Set $NOTIFY_SOCKET for ExecStop= processes, and process notify messages from them

[joukewitteveen]

Submission type

• Bug report
• Request for enhancement (RFE)

NOTE: Do not submit anything other than bug reports or RFEs via the issue tracker!

systemd version the issue has been seen with

231

NOTE: Do not submit bug reports about anything but the two most recently released systemd versions upstream!

Used distribution

Arch Linux

In case of bug report: Expected behaviour you didn't see

Updating the unit status string through systemd-notify --pid --status="this service is no longer running so the old status should be invalidated" should update the unit status string.

In case of bug report: Unexpected behaviour you saw

No update could be performed as $NOTIFY_SOCKET was not set for the 'ExecStop' process. This happens when the service type is 'notify' and 'NotifyAccess' is not set (implicitly set to 'main'). I feel that the ExecStop process should behave as the main process.

In case of bug report: Steps to reproduce the problem

Try to update the process status from a program run via 'ExecStop'.

[joukewitteveen]

I think the offending piece of code is the presence of EXEC_IS_CONTROL in src/core/service.c:service_enter_stop. Is it very unreasonable to expect the ExecStop process to behave as the main process?

[davidstrauss]

I'm not sure I understand the use case. An ExecStop= should perform actions to shut down the daemon, which should cause the daemon tell the notify socket that it's stopping.

[joukewitteveen]

For a RemainAfterExit= daemon, all stopping functionality takes place in the ExecStop= process. Consider the following:

[Service]
Type=notify
RemainAfterExit=yes
ExecStart=systemd-notify --pid --status="Going strong" --ready
ExecStop=systemd-notify --pid --status=""

This does not work as desired because the ExecStop= process is not allowed to notify. Of course, this can be solved by opening up NotifyAccess=, but this feels like overkill. Maybe make ExecStop= the main process if the ExecStart= process has already exited? Or include more granularity (NotifyAccess=toplevel for access only to processes started by systemd itself)?

[poettering]

Hmm, I figure we could also set the env var for ExecStop=, at least depending on some setting in NotifyAccess= as proposed.

[evverx]

Closed by #4745