DIND image for Windows

[donny-dont]

Are there any plans for a DIND image for Windows? I'm looking to add support in Drone to build docker windows images but I don't currently see a DIND I can base the image on.

[yosifkit]

That would require some sort of support from Windows and is not something that they are working on. What is the goal? To just have separate storage of image layers like the Linux DIND? Maybe with enough users wanting this, it might be better filed in docker/docker to try and get support from the Windows guys.

For Linux docker-in-docker you are still running containers at the host level, just controlled by a docker daemon within a container (running --privilged so it has unfettered access to the host system) and a different storage directory.

[donny-dont]

@yosifkit the goal in this case would be to be able to build Windows containers within a CI system that runs its builds within containers.

Drone is currently doing what you are describing in linux where the container is given privileged access so it can control a build within the container.

I wasn't sure if this was something possible in Docker for Windows and if there was any plans to formalize it into a dind image on Windows.

[tianon]

I asked some Windows folks about the possibility a while back and the answer was that it's not on the roadmap. 😔

[tianon]

Closing, given that this requires support both from the Windows Kernel/HCS folks and Docker (and there's nothing we can do in this image). Maybe this will be possible someday! 😇

[jankap]

There are images for windows servercore: https://hub.docker.com/_/docker/ and https://github.com/docker-library/docker/blob/83e4de3bc2aac346e2f76129b1a3a556c1e1bb95/20.10/windows/windowsservercore-1809/Dockerfile

however, I can't get them running since --privileged is not supported on Windows. I guess that docker cannot start in the guest:

So why do these images exist?

[yosifkit]

So why do these images exist?

The windows images are for having a client-side docker, not for running "docker-in-docker" (dind).

[jankap]

So why do these images exist?

The windows images are for having a client-side docker, not for running "docker-in-docker" (dind).

Thanks. I could passthrough the host Docker Service via named pipes, so this feels like a Docker in Docker lite, because I can still build images from inside this image. I wonder why this is almost not documented, are there drawbacks using that mechanism?

I wonder how to build Docker Windows images from GitLab CI pipeline without Docker in Docker?

[tianon]

To build Windows Docker images, you'll have to have a Windows Docker engine running somewhere and the ability to connect to it. Doing so in GitLab CI is probably going to require a Windows worker and mounting the named pipe inside your jobs somehow (I'd suggest asking in a GitLab specific forum for more assistance doing so).

[fstamour]

Locally, I was able to run docker-in-docker on windows, with windows container with this:

docker run -it --rm --volume //./pipe/docker_engine://./pipe/docker_engine docker:20.10-windowsservercore-1809

[tianon]

That's not the Docker engine running in Docker, but rather the Docker client running inside Docker, talking to the Docker engine on the host (which isn't really docker-in-docker in the same way running docker:dind is).

[vancouverwill]

why is this not mentioned in either the Dockerfile https://github.com/docker-library/docker/blob/ca257b920303ae46cff2a8399471318ad48d67b4/20.10/windows/windowsservercore-ltsc2022/Dockerfile or https://hub.docker.com/_/docker where it specifically talks about Docker in Docker?

[tianon]

Good point! Opened docker-library/docs#2157 👍

[vancouverwill]

thanks @tianon

[psimms-r7]

With k8s dockershim deprecation is there plans for support of a dind image for windows?

[tianon]

Sorry, I'm really confused - I understand each half of that, but not what they have to do with each other? 😅

Are you perhaps looking for https://github.com/Mirantis/cri-dockerd (which is the new externally-maintained "dockershim" replacement if you want Docker underneath Kubernetes)?

[mayur7436]

To build Windows Docker images, you'll have to have a Windows Docker engine running somewhere and the ability to connect to it. Doing so in GitLab CI is probably going to require a Windows worker and mounting the named pipe inside your jobs somehow (I'd suggest asking in a GitLab specific forum for more assistance doing so).

@jankap Did you manage to build images from inside this image? And how did you passthrough the host Docker Service via named pipes as you mentioned to be able to build images from inside this image?