Advanced Docker Developer Workflows on MacOS X and Windows

Anil Madhavapeddy, Richard Mortier Docker Inc.

OSCON Open Containers Day 2016 with thanks to the Docker for Mac and Windows

teams for extensive contributions.

• All the Linux tools collected in one installer:

• Bundle includes a full VirtualBox installation

• Boot2Docker Virtual Machine

• The Kitematic UI controlled these pieces.

• A relatively loose collection of components:

• Installation and lack of integrated updates caused numerous user issues.

• Performance not ideal due to the layering, especially for file sharing.

• Yet most Docker users use a Mac or Windows host as their development environment.

Docker Toolbox

• Easy drag and drop installation, and autoupdates to get latest Docker.

• Secure, sandboxed virtualisation architecture without elevated privileges.

• Native networking support, with VPN and network sharing compatibility.

• File sharing between container and host: uid mapping, inotify events, etc.

Docker for MacAiming for a native OSX experience that works with existing developer workflows.

Sign up at beta.docker.com

Virtualisation

• Uses the new HyperKit framework, which is in turn based on xHyve and FreeBSD's bHyve.

• Sandbox friendly: processes largely run as non-root, with privileges of the local user.

Virtualisation

• Uses the new HyperKit framework, which is in turn based on xHyve and FreeBSD's bHyve.

• Sandbox friendly: processes largely run as non-root, with privileges of the local user.

Virtualisation

OSX Kernel

Hypervisor.framework

Hardware virt: VMX,

nested paging

• Uses the new HyperKit framework, which is in turn based on xHyve and FreeBSD's bHyve.

• Sandbox friendly: processes largely run as non-root, with privileges of the local user.

Virtualisation

OSX Kernel Userspace

Hypervisor.framework

User Process

Thread/vCPUTraps on I/O pagesManages ACPI, PCI devices

Hardware virt: VMX,

nested paging

• Uses the new HyperKit framework, which is in turn based on xHyve and FreeBSD's bHyve.

• Sandbox friendly: processes largely run as non-root, with privileges of the local user.

Virtualisation

OSX Kernel Userspace

Hypervisor.framework

User ProcessHardware virt: VMX,

nested paging

ProcessLinux Kernel

VirtIO IPCVirtIO BlockVirtIO Net

Alpine Linux Userspace

Latest Docker preconfigured

QCow2VPNKit

Logs redirected to OSX host

• Uses the new HyperKit framework, which is in turn based on xHyve and FreeBSD's bHyve.

• Embeds Linux: includes an embedded lightweight Alpine Linux distribution optimised for fast boot and stateless operation for containers.

Virtualisation

$ docker info Containers: 358 Running: 13 Paused: 0 Stopped: 345 Images: 485 Server Version: 1.11.1 Storage Driver: aufs Root Dir: /var/lib/docker/aufs Backing Filesystem: extfs Dirperm1 Supported: true

Logging Driver: json-file Cgroup Driver: cgroupfs Plugins: Volume: local Network: bridge null host Kernel Version: 4.4.9-moby Operating System: Alpine Linux v3.3 OSType: linux Architecture: x86_64 CPUs: 2 Total Memory: 3.858 GiB

• Uses the new HyperKit framework, which is in turn based on xHyve and FreeBSD's bHyve.

• Sandbox friendly: processes largely run as non-root, with privileges of the local user.

• Embeds Linux: includes an embedded lightweight Alpine Linux distribution optimised for fast boot and stateless operation for containers.

• Drag 'n drop installation: Docker.app is self-contained, installs symlinks from app bundle into /usr/local, and autoupdates.

Virtualisation

• Performance: The CPU performance of a Linux container is largely the same as when running the same compute on the Mac, since we use the hardware CPU virtualisation extensions.

• Battery life: Some battery life hit due to running containers instead of MacOS X native processes, but not adverse for normal use.

• Disk usage: The app manages disk usage via a qcow2 file in its data directory. This is a sparse file that is allocated on demand, up to a (current) maximum of 64GB of disk space. Can be excluded from Time Machine backups.

Virtualisation

NetworkingNotworking

• Want to hide the gory details of virtualisation from the user. The Linux VM should be "invisible".

• Not solving this leads to many user complaints:

• VPN software and corporate installations do not like bridged virtual machines or custom routing.Result: container traffic cannot connect to Internet.

• Services cannot be exposed on localhost or the external interface and are instead on the Linux VM IP address.Result: breaks common web oAuth workflows.

Networking

• Challenge: Deal with custom VPN software on the host that makes it difficult to bridge.

• Solution: VPNKit, efficiently reconstructs container traffic into separate TCP/IP flows and translates them into native OSX/Windows sockets.

OSX Host Linux Host ContainerRUN <...>com.docker.hyperkit-net

Reconstruct traffic

TCP flows

Translate to OSX socket calls

Ethernet bridge

DHCPv4

NTP

Networking

• Challenge: Deal with custom VPN software on the host that makes it difficult to bridge.

• Solution: VPNKit, efficiently reconstructs container traffic into separate TCP/IP flows and translates them into native OSX/Windows sockets.

• Benefits:

• All network traffic is generated from normal socket calls (e.g. gethostbyaddr) on the Mac, so interacts well with firewalls, VPNs, and any local security policies.

Networking

OSX Host Linux Host

Privileged Port Service

Container

EXPOSEPort Service

VSock Binder

RUN <...>

VSock Listener

Userland Proxy

• Challenge: Services publishing ports should be exposed on localhost without needing VM info.

• Solution: VPNKit forwards container port requests to a OSX service which binds them natively on its external interface.

Networking

• Challenge: Services publishing ports should be exposed on localhost without needing VM info.

• Solution: VPNKit forwards container port requests to a OSX service which binds them natively on its external interface.

• Benefits:

• docker run -P on the Mac now works without requiring any knowledge of the VM innards.

• External oAuth workflows operate with web apps.

Networking

Filesystems

• Challenge: Share arbitrary OSX directory tree into Linux container without requiring extensive modification of either side.

• Solution: Use a FUSE forwarding layer and translate Linux filesystem calls to OSX equivalents.

OSX Host Linux Host ContainerVOLUMEcom.docker.osxfs

Track extra metadata

Translate to OSX filesystem calls

FUSE

Filesystem Sharing

• Challenge: Need filesystem activation so events on the Mac wake up container servers and vice-versa.

• Solution: osxfs uses FSEvents API and injects inotify activation events into container.

OSX Host Linux Host ContainerVOLUMEcom.docker.osxfs

FSEvents watches open files

Events from Linux causes OSX apps

to wake up

FUSE

Filesystem Sharing

•New osxfs engine that bind mounts OSX filesystem trees into Docker containers. •Daemon that listens bidirectionally on shared volumes and translates between OSX and Linux. Includes notifications, via FSEvents on Mac and inotify on Linux.

•Runs as user and so cannot access system files on OSX host. Planning to further restrict host access in future.

•Mount points for /Users, /Volumes, /private and /tmp from the Mac exist.

•All requesting processes are treated as owners and group members on all bind mounted resources. User/group changes are persisted but not discriminated on.

Filesystem Sharing

$ docker run resin/armv7hf-debian uname -a

Linux 7ed2fca7a3f0 4.1.12 #1 SMP Tue Jan 12 10:51:00 UTC 2016 armv7l GNU/Linux

$ docker run justincormack/ppc64le-debian uname -a

Linux edd13885f316 4.1.12 #1 SMP Tue Jan 12 10:51:00 UTC 2016 ppc64le GNU/Linux

Multi-CPU architectures

Questions?

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Twitter: @avsm