Restart loop when using PathExistsGlob

[Antonios Tsianakas]

When using PathExistsGlob in a path unit, systemd starts the corresponding service unit in an infinite loop. We have observed this problem only under Jammy.

--------------
[Unit]
Description=Test

[Path]
PathExistsGlob=/home/www-data/test/*.so
Unit=test.service

[Install]
WantedBy=multi-user.target

--------------
[Unit]
Description=Test

[Service]
Type=simple
ExecStart=echo test
StartLimitBurst=1000

[Install]
WantedBy=multi-user.target

-------------
www-data@josi-test-jammy03:~ $ systemctl --user status test.path
× test.path - Test
     Loaded: loaded (/home/www-data/.config/systemd/user/test.path; disabled; vendor preset: enabled)
     Active: failed (Result: unit-start-limit-hit) since Mon 2022-05-16 17:08:08 CEST; 121ms ago
   Triggers: ● test.service

May 16 17:08:04 josi-test-jammy03 systemd[24979]: Started Test
May 16 17:08:08 josi-test-jammy03 systemd[24979]: test.path: Failed with result 'unit-start-limit-hit'.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Nick Rosbrook (enr0n)]

I think this is to be expected since your service just does one thing and exits immediately -- when the service exists, the PathExistsGlob condition is still true, and so the service is activated again by test.path.

If you had a long running service, or another condition to say "we already ran test.service, no need to run again", you would avoid this.