Running foot server as a service results in incomplete terminal environment

[ibrokemypie]

When starting foot --server as a systemd user service, the resulting foot clients are missing many environment variables which are present in terminals not started as a user service (starting alacritty directly). I believe this is because the session.sh only exports a small number of variables to systemd and dbus, but am not sure the best course of action to resolves this.
#6 related

[alebastr]

I believe this is because the session.sh only exports a small number of variables to systemd and dbus

That is the right assumption. I'm being very careful with the list of copied variables, so it is includes only those that I deemed absolutely necessary. Still less conservative than Arch defaults though.

If you run the shell in footclient, it'll read your shell profile and populate most of the expected environment. The missing vars are something like XDG_SESSION_ID/XDG_VNTR/etc... that supposed to be inherited from the compositor process and aren't used by regular applications.
What are the variables you need for the foot --server itself that are not set by the shell?

On the possible actions:

• Create a file under $XDG_CONFIG_HOME/environment.d/ to define any static variables that you may need for the user service (see environment.d(5) for details).
• Start foot --server directly from sway config, which would inherit env from sway and solve almost all environment issues.
• Import necessary variables yourself with a similar systemd --user import-environment X command in your config
• Convince me that the specific (limited) list of an additional variables would be important for most of the users and should be set by the session.sh script.

[ibrokemypie]

The issue that led me to this was actually the path variable not being set correctly (in foot the path was completely different from the default path set by arch, and I dont think environment.d could solve this (unless it can somehow get the original path variable and then set the new path variable to the old one. I wanted to avoid starting daemons from the sway config because of the note that they wouldnt be picked up by the assign cgroups script, of course its not a huge deal but its less than ideal. Im not sure import-environment x would be ideal either, it would work for the path, but theres various other variables that get set by arch by different packages, such as the CLOUDSDK_* variables.
I'm not actually very clear on the reasoning for only importing specific variables with session.sh so cant really say whether that would be the right place to do it, although I'm fairly certain having the default system set path is probably important for a lot of cases at the very least.
Unless you have a reason not to, I feel like at least PATH should be added to the session.sh imported variables, and then perhaps theres some way to import all variables on a service by service basis? To include all of the original environment for things that need it, like terminal servers.

Obviously I am not very clear on the ins and outs of all of this, so am curious what your thoughts are about the above

[alebastr]

I wanted to avoid starting daemons from the sway config because of the note that they wouldnt be picked up by the assign cgroups script

Good point. It can be worked around with systemd-run --user --scope --unit app-foot\\x2deserver.scope -- foot --server though.

I dont think environment.d could solve this (unless it can somehow get the original path variable and then set the new path variable to the old one.)

There's no original path. systemd user session lives independently from your user session and it never sees your shell environment.
It's getting a bit complicated, but if we somewhat simplify the picture, there will be 3 different sets of environment:

• one is initialized by pam and (e)logind (via pam module) and used to launch the desktop environment once you logged in.
  Sometimes, as a courtesy, display manager imports environment from shell before starting a DE. sddm and greetd do that by default, lightdm can be configured to do so, gdm does not support it.
• one exists within systemd --user and is a rather minimal set of variables defined by environment generators. It's a part of design, as systemd --user can be started before your user logs in and will keep the modified environment once you log out and relogin.
• shell environment, something that is populated when you start bash (zsh, fish, mrsh, etc...) from a number of shell snippets in /etc/profile.d and a few other files. That's the one that will have all these Arch defaults and the PATH value that you expect.
  When you start sway from tty, it obviously inherits everything from the shell and passes that to the other clients.

There is a way to import a PATH value used by the shell with user environment generators though, something like this:

Code

#!/usr/bin/sh
# /etc/systemd/user-environment-generators/99-profile-d-path
# Get PATH from /etc/profile and all /etc/profile.d/* snippets and pass it to the systemd
if [ -f /etc/profile ]; then
    source /etc/profile
    echo PATH=$PATH
fi

And I believe ArchWiki/systemd/User can offer much more on that topic.

I'm not actually very clear on the reasoning for only importing specific variables

1. to be sure that nothing unexpected (LD_LIBRARY_PATH, DBUS_SESSION_BUS_ADDRESS and other vars that can change the behavior of systemd services) slips in.
2. to be able to revert all changes in the environment after logout, so that another DE would not get a stale SWAYIPC or WAYLAND_DISPLAY within systemd user session. You can't do that if you import everything, because you won't know which variable was set by systemd internally and which was imported.

perhaps theres some way to import all variables on a service by service basis

No, I wish there was but alas... There's only Environment= and EnvironmentFile= for static assignments. Although if you can populate EnvironmentFile before starting the service, you can do it that way.

But I'm thinking I need to add --all-environment switch to session.sh that will do exactly that - import all available environment variables. I just can't predict what could be broken by that :-)

Sorry if I skipped any important point, but it's past midnight here so I'll check once again in the morning.

[ibrokemypie]

Thankyou for all of this, it all makes sense. I've started using.config/environment.d which is loaded into zsh shells through .zshenv, which is working well, and also applying to anything started by sway (eg firefox and MOZ_ENABLE_WAYLAND).
I think I'll use your systemd-run snippet specifically for the foot server, just so I dont have to set up generators for each possible environment variable that the shell needs (all the cloudsdk ones for example)
The all-environment argument sounds like a good idea, and with how many people run systemctl --user import-environment in theyre sway configs I guess it wont cause too many problems, but with your suggestions I think this can all work without it.
Thankyou! Closing this issue now as my questions have been answered!

[alebastr]

I added the --all-environment option, but decided to leave it private. The ability to import full environment block is already deprecated in systemd v248+ (systemd/systemd@32854f7) and the reasoning behind that seems sound to me.

I'd actually prefer if another new option for adding an explicitly specified set of variables would be used instead. I.e. session.sh --with-cleanup -E VAR1 -E VAR2 -E VAR3.

[markstos]

Note that soon foot is likely to add systemd socket activation.

https://codeberg.org/dnkl/foot/pulls/890

So, after starting the systemd socket unit for foot, foot --server will be started on demand when the first client tries to connect.

[alebastr]

Yep, I saw #13. Just been busy between work and Fedora things to draft a proper reply.

In regards to the topic of the current issue, I have following (incomplete) solution:

#!/bin/sh
# vim: ts=4 sw=4 noet
# /etc/systemd/user-generators/foot-server-env
#
# Generate environment for the specific user service
# `systemd-generator(7)`

# Generator arguments: normal-dir, early-dir, late-dir
# We need to use the last one for the drop-in files
LATE_DIR="$3"

# Read environment variable from the user's shell
get_user_var () {
        /usr/bin/env -- "$SHELL" -l -c "echo \$$1"
}

generate_path_dropin () {
        DESTDIR="$LATE_DIR/$1.d"
        mkdir -p "$DESTDIR"
        cat >"$DESTDIR/environment.conf" <<-EOF
        # Automatically generated by $0 at $(date --utc)
        [Service]
        Environment=PATH=$(get_user_var PATH)
        EOF
}

generate_path_dropin foot-server.service

I believe my debugging has stopped on an attempt to figure out why this script completely ignores ~/.zprofile 😄