Better support for portable user service files (rootless).

[gnat]

Is your feature request related to a problem? Please describe.

I'm writing *.service files in ~/.config/systemd/user/ for user level systemd (systemctl --user) service management.

The problem is ExecStart must be an absolute path and cannot use %h. This forces me to have service files that are not portable between users. ExecStart= is pointing to binaries in /home/USER/.local/bin

This path is important as users run more rootless daemons, rootless containers (ex: rootless docker) for security and isolation.

Describe the solution you'd like

• Perhaps add %h/.local/bin to the $PATH when running as --user ?
• Perhaps allow %h in ExecStart=. Example: ExecStart=%h/.local/bin/cockroach ?
• Perhaps an option to automatically add %h to ExecStart= when running as systemctl --user ?

The systemd version you checked that didn't have the feature you are asking for

• systemd 245
• RFE: support specifier expansion for first word of ExecStart= directives #3061 Similar issue previously mentioned here.

Any assistance, suggestions welcome. Thank you!

[mbiebl]

The problem is ExecStart must be an absolute path

This is not true anymore. ExecStart nowadays consults $PATH if a non-absolute path is specified.

[gnat]

This is not true anymore. ExecStart nowadays consults $PATH if a non-absolute path is specified.

Please elaborate or correct me if I'm wrong but I get the following error
May 21 21:25:27 ubuntu systemd[1012]: /home/gnat/.config/systemd/user/cockroach@.service:30: Executable "cockroach" not found in path "/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"

This is after setting Environment=PATH=/home/gnat/bin:/home/gnat/.local/bin:/sbin:/usr/sbin:$PATH in my cockroach@.service file.

The documentation reads:

If the command is not a full (absolute) path, it will be resolved to a full path using a fixed search path determined at compilation time. Searched directories include /usr/local/bin/, /usr/bin/, /bin/ on systems using split /usr/bin/ and /bin/ directories, and their sbin/ counterparts on systems using split bin/ and sbin/.

"determined at compilation time" unfortunately doesn't help in this situation.

[gnat]

Added another solution suggestion of adding %h/.local/bin to the $PATH when running as systemctl --user.

[mbiebl]

You're right, the paths are hard-coded during compilation time. For the user instance, there is the -Duser-path meson option:
https://github.com/systemd/systemd/blob/main/meson_options.txt#L77
https://github.com/systemd/systemd/blob/main/meson.build#L866

I do think that adding ~/.local/bin by default to the user-path would be a good idea.

[poettering]

The problem is ExecStart must be an absolute path and cannot use %h.

It cannot use %h? What makes you think so?

[gnat]

Ended up writing some fresh service files today and to my happy surprise %h and %u are working awesomely in ExecStart=. This must have been a mistake on my end.

Thank you for your patience. Will go ahead and close this.

For the future I do think it would be helpful to add ~/.local/bin to the default PATH when invoking systemctl --user.