionString"/> is provided.
+        /// </summary>        
         public string AccessKey { get; set; }
 
-        [Required]
+        /// <summary>
+        /// The Azure Blob Storage container name.
+        /// </summary>
         public string Container { get; set; }
+
+        public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
+        {
+            const string helpUrl = "https://loic-sharma.github.io/BaGet/quickstart/azure/#azure-blob-storage";
+
+            if (string.IsNullOrEmpty(ConnectionString))
+            {
+                if (string.IsNullOrEmpty(AccountName))
+                {
+                    yield return new ValidationResult(
+                        $"The {nameof(AccountName)} configuration is required. See {helpUrl}",
+                        new[] { nameof(AccountName) });
+                }
+
+                if (string.IsNullOrEmpty(AccessKey))
+                {
+                    yield return new ValidationResult(
+                        $"The {nameof(AccessKey)} configuration is required. See {helpUrl}",
+                        new[] { nameof(AccessKey) });
+                }
+            }
+
+            if (string.IsNullOrEmpty(Container))
+            {
+                yield return new ValidationResult(
+                    $"The {nameof(Container)} configuration is required. See {helpUrl}",
+                    new[] { nameof(Container) });
+            }
+        }
     }
 }

src/BaGet.Azure/Extensions/IServiceCollectionExtensions.cs

@@ -43,6 +43,11 @@ public static IServiceCollection AddBlobStorageService(this IServiceCollection s
             {
                 var options = provider.GetRequiredService<IOptions<BlobStorageOptions>>().Value;
 
+                if (!string.IsNullOrEmpty(options.ConnectionString))
+                {
+                    return CloudStorageAccount.Parse(options.ConnectionString);
+                }
+
                 return new CloudStorageAccount(
                     new StorageCredentials(
                         options.AccountName,