Epic: Linux Containers on Windows (LCOW) #33850
Description
Microsoft is hard at work adding support to run both Windows & Linux containers side by side on the same node with a single Docker daemon. As Linux containers are launched, Hyper-V will be used to boot and run a Linux kernel which will then be used to host the container natively. Because many areas of Docker will require changes to handle running multiple platforms side by side, we'll be using this epic to track the list of PRs and proposals in a single place.
Preview documentation
https://docs.microsoft.com/en-us/virtualization/windowscontainers/deploy-containers/linux-containers
Progress
Required for Docker for Windows - Developer Scenarios
| Status | Description |
|---|---|
| Merged | Store Linux images on Windows & launch Linux containers on Window. Right now, platform switching is done with a system-wide environment variable. Side by side support needs the next item. |
| Merged | Support Linux filesystem operations in single-use VMs instead of reusable ones. This can provide protection in the case where a file parsing bug could lead to a container polluting the filesystem of another container. |
| Merged | Use a single tag store so both Windows & Linux containers can be stored and managed by the same engine |
| Merged | Remote filesystem support needed for docker commit, docker cp, and Dockerfile ADD commands |
| Merged | Support resizing ext4 sandbox VHD instead of defaulting to 20Gb only. |
| Merged | Bind mount support. |
| Merged | New --platform parameter for docker run, docker pull, docker import and docker build to choose between platforms and order of precedence when multiple are supported (Windows & Linux) on the same node. See Proposal #34617 . |
| Merged | Coalesce daemon stores - needed to manage both Windows & Linux containers with the same daemon |
| In progress | Add docker kill -s for signals != SIGKILL. |
| Merged | Support WORKDIR in running existing images and building new ones |
| Not started | Add platform filters to docker search and docker images |
| Merged | Memory & CPU settings - see: microsoft/opengcs#145 |
| Not started | LCOW: docker run --user seems to be ignored #36469 |
Required for Kubernetes
| Status | Description |
|---|---|
| Not started | Update docker stats for multiple platforms |
| Proposal soon | Update docker info & daemon configuration to show what platforms each node is capable of, and restrict to single platforms if needed |
Required for Swarm
| Status | Description |
|---|---|
| Not started | Add --platform flag support to docker-compose, and docker stack deploy |
| Not started | Update docker stats for multiple platforms |
| Not started | Support multiple platforms for docker volume commands |
| Not started | Adjust Swarm mode placement to handle running multiple platforms instead of just the node's native platform. Until this is done, use docker service create --no-resolve-image as a workaround |
Backlog, need to set priority
| Status | Description |
|---|---|
| Not started | docker top |
| Not started | docker run flags. Feedback welcome on what's needed vs not |
| Not started | docker export, docker import, docker save need platform flags |
| Not started | UID & GID flag support - see: microsoft/opengcs#146 |
| No plans to support | Cross-platform multi stage builds, support for COPY command in Dockerfile |
Glossary & References
- LCOW - Linux Containers on Windows
- GCS - guest compute service. Receives commands from the Hyper-V host services (DockerD via HCS) and invokes processes for specific tasks, creating namespaces, and creating containers using runC. (Repo link coming soon)
- HCS - host compute service. Windows-specific service used to manage containers and VMs (doc link coming soon)
There's a brief description of gcs & hcs from a Dockercon 2016 presentation
FAQs
What's needed to fully test this?
- As of LCOW: (Experimental) Require RS5+ builds #39108, Windows 10 or Windows Server version 1809 (build 17763), or a later Windows Insider build
- A build of moby/moby with the PR's above applied
- A bootable UEFI-based Linux image with the right modules & gcs included - see https://github.com/microsoft/opengcs
- At least 4GB of RAM and Intel VT or AMD-V instruction support
- Note: other apps using these instructions (VMWare, Virtualbox, ...) cannot be run concurrently