optimize ParseImages in CreateImageIndex

Author: Surayya Huseyn Zada

src/Containers/Microsoft.NET.Build.Containers/BuiltImage.cs

@@ -16,12 +16,12 @@ internal readonly struct BuiltImage
     /// <summary>
     /// Gets image digest.
     /// </summary>
-    internal required string ImageDigest { get; init; }
+    internal string? ImageDigest { get; init; }
 
     /// <summary>
     /// Gets image SHA.
     /// </summary>
-    internal required string ImageSha { get; init; }
+    internal string? ImageSha { get; init; }
 
     /// <summary>
     /// Gets image manifest.

src/Containers/Microsoft.NET.Build.Containers/LocalDaemons/DockerCli.cs

@@ -311,7 +311,7 @@ private static async Task WriteDockerImageToStreamAsync(
         await WriteImageLayers(writer, image, sourceReference, d => $"{d.Substring("sha256:".Length)}/layer.tar", cancellationToken, layerTarballPaths)
             .ConfigureAwait(false);
 
-        string configTarballPath = $"{image.ImageSha}.json";
+        string configTarballPath = $"{image.ImageSha!}.json";
         await WriteImageConfig(writer, image, configTarballPath, cancellationToken)
             .ConfigureAwait(false);
 
@@ -492,7 +492,7 @@ private static async Task WriteOciImageToBlobs(
         await WriteImageLayers(writer, image, sourceReference, d => $"{_blobsPath}/{d.Substring("sha256:".Length)}", cancellationToken)
             .ConfigureAwait(false);
 
-        await WriteImageConfig(writer, image, $"{_blobsPath}/{image.ImageSha}", cancellationToken)
+        await WriteImageConfig(writer, image, $"{_blobsPath}/{image.ImageSha!}", cancellationToken)
             .ConfigureAwait(false);
 
         await WriteManifestForOciImage(writer, image, cancellationToken)

src/Containers/Microsoft.NET.Build.Containers/Registry/Registry.cs

@@ -595,7 +595,7 @@ private async Task PushAsync(BuiltImage builtImage, SourceImageReference source,
         cancellationToken.ThrowIfCancellationRequested();
         using (MemoryStream stringStream = new MemoryStream(Encoding.UTF8.GetBytes(builtImage.Config)))
         {
-            var configDigest = builtImage.ImageDigest;
+            var configDigest = builtImage.ImageDigest!;
             _logger.LogInformation(Strings.Registry_ConfigUploadStarted, configDigest);
             await UploadBlobAsync(destination.Repository, configDigest, stringStream, cancellationToken).ConfigureAwait(false);
             _logger.LogInformation(Strings.Registry_ConfigUploaded);

src/Containers/Microsoft.NET.Build.Containers/Tasks/CreateImageIndex.cs

@@ -108,19 +108,27 @@ private BuiltImage[] ParseImages(DestinationImageReferenceKind destinationKind)
                 break;
             }
 
-            var manifestV2 = JsonSerializer.Deserialize<ManifestV2>(manifest);
-            if (manifestV2 == null)
-            {
-                Log.LogError(Strings.InvalidImageManifest);
-                break;
-            }
-
-            string imageDigest = manifestV2.Config.digest;
-            string imageSha = DigestUtils.GetShaFromDigest(imageDigest);
-            // We don't need layers for remote registry, as the individual images should be pushed already
-            var layers = destinationKind == DestinationImageReferenceKind.RemoteRegistry ? null : manifestV2.Layers;
             (string architecture, string os) = GetArchitectureAndOsFromConfig(config);
 
+            // We don't need ImageDigest, ImageSha, Layers for remote registry, as the individual images should be pushed already
+            string? imageDigest = null;
+            string? imageSha = null;
+            List<ManifestLayer>? layers = null;
+
+            if (destinationKind == DestinationImageReferenceKind.LocalRegistry)
+            {
+                var manifestV2 = JsonSerializer.Deserialize<ManifestV2>(manifest);
+                if (manifestV2 == null)
+                {
+                    Log.LogError(Strings.InvalidImageManifest);
+                    break;
+                }
+
+                imageDigest = manifestV2.Config.digest;
+                imageSha = DigestUtils.GetShaFromDigest(imageDigest);
+                layers = manifestV2.Layers;
+            }     
+
             images[i] = new BuiltImage()
             {
                 Config = config,

src/Tests/Microsoft.NET.Build.Containers.UnitTests/ImageIndexGeneratorTests.cs

@@ -31,8 +31,6 @@ public void UnsupportedMediaTypeThrows()
             new BuiltImage
             {
                 Config = "",
-                ImageDigest = "",
-                ImageSha = "",
                 Manifest = "",
                 ManifestDigest = "",
                 ManifestMediaType = "unsupported"
@@ -53,17 +51,13 @@ public void ImagesWithMixedMediaTypes(string supportedMediaType)
             new BuiltImage
             {
                 Config = "",
-                ImageDigest = "",
-                ImageSha = "",
                 Manifest = "",
                 ManifestDigest = "",
                 ManifestMediaType = supportedMediaType,
             },
             new BuiltImage
             {
                 Config = "",
-                ImageDigest = "",
-                ImageSha = "",
                 Manifest = "",
                 ManifestDigest = "",
                 ManifestMediaType = "anotherMediaType"
@@ -82,8 +76,6 @@ public void GenerateDockerManifestList()
             new BuiltImage
             {
                 Config = "",
-                ImageDigest = "",
-                ImageSha = "",
                 Manifest = "123",
                 ManifestDigest = "sha256:digest1",
                 ManifestMediaType = SchemaTypes.DockerManifestV2,
@@ -93,8 +85,6 @@ public void GenerateDockerManifestList()
             new BuiltImage
             {
                 Config = "",
-                ImageDigest = "",
-                ImageSha = "",
                 Manifest = "123",
                 ManifestDigest = "sha256:digest2",
                 ManifestMediaType = SchemaTypes.DockerManifestV2,
@@ -116,8 +106,6 @@ public void GenerateOciImageIndex()
             new BuiltImage
             {
                 Config = "",
-                ImageDigest = "",
-                ImageSha = "",
                 Manifest = "123",
                 ManifestDigest = "sha256:digest1",
                 ManifestMediaType = SchemaTypes.OciManifestV1,
@@ -127,8 +115,6 @@ public void GenerateOciImageIndex()
             new BuiltImage
             {
                 Config = "",
-                ImageDigest = "",
-                ImageSha = "",
                 Manifest = "123",
                 ManifestDigest = "sha256:digest2",
                 ManifestMediaType = SchemaTypes.OciManifestV1,