Docker Desktop 2 Unix Socket Not Available on Alpine WSL 2

Callback Insanity
4 min readFeb 4, 2020

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Meanwhile, in our Ubuntu distribution:

ps aux | grep docker-desktop-proxy

And in Alpine?

Troubleshooting issue: https://github.com/docker/for-win/issues/5096#issuecomment-572730439

Given the lack of information about how the WSL image is built and bootstrapped, some light reverse engineering is in order:

sudo find / -name docker-desktop
..
./wsl/docker-desktop
./var/lib/docker-desktop

What’s in /wsl :

What’s in /wsl/docker-desktop :

On Alpine WSL, /var/run is devoid of any life forms:

However, there is a /wsl/docker-desktop/docker-desktop-proxy file:

But it seems like something’s amok with it’s execution. It is a binary file, so there’s no way to inspect it’s content’s from the shell.

To wit, bind mounts are working inside Alpine. It’s just the Docker socket that is not.

And I don’t know how to manually execute the proxy to see if there’s any error output.

More research: https://www.digitalocean.com/community/questions/how-to-fix-docker-got-permission-denied-while-trying-to-connect-to-the-docker-daemon-socket

Not directly related to WSL, obviously, but…

Ubuntu has docker group out of the box …
Alpine has a docker group as well

What were again the perms on Ubuntu WSL’s socket?

The TCP option.

Trying to use Docker Desktop’s port 2375 as a fallback.

Is the Docker Engine TCP port 2375 even open?

Looks like so.

What about IP address?

Looks like host.docker.internal is still available on DD 2.2:

It belongs to Windows Wi-Fi adapter:

ipconfig on Windows

Can be pinged directly using 192.168.1.235 from Ubuntu WSL, but not via hostname host.docker.internal:

Reachable from Alpine too:

It is also responsive via telnet on Alpine. Previously tyring using localhost or 127.0.0.1 would not work (like it used to on WSL version 1):

I think I might have a winner here, then.

Change Alpine’s ~/.bashrc from:

to:

export DOCKER_HOST=tcp://192.168.1.235:2375

Hmm. It just blanks out.

It seems WSL also throws in it’s own network stack:

The WSL address is pingable from both Ubuntu and Alpine WSLs:

But will it work.

Nope. It hangs as well.

And after a day and a half of trying to use Alpine to connect to Docker Desktop, I have to throw in the towel and temporarily switch to Ubuntu WSL full-time.

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Callback Insanity
Callback Insanity

Written by Callback Insanity

Organic, fair-sourced DevOps and Full-Stack things. This is a BYOB Establishment — Bring Your Own hipster Beard.

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