On Thu, 19 May 2016, Bao Nguyen wrote:
Hi everyone,
When the system is shutdown, systemd will terminate all services in
parallel manner, could you let me know if there is any ways to tell systemd
to shutdown a specific service first, then shutdown all remaining services?
Hello,
I haven't tested it, but as far as I know all you need to do is ensure
your special service is After=multi-user.target, i.e.:
[Unit]
Description=Some service that must be started late / stopped early
After=multi-user.target
[Service]
# ...
[Install]
WantedBy=multi-user.target
A target unit is automatically After= all the units that it Wants=,
Requires=, etc., but this automatic dependency is *not* added if that
would create a dependency loop.
So at shutdown systemd knows it needs to stop all services and targets.
Because your special service is After=multi-user.target, and
multi-user.target is After= all *other* normal services, everything gets
ordered correctly: your service is stopped first, then multi-user.target
is stopped, then all the other services are stopped.
Now, this isn't the *cleanest* solution -- you really want to be specific
in your service dependencies rather than depending upon a whole target's
worth of services, and there's always the chance that multi-user.target
might be stopped some other way before shutdown -- but it does seem as if
it goes some way to solving your problem.
- Michael
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