My Journey From Early Linux, Through Snap Packaging, to WSL

My journey from early
Linux, through Snap
packaging, to WSL
Dani Llewellyn (diddledani) she/her

09/11/2022 Dani Llewellyn 2
My Background
●
Linux user since ~1997-8
●
Web, Desktop, and Server dev/admin experience
●
Windows, macOS, and Linux
●
Single System Image Beowulf-style clustering ~2001-5 (OpenMosix)
●
Ran Gentoo for a decade learning a LOT
●
Learned high-availability techniques via tools like CoroSync and Pacemaker
●
Have since forgotten it all 😛
●
Used Docker and containerisation since Docker first appeared
●
Primary contributions to Snaps/Snapcraft, WSL2, and Ubuntu Mate
●
Featured multiple times on the Ubuntu.com Blog
●
Ubuntu Member February 2018
●
Ubuntu Membership Board September 2018-present
●
Microsoft MVP primarily for WSL-related community work

First contributions

Discovering Snapcraft
●
Followed the Ubuntu Phone
project avidly
●
Inspired by the Click
Packaging system
●
Ubuntu Phone ceased
development
●
Snap Packaging arose from
the ashes

Heavily invested in Snaps
●
My involvement in Snap Packages and Snap ecosystem
snowballed
●
Became the go-to expert on Snap Packaging
●
Regularly consulted by Canonical employees
●
Attendee of multiple Snapcraft Summits
●
Invented multiple techniques for improving and simplifying
Snap Packages
●
Fully committed to their future

In the beginning, there was WSL
●
An emulation layer, often compared to WINE
●
Uses “picoprocesses”
●
Filesystem handled via NTFS
●
The root filesystem tree is stored as native NTFS file entries
●
Each file in the distro is a separate file in NTFS
●
Some changes were made to NTFS to enable Linux file semantics to be stored
appropriately
●
Interop is possible
●
Access Windows files from Linux programs
●
Execute Windows programs from the WSL terminal
●
Use Windows programs to open files inside the WSL distro

Then they said “let there be version 2”,
and there was version 2, and it was good
●
"Lightweight" Virtual Machine
●
Uses Hyper-v via the Host Compute Service
●
Doesn’t need the full Hyper-v management stack
●
Each distro is inside its own set of namespaces on a shared kernel
●
Filesystem handled via Virtual Disk Image
●
Uses real kernel from kernel.org with some MS patches
●
Patches primarily to enable better interoperation with Windows such as the DirectX driver for GPU
compute and 3D acceleration support (WSLg)
●
Runs at almost native speed
●
WSLg (Windows 11 only) allows graphical apps without running an X11 service on your
Windows desktop
●
Using real Linux means Systemd is possible and with it Snap Packages

Wait, no Snap support?

My work with WSL2: Systemd
●
Developed a technique to get Systemd running
●
Codified in https://github.com/diddlesnaps/One-Script-WSL2-Systemd
●
Used a nested process namespace
●
Required lots of hoop-jumping
●
Some issues with interaction
●
Getting VSCode Remote to reliably enter the namespace was difficult and regularly broke
●
Microsoft has now released Systemd support natively in Windows 11 as of 21st
September 2022 (via the Windows Store edition of WSL2)
●
This was heavily influenced by my proof, and those of alternative implementations like Genie,
that it is viable and in-demand
●
Canonical were ready to go their own way for Ubuntu, i.e. my way, if MS didn’t provide it natively
– they had an implementation ready to go long before MS announced native support publicly

My work with WSL2: Snaps
●
My main focus for WSL2 was to get Snaps running after
Systemd was functional
●
Mostly it just worked once Systemd was running
●
Snaps ideally need Apparmor in the kernel for “Strict Confinement”
support
●
Microsoft’s provided kernel does not enable Apparmor as provided
●
To enable Apparmor a kernel rebuild is required
●
I have automated this rebuild at
https://github.com/diddlesnaps/WSL2-Linux-Kernel

My work with WSL2: Hayden Barnes
●
Invited by Hayden to present my work on Snaps on WSL2 at the Mini WSLConf
●
Hayden consulted my expertise for input while writing his book: “Pro
Windows Subsystem for Linux (WSL): Powerful Tools and Practices for Cross-
Platform Development and Collaboration” published by Apress
●
I provided insights about interop such as how to use Outlook from WSL2 to send
emails by replacing the sendmail command
●
Investigated and documented managing WSL2 instances with:
●
Canonical’s Landscape
●
Microsoft’s InTune
●
Ansible
●
More besides...

