mirror of
https://github.com/apple/container.git
synced 2026-10-15 02:29:21 +00:00
Danny Canter
061bc0a071
This adds support to LinuxContainer to be able to provide an optional writable layer. This is useful as today the rootfs size is determined by the size of the image block itself which is set in stone at unpack time of the image. This leaves a lot to be desired because a user might want a larger or smaller rootfs size, but it's not configurable on a per container basis because of this. To support this, we can pass an additional writable block device that we can overlayfs with the image contents in the guest. All writes will go to this writable layer, and the rootfs size in the container is now whatever size this writable layer is. The block devices (via our ext4 package, but you could use whatever) are cheap enough to generate on the fly that you can choose whatever size you want easily.
544 lines
20 KiB
Swift
544 lines
20 KiB
Swift
//===----------------------------------------------------------------------===//
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// Copyright © 2025-2026 Apple Inc. and the Containerization project authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//===----------------------------------------------------------------------===//
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#if os(macOS)
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import ContainerizationError
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import ContainerizationEXT4
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import ContainerizationOCI
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import ContainerizationOS
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import Foundation
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import ContainerizationExtras
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import SystemPackage
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import Virtualization
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import vmnet
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/// A manager for creating and running containers.
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/// Supports container networking options.
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public struct ContainerManager: Sendable {
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public let imageStore: ImageStore
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private let vmm: VirtualMachineManager
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private var network: Network?
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private var containerRoot: URL {
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self.imageStore.path.appendingPathComponent("containers")
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}
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/// A network that can allocate and release interfaces for use with containers.
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public protocol Network: Sendable {
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mutating func create(_ id: String) throws -> Interface?
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mutating func release(_ id: String) throws
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}
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/// A network backed by vmnet on macOS.
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@available(macOS 26.0, *)
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public struct VmnetNetwork: Network {
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private var allocator: Allocator
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// `reference` isn't used concurrently.
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nonisolated(unsafe) private let reference: vmnet_network_ref
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/// The IPv4 subnet of this network.
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public let subnet: CIDRv4
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/// The IPv4 gateway address of this network.
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public var ipv4Gateway: IPv4Address {
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subnet.gateway
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}
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struct Allocator: Sendable {
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private let addressAllocator: any AddressAllocator<UInt32>
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private let cidr: CIDRv4
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private var allocations: [String: UInt32]
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init(cidr: CIDRv4) throws {
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self.cidr = cidr
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self.allocations = .init()
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let size = Int(cidr.upper.value - cidr.lower.value - 3)
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self.addressAllocator = try UInt32.rotatingAllocator(
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lower: cidr.lower.value + 2,
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size: UInt32(size)
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)
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}
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mutating func allocate(_ id: String) throws -> CIDRv4 {
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if allocations[id] != nil {
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throw ContainerizationError(.exists, message: "allocation with id \(id) already exists")
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}
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let index = try addressAllocator.allocate()
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allocations[id] = index
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let ip = IPv4Address(index)
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return try CIDRv4(ip, prefix: cidr.prefix)
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}
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mutating func release(_ id: String) throws {
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if let index = self.allocations[id] {
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try addressAllocator.release(index)
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allocations.removeValue(forKey: id)
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}
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}
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}
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/// A network interface supporting the vmnet_network_ref.
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public struct Interface: Containerization.Interface, VZInterface, Sendable {
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public let ipv4Address: CIDRv4
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public let ipv4Gateway: IPv4Address?
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public let macAddress: MACAddress?
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public let mtu: UInt32
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// `reference` isn't used concurrently.
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nonisolated(unsafe) private let reference: vmnet_network_ref
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public init(
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reference: vmnet_network_ref,
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ipv4Address: CIDRv4,
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ipv4Gateway: IPv4Address,
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macAddress: MACAddress? = nil,
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mtu: UInt32 = 1500
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) {
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self.ipv4Address = ipv4Address
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self.ipv4Gateway = ipv4Gateway
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self.macAddress = macAddress
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self.mtu = mtu
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self.reference = reference
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}
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/// Returns the underlying `VZVirtioNetworkDeviceConfiguration`.
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public func device() throws -> VZVirtioNetworkDeviceConfiguration {
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let config = VZVirtioNetworkDeviceConfiguration()
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if let macAddress = self.macAddress {
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guard let mac = VZMACAddress(string: macAddress.description) else {
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throw ContainerizationError(.invalidArgument, message: "invalid mac address \(macAddress)")
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}
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config.macAddress = mac
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}
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config.attachment = VZVmnetNetworkDeviceAttachment(network: self.reference)
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return config
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}
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}
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/// Creates a new network.
