Implement local storage emulator support for the Amazon S3 Media module, documentation (Lombiq Technologies: OCORE-153)

src/OrchardCore.Modules/OrchardCore.Media.AmazonS3/AwsStorageOptionsExtension.cs

@@ -2,6 +2,7 @@
 using System.ComponentModel.DataAnnotations;
 using Amazon.Extensions.NETCore.Setup;
 using Amazon.Runtime;
+using Amazon.S3;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.Logging;
 using OrchardCore.Environment.Shell.Configuration;
@@ -20,7 +21,7 @@ public static IEnumerable<ValidationResult> Validate(this AwsStorageOptions opti
 
         if (options.AwsOptions is not null)
         {
-            if (options.AwsOptions.Region is null)
+            if (options.AwsOptions.Region is null && options.AwsOptions.DefaultClientConfig.ServiceURL is null)
             {
                 yield return new ValidationResult(Constants.ValidationMessages.RegionEndpointIsEmpty);
             }
@@ -43,8 +44,9 @@ public static AwsStorageOptions BindConfiguration(this AwsStorageOptions options
 
         try
         {
-            // Binding AWS Options.
-            options.AwsOptions = shellConfiguration.GetAWSOptions("OrchardCore_Media_AmazonS3");
+            // Binding AWS Options. Using the AmazonS3Config type parameter is necessary to be able to configure
+            // S3-specific properties like ForcePathStyle via the configuration provider.
+            options.AwsOptions = shellConfiguration.GetAWSOptions<AmazonS3Config>("OrchardCore_Media_AmazonS3");
 
             // In case Credentials sections was specified, trying to add BasicAWSCredential to AWSOptions
             // since by design GetAWSOptions skips Credential section while parsing config.

src/OrchardCore.Modules/OrchardCore.Media/Controllers/AdminController.cs

@@ -215,7 +215,19 @@ public async Task<IActionResult> Upload(string path, string extensions)
 
                             var mediaFile = await _mediaFileStore.GetFileInfoAsync(mediaFilePath);
 
-                            stream.Position = 0;
+                            // The .NET AWS SDK, and only that from the built-in ones (but others maybe too), disposes
+                            // the stream. There's no better way to check for that than handling the exception. An
+                            // alternative would be to re-read the file for every other storage provider as well but
+                            // that would be wasteful.
+                            try
+                            {
+                                stream.Position = 0;
+                            }
+                            catch (ObjectDisposedException)
+                            {
+                                stream = null;
+                            }
+
                             await PreCacheRemoteMedia(mediaFile, stream);
 
                             result.Add(CreateFileResult(mediaFile));

src/docs/reference/modules/Media.AmazonS3/README.md

@@ -154,6 +154,51 @@ The `BucketName` property and the `BasePath` property are the only templatable p
 }
 ```
 
+## Configuring a Local Emulator
+
+During development, instead of using an online S3 resource, you can use a local storage emulator too. This is especially important for development teams, since you don't want to step on each others' feet by using a shared storage.
+
+For emulators, you'll need to configure a `ServiceURL`. Instead of the default [virtual host addressing of buckets](https://docs.aws.amazon.com/AmazonS3/latest/userguide/VirtualHosting.html), you'll also need to enable path-style addressing (i.e. instead of `http://mybucket.localhost`, the local bucket will be accessible under `http://localhost/mybucket`).
+
+```json
+{
+    "OrchardCore": {
+        "OrchardCore_Media_AmazonS3": {
+            // Note how we use ServiceURL, just with emulators. There should be no Region specified.
+            "ServiceURL": "http://localhost:9444/",
+            "Profile": "default",
+            "ProfilesLocation": "",
+            // Providing some credentials is required but emulators don't actually use them.
+            "Credentials": {
+                "SecretKey": "dummy",
+                "AccessKey": "dummy"
+            },
+            // BasePath and BucketName can be templated too, as usual.
+            "BasePath": "/media",
+            "CreateBucket": true,
+            "RemoveBucket": true,
+            "BucketName": "media",
+            // This is required for all emulators.
+            "ForcePathStyle": true
+        }
+    }
+}
+```
+
+The following tools are known to be working with the above settings. Be sure to explore further configuration of these tools, the commands below are just provided for your convenience as a general recommendation.
+
+- [LocalS3](https://github.com/Robothy/local-s3) with Docker:
+
+```
+docker run -d -e MODE=IN_MEMORY -p 9444:80 luofuxiang/local-s3
+```
+
+- [S3Mock](https://github.com/adobe/S3Mock) with Docker:
+
+```
+docker run -p 9444:9090 -t adobe/s3mock
+```
+
 ## Media Cache
 
 The Media Cache feature will automatically be enabled when Amazon Media Storage is enabled.