Add referrer with annotations for image source and base image name + digest

src/ImageBuilder/Commands/Build/ImageArtifactDetailsExtensions.cs

@@ -0,0 +1,26 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Collections.Generic;
+using System.Linq;
+using Microsoft.DotNet.ImageBuilder.Models.Image;
+
+namespace Microsoft.DotNet.ImageBuilder.Commands.Build;
+
+/// <summary>
+/// Extension methods for image artifact details used during build command processing.
+/// </summary>
+internal static class ImageArtifactDetailsExtensions
+{
+    /// <summary>
+    /// Enumerates all platform data entries from image-info repo and image groups.
+    /// </summary>
+    /// <param name="imageArtifactDetails">The image artifact details to enumerate.</param>
+    /// <returns>All platform data entries contained in the image artifact details.</returns>
+    internal static IEnumerable<PlatformData> EnumeratePlatforms(this ImageArtifactDetails imageArtifactDetails) =>
+        imageArtifactDetails.Repos
+            .Where(repoData => repoData.Images != null)
+            .SelectMany(repoData => repoData.Images)
+            .SelectMany(imageData => imageData.Platforms);
+}

src/ImageBuilder/GitHelper.cs

@@ -24,31 +24,36 @@ public static class GitHelper
 
         public static string GetCommitSha(string filePath, bool useFullHash = false)
         {
-            // Don't make the assumption that the current working directory is a Git repository
-            // Find the Git repo that contains the file being checked.
-            DirectoryInfo directory = new FileInfo(filePath).Directory;
-            while (!directory.GetDirectories(".git").Any())
-            {
-                directory = directory.Parent;
-
-                if (directory is null)
-                {
-                    throw new InvalidOperationException($"File '{filePath}' is not contained within a Git repository.");
-                }
-            }
-
-            filePath = Path.GetRelativePath(directory.FullName, filePath);
+            string repoRoot = GetRepoRoot(filePath);
+            filePath = Path.GetRelativePath(repoRoot, filePath);
 
             string format = useFullHash ? "H" : "h";
             return ExecuteHelper.Execute(
                 new ProcessStartInfo("git", $"log -1 --format=format:%{format} {filePath}")
                 {
-                    WorkingDirectory = directory.FullName
+                    WorkingDirectory = repoRoot
                 },
                 false,
                 $"Unable to retrieve the latest commit SHA for {filePath}");
         }
 
+        // Don't make the assumption that the current working directory is a Git repository.
+        // Walk up from the given path to find the root of the containing Git repository.
+        public static string GetRepoRoot(string path)
+        {
+            DirectoryInfo directory = Directory.Exists(path) ? new DirectoryInfo(path) : new FileInfo(path).Directory;
+
+            // The repository root is marked by a ".git" entry. It's a directory in a normal
+            // checkout, but a file (a gitdir pointer) in linked worktrees and submodules.
+            while (!directory.EnumerateFileSystemInfos(".git").Any())
+            {
+                directory = directory.Parent
+                    ?? throw new InvalidOperationException($"'{path}' is not contained within a Git repository.");
+            }
+
+            return directory.FullName;
+        }
+
         public static Uri GetArchiveUrl(IGitHubBranchRef branchRef) =>
             new Uri($"https://github.com/{branchRef.Owner}/{branchRef.Repo}/archive/{branchRef.Branch}.zip");
 

src/ImageBuilder/GitService.cs

@@ -16,6 +16,9 @@ public string GetCommitSha(string filePath, bool useFullHash = false)
             return GitHelper.GetCommitSha(filePath, useFullHash);
         }
 
+        /// <inheritdoc/>
+        public string GetRepoRoot(string path) => GitHelper.GetRepoRoot(path);
+
         public IRepository CloneRepository(string sourceUrl, string workdirPath, CloneOptions options)
         {
             _logger.LogInformation($"Cloning repository {sourceUrl} to {workdirPath}");

src/ImageBuilder/IGitService.cs

@@ -10,6 +10,15 @@ public interface IGitService
     {
         string GetCommitSha(string filePath, bool useFullHash = false);
 
+        /// <summary>
+        /// Gets the absolute path to the root of the Git repository that contains the given path.
+        /// </summary>
+        /// <param name="path">
+        /// An absolute path to a file or directory that resides within a Git repository's working tree.
+        /// </param>
+        /// <returns>The absolute path to the containing repository's root directory.</returns>
+        string GetRepoRoot(string path);
+
         IRepository CloneRepository(string sourceUrl, string workdirPath, CloneOptions options);
 
         void Stage(IRepository repository, string path);

src/ImageBuilder/ImageBuilderAnnotations.cs

@@ -0,0 +1,42 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+namespace Microsoft.DotNet.ImageBuilder;
+
+/// <summary>
+/// Annotation keys, in ImageBuilder's own namespace, that describe how the subject image was built.
+/// These are recorded on the image's referrer artifact.
+/// </summary>
+/// <remarks>
+/// Standard <c>org.opencontainers.image.*</c> annotations are deliberately not used here because OCI
+/// annotations describe the artifact they are placed on. On a referrer artifact they would describe the
+/// referrer itself rather than the subject image, so a custom namespace is used to describe the subject.
+/// </remarks>
+public static class ImageBuilderAnnotations
+{
+    /// <summary>
+    /// URL of the source code repository the image was built from.
+    /// </summary>
+    public const string Source = "vnd.microsoft.imagebuilder.source";
+
+    /// <summary>
+    /// Source control revision (commit) the image was built from.
+    /// </summary>
+    public const string Revision = "vnd.microsoft.imagebuilder.revision";
+
+    /// <summary>
+    /// Path of the Dockerfile the image was built from, relative to the root of the source repository.
+    /// </summary>
+    public const string Dockerfile = "vnd.microsoft.imagebuilder.dockerfile";
+
+    /// <summary>
+    /// Image reference of the base image the image was built from.
+    /// </summary>
+    public const string BaseName = "vnd.microsoft.imagebuilder.base.name";
+
+    /// <summary>
+    /// Digest of the base image the image was built from.
+    /// </summary>
+    public const string BaseDigest = "vnd.microsoft.imagebuilder.base.digest";
+}

src/ImageBuilder/Oras/OciArtifactType.cs

@@ -9,6 +9,11 @@ namespace Microsoft.DotNet.ImageBuilder.Oras;
 /// </summary>
 public static class OciArtifactType
 {
+    /// <summary>
+    /// ImageBuilder metadata referrer for image build information stored in manifest annotations.
+    /// </summary>
+    public const string ImageInfo = "application/vnd.microsoft.imagebuilder.image-info.v1";
+
     /// <summary>
     /// Notary v2 signature envelope.
     /// </summary>