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/// - Parameter subnet: The subnet to use for this network.
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public init(subnet: CIDRv4? = nil) throws {
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var status: vmnet_return_t = .VMNET_FAILURE
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guard let config = vmnet_network_configuration_create(.VMNET_SHARED_MODE, &status) else {
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throw ContainerizationError(.unsupported, message: "failed to create vmnet config with status \(status)")
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}
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vmnet_network_configuration_disable_dhcp(config)
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if let subnet {
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try Self.configureSubnet(config, subnet: subnet)
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}
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guard let ref = vmnet_network_create(config, &status), status == .VMNET_SUCCESS else {
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throw ContainerizationError(.unsupported, message: "failed to create vmnet network with status \(status)")
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}
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let cidr = try Self.getSubnet(ref)
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self.allocator = try .init(cidr: cidr)
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self.subnet = cidr
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self.reference = ref
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}
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/// Returns a new interface for use with a container.
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/// - Parameter id: The container ID.
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public mutating func create(_ id: String) throws -> Containerization.Interface? {
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let ipv4Address = try allocator.allocate(id)
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return Self.Interface(
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reference: self.reference,
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ipv4Address: ipv4Address,
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ipv4Gateway: self.ipv4Gateway,
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)
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}
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/// Returns a new interface for use with a container with a custom MTU.
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/// - Parameters:
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/// - id: The container ID.
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/// - mtu: The MTU for the interface.
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public mutating func create(_ id: String, mtu: UInt32) throws -> Containerization.Interface? {
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let ipv4Address = try allocator.allocate(id)
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return Self.Interface(
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reference: self.reference,
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ipv4Address: ipv4Address,
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ipv4Gateway: self.ipv4Gateway,
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mtu: mtu
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)
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}
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/// Performs cleanup of an interface.
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/// - Parameter id: The container ID.
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public mutating func release(_ id: String) throws {
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try allocator.release(id)
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}
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private static func getSubnet(_ ref: vmnet_network_ref) throws -> CIDRv4 {
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var subnet = in_addr()
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var mask = in_addr()
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vmnet_network_get_ipv4_subnet(ref, &subnet, &mask)
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let sa = UInt32(bigEndian: subnet.s_addr)
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let mv = UInt32(bigEndian: mask.s_addr)
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let lower = IPv4Address(sa & mv)
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let upper = IPv4Address(lower.value + ~mv)
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return try CIDRv4(lower: lower, upper: upper)
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}
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private static func configureSubnet(_ config: vmnet_network_configuration_ref, subnet: CIDRv4) throws {
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let gateway = subnet.gateway
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var ga = in_addr()
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inet_pton(AF_INET, gateway.description, &ga)
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let mask = IPv4Address(subnet.prefix.prefixMask32)
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var ma = in_addr()
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inet_pton(AF_INET, mask.description, &ma)
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guard vmnet_network_configuration_set_ipv4_subnet(config, &ga, &ma) == .VMNET_SUCCESS else {
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throw ContainerizationError(.internalError, message: "failed to set subnet \(subnet) for network")
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}
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}
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}
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/// Create a new manager with the provided kernel, initfs mount, image store
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/// and optional network implementation. This will use a Virtualization.framework
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/// backed VMM implicitly.
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public init(
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kernel: Kernel,
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initfs: Mount,
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imageStore: ImageStore,
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network: Network? = nil,
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rosetta: Bool = false,
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nestedVirtualization: Bool = false
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) throws {
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self.imageStore = imageStore
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self.network = network
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try Self.createRootDirectory(path: self.imageStore.path)
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self.vmm = VZVirtualMachineManager(
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kernel: kernel,
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initialFilesystem: initfs,
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rosetta: rosetta,
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nestedVirtualization: nestedVirtualization
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)
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}
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/// Create a new manager with the provided kernel, initfs mount, root state
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/// directory and optional network implementation. This will use a Virtualization.framework
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/// backed VMM implicitly.
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public init(
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kernel: Kernel,
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initfs: Mount,
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root: URL? = nil,
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network: Network? = nil,
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rosetta: Bool = false,
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nestedVirtualization: Bool = false
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) throws {
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if let root {
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self.imageStore = try ImageStore(path: root)
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} else {
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self.imageStore = ImageStore.default
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}
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self.network = network
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try Self.createRootDirectory(path: self.imageStore.path)
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self.vmm = VZVirtualMachineManager(
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kernel: kernel,
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initialFilesystem: initfs,
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rosetta: rosetta,
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nestedVirtualization: nestedVirtualization
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)
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}
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/// Create a new manager with the provided kernel, initfs reference, image store
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/// and optional network implementation. This will use a Virtualization.framework
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/// backed VMM implicitly.
