Scott Hanselman

Docker Desktop for WSL 2 integrates Windows 10 and Linux even closer

July 30, '19 Comments [13] Posted in Docker | Linux | Open Source
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Being able to seamlessly run Linux on Windows is making a bunch of common development tasks easier. When you're running WSL2 (Windows Subsystem for Linux 2) in a version of Windows 10 greater than build 18945, a BUNCH of useful and interesting scenarios light up and stuff just works.

Docker for Windows (download the Docker Desktop for WSL 2 Tech preview here) is great, but it has historically worked on Windows by creating a Hyper-V virtual machine called Moby that is visible within the Hyper-V client. It's a utility VM, but it's one you're aware of.

Docker for Windows using WSL2

However, if WSL2 runs a real Linux kernel in Windows 10 and it's managing a virtual machine platform underneath (and not visible to) Hyper-V client tools, then why not just let WSL2 handle containers for us?

That's exactly what the Docker Desklop WSL 2 Tech Preview aims to do. And just like WSL 2, it's fast.

...the time required to start a Docker daemon after a cold start is significantly faster. It takes less than 2 seconds to start the Docker daemon when compared to tens of seconds in the current version of Docker Desktop.

Once you've got a Linux (Ubuntu or the like) set up in WSL 2, you can right click on Docker Deskop and click "WSL 2 Tech Preview." This is a goofy and not-super-intuitive UI for now but it's a moment in time.

Click WSL 2 Tech Preview

Then you just hit Start.

NOTE: If you've already installed Docker within WSL 2 at the command line, stop it and let Docker Desktop manage its lifecycle.

Here's the beginnings of their UI.

Docker for WSL2

When I drop out to PowerShell/CMD on Windows I can run "docker context ls."

C:\Users\Scott\Desktop> docker context ls    
NAME DESCRIPTION DOCKER ENDPOINT
default Current DOCKER_HOST based configuration npipe:////./pipe/docker_engine
wsl * Docker daemon hosted in WSL 2 npipe:////./pipe/docker_wsl

You can see there's two contexts, and I've run "docker context use wsl" and that's now my default.

Here is docker images from Ubuntu, and again from Windows (in PowerShell Core). They are the same!

Docker images in Ubuntu
Docker images from Powershell

Sweet. Here I am using PowerShell Core (which is open source and cross-platform, natch) to manage my builds which are themselves cross-platform and I can run both a docker build or a metal build on both Windows or Linux, all seamlessly on the same box.

building docker images

Also note, Simon from Docker points out "We are using a non default dataroot in this mode to avoid corrupting a datastore you use without docker desktop in case something goes wrong. Stopping the docker desktop wsl daemon and restarting the one you installed manually should bring everything back." I noticed this because my "Windows Docker" and my original WSL2 docker had a list of images that I naively expected to be available here, but this is a new context and new dataroot so you may need to fetch images again in this new world if you're have been historically an active docker user.

So far I'm super impressed. Linux on the Windows Desktop feels right. It's Peanut Butter and Chocolate.


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About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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Disclaimer: The opinions expressed herein are my own personal opinions and do not represent my employer's view in any way.