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Add unpack strategy to SnapshotStore (#274)

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Define a `UnpackStrategy` function type in the `SnapshotStore` to give
more control over how an image is unpacked.

Previously, we were creating a 512 GB sparse block file for the initial
file system of a container, which is overkill.

With this change, the vminit image is unpacked to a smaller block file,
while container images are unpacked to the 512 GB block

Follows the same pattern as
https://github.com/apple/container/blob/main/Sources/Helpers/RuntimeLinux/RuntimeLinuxHelper.swift#L71

Signed-off-by: Aditya Ramani <a_ramani@apple.com>
This commit is contained in:
Aditya Ramani
2025-07-01 11:22:22 -04:00
committed by GitHub
parent 9a14630623
commit 4bfa6c29ec
4 changed files with 32 additions and 15 deletions
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Sources/Helpers/Images/ImagesHelper.swift
+3 -1
View File
@@ -60,6 +60,8 @@ extension ImagesHelper {
.appendingPathComponent("com.apple.container")
}()
private static let unpackStrategy = SnapshotStore.defaultUnpackStrategy
func run() async throws {
let commandName = ImagesHelper._commandName
let log = setupLogger()
@@ -89,7 +91,7 @@ extension ImagesHelper {
private func initializeImagesService(root: URL, log: Logger, routes: inout [String: XPCServer.RouteHandler]) throws {
let contentStore = RemoteContentStoreClient()
let imageStore = try ImageStore(path: root, contentStore: contentStore)
let snapshotStore = try SnapshotStore(path: root)
let snapshotStore = try SnapshotStore(path: root, unpackStrategy: Self.unpackStrategy, log: log)
let service = try ImagesService(contentStore: contentStore, imageStore: imageStore, snapshotStore: snapshotStore, log: log)
let harness = ImagesServiceHarness(service: service, log: log)
Sources/Services/ContainerImagesService/Server/SnapshotStore.swift
+25 -10
View File
@@ -21,6 +21,7 @@ import ContainerizationExtras
import ContainerizationOCI
import ContainerizationOS
import Foundation
import Logging
import TerminalProgress
public actor SnapshotStore {
@@ -28,14 +29,33 @@ public actor SnapshotStore {
private static let snapshotInfoFileName = "snapshot-info"
private static let ingestDirName = "ingest"
/// Return the Unpacker to use for a given image.
/// If the given platform for the image cannot be unpacked return `nil`.
public typealias UnpackStrategy = @Sendable (Containerization.Image, Platform) async throws -> Unpacker?
public static let defaultUnpackStrategy: UnpackStrategy = { image, platform in
guard platform.os == "linux" else {
return nil
}
var minBlockSize = 512.gib()
if image.reference == ClientDefaults.get(key: .defaultInitImage) {
minBlockSize = 512.mib()
}
return EXT4Unpacker(blockSizeInBytes: minBlockSize)
}
let path: URL
let fm = FileManager.default
let ingestDir: URL
let unpackStrategy: UnpackStrategy
let log: Logger?
public init(path: URL) throws {
public init(path: URL, unpackStrategy: @escaping UnpackStrategy, log: Logger?) throws {
let root = path.appendingPathComponent("snapshots")
self.path = root
self.ingestDir = self.path.appendingPathComponent(Self.ingestDirName)
self.unpackStrategy = unpackStrategy
self.log = log
try self.fm.createDirectory(at: root, withIntermediateDirectories: true)
try self.fm.createDirectory(at: self.ingestDir, withIntermediateDirectories: true)
}
@@ -62,7 +82,8 @@ public actor SnapshotStore {
guard let platform = desc.platform else {
throw ContainerizationError(.internalError, message: "Missing platform for descriptor \(desc.digest)")
}
guard Self.shouldUnpackPlatform(platform) else {
guard let unpacker = try await self.unpackStrategy(image, platform) else {
self.log?.warning("Skipping unpack for \(image.reference) for platform \(platform.description). No unpacker configured.")
continue
}
let currentSubTask = await taskManager.startTask()
@@ -79,7 +100,8 @@ public actor SnapshotStore {
let tempSnapshotPath = tempDir.appendingPathComponent(Self.snapshotFileName, isDirectory: false)
let infoPath = tempDir.appendingPathComponent(Self.snapshotInfoFileName, isDirectory: false)
do {
let mount = try await image.unpack(for: platform, at: tempSnapshotPath, progress: ContainerizationProgressAdapter.handler(from: taskUpdateProgress))
let progress = ContainerizationProgressAdapter.handler(from: taskUpdateProgress)
let mount = try await unpacker.unpack(image, for: platform, at: tempSnapshotPath, progress: progress)
let fs = Filesystem.block(
format: mount.type,
source: self.snapshotPath(desc).absolutePath(),
@@ -186,13 +208,6 @@ public actor SnapshotStore {
try self.fm.createDirectory(at: uniqueDirectoryURL, withIntermediateDirectories: true, attributes: nil)
return uniqueDirectoryURL
}
private static func shouldUnpackPlatform(_ platform: Platform) -> Bool {
guard platform.os == "linux" else {
return false
}
return true
}
}
extension FileManager {