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public init(
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kernel: Kernel,
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initfsReference: String,
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imageStore: ImageStore,
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network: Network? = nil,
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rosetta: Bool = false,
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nestedVirtualization: Bool = false
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) async throws {
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self.imageStore = imageStore
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self.network = network
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try Self.createRootDirectory(path: self.imageStore.path)
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let initPath = self.imageStore.path.appendingPathComponent("initfs.ext4")
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let initImage = try await self.imageStore.getInitImage(reference: initfsReference)
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let initfs = try await {
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do {
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return try await initImage.initBlock(at: initPath, for: .linuxArm)
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} catch let err as ContainerizationError {
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guard err.code == .exists else {
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throw err
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}
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return .block(
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format: "ext4",
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source: initPath.absolutePath(),
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destination: "/",
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options: ["ro"]
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)
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}
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}()
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self.vmm = VZVirtualMachineManager(
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kernel: kernel,
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initialFilesystem: initfs,
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rosetta: rosetta,
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nestedVirtualization: nestedVirtualization
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)
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}
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/// Create a new manager with the provided kernel and image reference for the initfs.
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/// This will use a Virtualization.framework backed VMM implicitly.
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public init(
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kernel: Kernel,
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initfsReference: String,
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root: URL? = nil,
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network: Network? = nil,
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rosetta: Bool = false,
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nestedVirtualization: Bool = false
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) async throws {
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if let root {
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self.imageStore = try ImageStore(path: root)
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} else {
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self.imageStore = ImageStore.default
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}
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self.network = network
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try Self.createRootDirectory(path: self.imageStore.path)
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let initPath = self.imageStore.path.appendingPathComponent("initfs.ext4")
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let initImage = try await self.imageStore.getInitImage(reference: initfsReference)
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let initfs = try await {
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do {
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return try await initImage.initBlock(at: initPath, for: .linuxArm)
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} catch let err as ContainerizationError {
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guard err.code == .exists else {
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throw err
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}
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return .block(
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format: "ext4",
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source: initPath.absolutePath(),
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destination: "/",
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options: ["ro"]
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)
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}
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}()
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self.vmm = VZVirtualMachineManager(
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kernel: kernel,
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initialFilesystem: initfs,
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rosetta: rosetta,
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nestedVirtualization: nestedVirtualization
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)
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}
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/// Create a new manager with the provided vmm and network.
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public init(
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vmm: any VirtualMachineManager,
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network: Network? = nil
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) throws {
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self.imageStore = ImageStore.default
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try Self.createRootDirectory(path: self.imageStore.path)
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self.network = network
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self.vmm = vmm
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}
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private static func createRootDirectory(path: URL) throws {
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try FileManager.default.createDirectory(
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at: path.appendingPathComponent("containers"),
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withIntermediateDirectories: true
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)
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}
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/// Returns a new container from the provided image reference.
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/// - Parameters:
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/// - id: The container ID.
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/// - reference: The image reference.
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/// - rootfsSizeInBytes: The size of the root filesystem in bytes. Defaults to 8 GiB.
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/// - writableLayerSizeInBytes: Optional size for a separate writable layer. When provided,
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/// the rootfs becomes read-only and an overlayfs is used with a separate writable layer of this size.
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/// - readOnly: Whether to mount the root filesystem as read-only.
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public mutating func create(
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_ id: String,
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reference: String,
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rootfsSizeInBytes: UInt64 = 8.gib(),
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writableLayerSizeInBytes: UInt64? = nil,
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readOnly: Bool = false,
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configuration: (inout LinuxContainer.Configuration) throws -> Void
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) async throws -> LinuxContainer {
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let image = try await imageStore.get(reference: reference, pull: true)
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return try await create(
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id,
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image: image,
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rootfsSizeInBytes: rootfsSizeInBytes,
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writableLayerSizeInBytes: writableLayerSizeInBytes,
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readOnly: readOnly,
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configuration: configuration
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)
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}
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/// Returns a new container from the provided image.
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/// - Parameters:
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/// - id: The container ID.
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/// - image: The image.
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/// - rootfsSizeInBytes: The size of the root filesystem in bytes. Defaults to 8 GiB.
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/// - writableLayerSizeInBytes: Optional size for a separate writable layer. When provided,
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/// the rootfs becomes read-only and an overlayfs is used with a separate writable layer of this size.
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/// - readOnly: Whether to mount the root filesystem as read-only.