Current and Future Plans
●
Graphical Snap Applications via WSLg with 3D acceleration support
●
Needs more support from Snapd – I have an initial PR
●
I need to actually test it, re-roll, and improve it – Limited by inability to build the snapd snap until
I got my OCI container supporting core builds again recently
●
I want to ensure strict confinement works when WSL2 has AppArmor available
●
Automated Testing of WSL & WSL2 projects
●
Spinning up a matrix of Windows releases
●
Testing my project(s) against this matrix
●
Disposing of the test machines again
●
My VMs are currently broken when hosting Windows 11 22H2 though - investigating
●
Super Secret future project that I’m researching now

Wait, Secret Project?

The inspiration
●
Hayden Barnes posted this video to Twitter last year showing
XFCE on Windows login

Investigations
●
I’ve been intensely investigating logind and user sessions
●
Thinking about the WSLg setup using a separate system container to host Wayland and
Weston
●
Maybe we can port the Weston changes to Mutter and other Wayland compositors to
support their use on WSLg by their various desktop environments
●
We need to know the WSL2 Hyper-V VM identity for Hyper-V Socket establishment by
Remote Desktop Connection client
●
This ID is currently exposed to the Weston in the system container by an environment variable set up
by the Microsoft init process, but we might be able to discover this in the distro container?
●
HCS does not expose this metadata easily for query via scripted calls into Windows from WSL2
●
We also need to be able to tell Remote Desktop Connection that desktop windows should
be bottom-most in the stack and never overlay Windows app windows or other WSL app
windows

The Plan...
●
If this is indeed possible in the long run I plan:
●
Automatic start of Linux desktop environment using WSLg-style
GUI passthrough to Windows
●
Windows’ explorer.exe automatic launch on login will be replaced
by an automatic launch of our Linux desktop environment instead
●
Windows apps will have shortcuts forwarded to the Linux Desktop
Environment’s menu
●
This is the reverse to what WSLg currently does in putting the Linux apps
in the Windows start menu

Why?
●
Will be mind-blowing if I get it going
●
Needs a lot of development time, and even more research
●
Will truly make the “Year of the Linux Desktop” naysayers sit
up and take notice, if it can be done
●
Even if they just ridicule it

404: Demo not found
●
I hoped to have a very rough Proof of Concept but I didn’t
have time to get it going… also I left it far to late to even start
preparing it 🤦‍♀️

Acknowledgements
●
Hayden Barnes (formally of Pengwin, also formally WSL lead at Canonical;
@unixterminal) and Nuno do Carmo (of Rancher Labs at SuSE; @nunixtech)
●
For helping me with WSL2 experiments and sharing their knowledge freely
●
Heather Ellsworth (Ubuntu Desktop team; @linux_flower) and Monica Madon
(former Ubuntu Community Respresentative; @communiteatime)
●
For being excellent friends and providing constant encouragement and moral support,
especially while I'm trying to find work that is suitable for my talents
●
Martin Wimpress (@m_wimpress), Alan Pope (@popey) both alumni of
the Snap Advocacy team
●
For recognising my capability and enthusiasm for the Snap Packaging world, inviting me
to Snapcraft Summits to share my knowledge, and encouraging me to get deeper into the
Ubuntu Community

Where to find me
●
WSL Chat on Telegram (set up by Hayden Barnes):
https://t.co/TNYoOqS5P7
●
Ubuntu Discourse (diddledani)
●
Snapcraft Forum (diddledani)
●
https://github.com/diddlesnaps
●
https://github.com/diddledani
●
https://github.com/UbuntuAccomplishments
●
Twitter (@diddledani)
●
Mastodon (@diddledani@mastodon.lol)
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Also: I’m currently looking for work 😉

My Journey From Early Linux, Through Snap Packaging, to WSL

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