ContainerRegistry: Add TarImageDestination

Author: euanh

Sources/ContainerRegistry/TarImageDestination.swift

@@ -0,0 +1,115 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the SwiftContainerPlugin open source project
+//
+// Copyright (c) 2025 Apple Inc. and the SwiftContainerPlugin project authors
+// Licensed under Apache License v2.0
+//
+// See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of SwiftContainerPlugin project authors
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+//===----------------------------------------------------------------------===//
+
+import struct Foundation.Data
+import class Foundation.OutputStream
+import class Foundation.JSONDecoder
+import class Foundation.JSONEncoder
+import Tar
+
+public class TarImageDestination {
+    public var decoder: JSONDecoder
+    var encoder: JSONEncoder
+
+    var archive: Archive
+
+    public init(toStream stream: OutputStream) throws {
+        self.archive = Archive(toStream: stream)
+        self.decoder = JSONDecoder()
+        self.encoder = containerJSONEncoder()
+
+        try archive.appendFile(name: "oci-layout", data: [UInt8](encoder.encode(ImageLayoutHeader())))
+        try archive.appendDirectory(name: "blobs")
+        try archive.appendDirectory(name: "blobs/sha256")
+    }
+}
+
+extension TarImageDestination: ImageDestination {
+    /// Saves a blob of unstructured data to the destination.
+    /// - Parameters:
+    ///   - repository: Name of the destination repository.
+    ///   - mediaType: mediaType field for returned ContentDescriptor.
+    ///       On the wire, all blob uploads are `application/octet-stream'.
+    ///   - data: Object to be uploaded.
+    /// - Returns: An ContentDescriptor object representing the
+    ///            saved blob.
+    /// - Throws: If the blob cannot be encoded or the save fails.
+    public func putBlob(
+        repository: ImageReference.Repository,
+        mediaType: String,
+        data: Data
+    ) async throws -> ContentDescriptor {
+        let digest = ImageReference.Digest(of: Data(data))
+        try archive.appendFile(name: "\(digest.value)", prefix: "blobs/\(digest.algorithm)", data: [UInt8](data))
+        return .init(mediaType: mediaType, digest: "\(digest)", size: Int64(data.count))
+    }
+
+    /// Saves a JSON object to the destination, serialized as an unstructured blob.
+    /// - Parameters:
+    ///   - repository: Name of the destination repository.
+    ///   - mediaType: mediaType field for returned ContentDescriptor.
+    ///       On the wire, all blob uploads are `application/octet-stream'.
+    ///   - data: Object to be uploaded.
+    /// - Returns: An ContentDescriptor object representing the
+    ///            saved blob.
+    /// - Throws: If the blob cannot be encoded or the save fails.
+    public func putBlob<Body: Encodable>(
+        repository: ImageReference.Repository,
+        mediaType: String,
+        data: Body
+    ) async throws -> ContentDescriptor {
+        let encoded = try encoder.encode(data)
+        return try await putBlob(repository: repository, mediaType: mediaType, data: encoded)
+    }
+
+    public func blobExists(
+        repository: ImageReference.Repository,
+        digest: ImageReference.Digest
+    ) async throws -> Bool {
+        false
+    }
+
+    public func putManifest(
+        repository: ImageReference.Repository,
+        reference: (any ImageReference.Reference)?,
+        manifest: ImageManifest
+    ) async throws -> ContentDescriptor {
+        // Manifests are not special in the on-disk representation - they are just stored as blobs
+        try await self.putBlob(
+            repository: repository,
+            mediaType: "application/vnd.oci.image.manifest.v1+json",
+            data: manifest
+        )
+    }
+
+    public func putIndex(
+        repository: ImageReference.Repository,
+        reference: (any ImageReference.Reference)?,
+        index: ImageIndex
+    ) async throws -> ContentDescriptor {
+        // Unlike Manifest, Index is not written as a blob
+        let encoded = try encoder.encode(index)
+        let digest = ImageReference.Digest(of: encoded)
+        let mediaType = index.mediaType ?? "application/vnd.oci.image.index.v1+json"
+
+        try archive.appendFile(name: "index.json", data: [UInt8](encoded))
+
+        try archive.appendFile(name: "\(digest.value)", prefix: "blobs/\(digest.algorithm)", data: [UInt8](encoded))
+        return .init(mediaType: mediaType, digest: "\(digest)", size: Int64(encoded.count))
+    }
+}
+
+struct ImageLayoutHeader: Codable {
+    var imageLayoutVersion: String = "1.0.0"
+}

Sources/Tar/tar.swift

@@ -349,8 +349,8 @@ public struct Archive: ~Copyable {
     var output: OutputStream
 
     /// Creates an empty Archive
-    public init() {
-        output = OutputStream.toMemory()
+    public init(toStream: OutputStream = .toMemory()) {
+        output = toStream
         output.open()
         output.schedule(in: .current, forMode: .default)  // is this needed?
     }

Sources/containertool/containertool.swift

@@ -43,6 +43,9 @@ enum AllowHTTP: String, ExpressibleByArgument, CaseIterable { case source, desti
 
         @Option(help: "The base container image name and optional tag")
         var from: String?
+
+        @Option(name: [.long, .short], help: "File in which the container image should be saved")
+        var output: URL
     }
 
     @OptionGroup(title: "Source and destination repository options")
@@ -203,12 +206,17 @@ enum AllowHTTP: String, ExpressibleByArgument, CaseIterable { case source, desti
             if verbose { log("Connected to source registry: \(baseImage.registry)") }
         }
 
-        let destination = try await RegistryClient(
-            registry: destinationImage.registry,
-            insecure: authenticationOptions.allowInsecureHttp == .destination
-                || authenticationOptions.allowInsecureHttp == .both,
-            auth: .init(username: username, password: password, auth: authProvider)
-        )
+        // let destination = try await RegistryClient(
+        //     registry: destinationImage.registry,
+        //     insecure: authenticationOptions.allowInsecureHttp == .destination
+        //         || authenticationOptions.allowInsecureHttp == .both,
+        //     auth: .init(username: username, password: password, auth: authProvider)
+        // )
+
+        guard let saveStream = OutputStream(url: repositoryOptions.output, append: false) else {
+            fatalError("failed to create tarball")
+        }
+        let destination = try TarImageDestination(toStream: saveStream)
 
         if verbose { log("Connected to destination registry: \(destinationImage.registry)") }
         if verbose { log("Using base image: \(baseImage)") }
@@ -231,3 +239,10 @@ enum AllowHTTP: String, ExpressibleByArgument, CaseIterable { case source, desti
         print(finalImage)
     }
 }
+
+// Parse URL path arguments
+extension Foundation.URL: ArgumentParser.ExpressibleByArgument {
+    public init?(argument: String) {
+        self.init(fileURLWithPath: argument)
+    }
+}