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public mutating func create(
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_ id: String,
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image: Image,
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rootfsSizeInBytes: UInt64 = 8.gib(),
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writableLayerSizeInBytes: UInt64? = nil,
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readOnly: Bool = false,
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configuration: (inout LinuxContainer.Configuration) throws -> Void
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) async throws -> LinuxContainer {
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let path = try createContainerRoot(id)
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var rootfs = try await unpack(
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image: image,
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destination: path.appendingPathComponent("rootfs.ext4"),
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size: rootfsSizeInBytes
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)
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if readOnly {
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rootfs.options.append("ro")
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}
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// Create writable layer if size is specified.
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var writableLayer: Mount? = nil
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if let writableLayerSize = writableLayerSizeInBytes {
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writableLayer = try createEmptyFilesystem(
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at: path.appendingPathComponent("writable.ext4"),
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size: writableLayerSize
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)
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}
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return try await create(
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id,
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image: image,
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rootfs: rootfs,
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writableLayer: writableLayer,
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configuration: configuration
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)
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}
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/// Returns a new container from the provided image and root filesystem mount.
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/// - Parameters:
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/// - id: The container ID.
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/// - image: The image.
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/// - rootfs: The root filesystem mount pointing to an existing block file.
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/// The `destination` field is ignored as mounting is handled internally.
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/// - writableLayer: Optional writable layer mount. When provided, an overlayfs is used with
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/// rootfs as the lower layer and this as the upper layer.
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/// The `destination` field is ignored as mounting is handled internally.
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public mutating func create(
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_ id: String,
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image: Image,
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rootfs: Mount,
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writableLayer: Mount? = nil,
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configuration: (inout LinuxContainer.Configuration) throws -> Void
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) async throws -> LinuxContainer {
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let imageConfig = try await image.config(for: .current).config
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return try LinuxContainer(
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id,
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rootfs: rootfs,
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writableLayer: writableLayer,
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vmm: self.vmm
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) { config in
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if let imageConfig {
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config.process = .init(from: imageConfig)
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}
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if let interface = try self.network?.create(id) {
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config.interfaces = [interface]
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guard let gateway = interface.ipv4Gateway else {
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throw ContainerizationError(
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.invalidState,
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message: "missing ipv4 gateway for container \(id)"
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)
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}
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config.dns = .init(nameservers: [gateway.description])
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}
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config.bootLog = BootLog.file(path: self.containerRoot.appendingPathComponent(id).appendingPathComponent("bootlog.log"))
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try configuration(&config)
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}
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}
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|
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/// Releases network resources for a container.
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///
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/// - Parameter id: The container ID.
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public mutating func releaseNetwork(_ id: String) throws {
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try self.network?.release(id)
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}
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/// Releases network resources and removes all files for a container.
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/// - Parameter id: The container ID.
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public mutating func delete(_ id: String) throws {
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try self.releaseNetwork(id)
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let path = containerRoot.appendingPathComponent(id)
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try FileManager.default.removeItem(at: path)
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}
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private func createContainerRoot(_ id: String) throws -> URL {
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let path = containerRoot.appendingPathComponent(id)
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try FileManager.default.createDirectory(at: path, withIntermediateDirectories: false)
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return path
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}
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private func unpack(image: Image, destination: URL, size: UInt64) async throws -> Mount {
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do {
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let unpacker = EXT4Unpacker(blockSizeInBytes: size)
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return try await unpacker.unpack(image, for: .current, at: destination)
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} catch let err as ContainerizationError {
|
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if err.code == .exists {
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return .block(
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format: "ext4",
|
|
source: destination.absolutePath(),
|
|
destination: "/",
|
|
options: []
|
|
)
|
|
}
|
|
throw err
|
|
}
|
|
}
|
|
|
|
private func createEmptyFilesystem(at destination: URL, size: UInt64) throws -> Mount {
|
|
let path = destination.absolutePath()
|
|
guard !FileManager.default.fileExists(atPath: path) else {
|
|
throw ContainerizationError(.exists, message: "filesystem already exists at \(path)")
|
|
}
|
|
let filesystem = try EXT4.Formatter(FilePath(path), minDiskSize: size)
|
|
try filesystem.close()
|
|
return .block(
|
|
format: "ext4",
|
|
source: path,
|
|
destination: "/",
|
|
options: []
|
|
)
|
|
}
|
|
}
|
|
|
|
extension CIDRv4 {
|
|
/// The gateway address of the network.
|
|
public var gateway: IPv4Address {
|
|
IPv4Address(self.lower.value + 1)
|
|
}
|
|
}
|
|
|
|
#endif
|