dbbao / bottle-imp

A spinoff of genie to supplement WSL's new built-in systemd support.

bottle-imp

A helper for using WSL's native systemd support

bottle-imp is a spinoff of systemd-genie to supplement WSL's new built-in systemd support.

Why is this necessary?

Well, awesome as the native systemd support is, there are some things it doesn't do, and others that it does in notably different ways from genie or other existing systemd solutions. For more information, you can see my migrating from systemd-genie to native WSL systemd article here.

What does it do, exactly?

The following features are provided by bottle-imp (see the above article for more in-depth explanations):

• Ensures that securityfs (needed for AppArmor and LSMs) and pstorefs (for debugging panics) are mounted.
• Ensures that the symlink of /tmp/.X11-unix/X0, which makes WSLg work, is restored after systemd clears out /tmp.
• Ensures that WSL interop is working, even after systemd rebuilds the binfmts.
• Makes sure systemd is up and running before proceeding.
• Mounts the WSLg-created user runtime directory over the systemd user runtime directory, ensuring everything's in the right place.
• Keeps the WSL instance running even when you have no active sessions.

and the big one

• Creates a login session for you, along with a user systemd and a session dbus.

REQUIREMENTS

First, obviously, if you were previously a user of systemd-genie or one of the other systemd solutions, uninstall it before attempting to set up native systemd support or bottle-imp.

It is a good idea to set your systemd default target to multi-user.target before enabling systemd native support. TThe default graphical.target used by many distributions includes services for the graphical desktop that would take, at minimum, considerable reconfiguration before operating properly under the WSL/WSLg environment.

If you are using a custom kernel for WSL, it should comply with the suggested means of detecting WSL given in microsoft/WSL#423 (comment) - i.e., the string "microsoft" should be present in the kernel version string, which can be found in /proc/sys/kernel/osrelease. You can check this by running systemd-detect-virt; it should return "wsl".

Obviously, since native systemd support only works under WSL 2, the same can be said for imp.

Some systemd units were problematic for various reasons under genie, and continue to be so under native support. A list of common problematic units and solutions is available here.

INSTALLATION

If there is a package available for your distribution, this is the recommended method of installing genie.

Debian

Dependent packages on Debian are libc6 (>= 2.34), python3 (>= 3.7), python3-pip, python3-psutil, systemd (>= 232-25), and systemd-container (>= 232-25). These should all be in the distro and able to be installed automatically.

To install, add the wsl-translinux repository here by following the instructions here:

https://arkane-systems.github.io/wsl-transdebian/

then install imp using the commands:

sudo apt update
sudo apt install -y imp

Arch

An Arch package (.zst) for amd64 can be downloaded from the releases, to right. Install it manually, using pacman -U <file>.

Other Distros

If your distribution supports any of the package formats available, you may wish to try downloading the relevant format and giving it a try. This will almost certainly need some tweaking to work properly.

Debian is the "native" distribution for bottle-imp, for which read, "what the author uses". Specifically, Debian bullseye+, with usrmerge installed.

TAR

There is a .tar.gz of a complete genie install available from the releases, to right. As a last resort, you can try untarring this (it contains every needed file, with the correct permissions, in the correct path from /) onto your system while root. Don't do this unless you're confident you know what you're doing, you're willing to go looking for any resulting issues yourself, and you aren't afraid of accidentally breaking things. You will need to install the dependencies listed above beforehand.

USAGE

usage: imp [-h] [-V] [-v] [-a USER] (-i | -s | -l | -c ...)

Helper for using WSL systemd native support.

options:
  -h, --help            show this help message and exit
  -V, --version         show program's version number and exit
  -v, --verbose         display verbose progress messages
  -a USER, --as-user USER
                        specify user to run shell or command as (use with -s or -c)

commands:
  -i, --initialize      initialize WSL interop for user sessions and hold WSL open until explicit shutdown
  -s, --shell           open or connect to a systemd user session, and run a shell in it
  -l, --login           open a login prompt for a systemd user session
  -c ..., --command ...
                        open or connect to a systemd user session, and run the specified command in it (preserves working directory)

For more information, see https://github.com/arkane-systems/bottle-imp/

There are four primary commands available in bottle-imp.

imp -i should be run first to set up your WSL instance. It has two effects (apart from waiting for systemd to be ready); it copies the necessary information to ensure that Windows interoperability works inside systemd-managed login sessions and even services, and it starts a lifetime-running process to ensure that the WSL instance does not terminate even when you have no interactive sessions open.

NOTE: For technical reasons, it is not currently possible to separate these functions; you can't have reliable Windows interop without the lifetime-running process.

NOTE 2: The below commands will still work even if you do not run imp -i; however, Windows interop will not function inside systemd-managed sessions, and the WSL instance will idle-terminate as soon as there are no interactive sessions (technically defined as processes that are children of the Microsoft init) running.

imp -s runs your login shell inside a systemd login session; basically, Windows-side, wsl imp -s is your substitute for just wsl to get started, or for the shortcut you get to start a shell in the distro. It follows login semantics, and as such does not preserve the current working directory.

imp -c [command] runs command inside a systemd login session, then exits. It follows sudo semantics, and so does preserve the cwd.

With either of the above, the imp -a [user] option may be used to specify a particular user to start a shell for, or to run a command as, rather than using the currently logged-in user. For example, imp -a bongo -s would start a shell as the user bongo.

imp -l opens a login prompt. This permits you to log in to the WSL distribution via systemd as any user. The login prompt will return when you log out; to terminate the session, press ^] three times within one second. It follows login semantics, and as such does not preserve the current working directory.