Am 17.04.2017 um 00:47 schrieb Enrico Weigelt, metux IT consult:
On 17.04.2017 00:04, Lennart Poettering wrote:

Please always check the man pages if you have questions regarding a
specific systemd interface:

https://www.freedesktop.org/software/systemd/man/sd_notify.html

Done so, of course. Unfortunately, it doesn't answer my questions,
eg. what the service manager actually does w/ that information.

really?

what exactly do you not understand in the descriptions below?

if there are several services depending on each other you don't want to start depending services while your big database still inits and is not ready for connections - for "Restart=always" it maybe not enough that your proess is just running - hence the watchdog where the service needs to say "i am still alive"


READY=1

Tells the service manager that service startup is finished. This is only used by systemd if the service definition file has Type=notify set. Since there is little value in signaling non-readiness, the only value services should send is "READY=1" (i.e. "READY=0" is not defined).

Example 2. Extended Start-up Notification

A service could send the following after completing initialization:

sd_notifyf(0, "READY=1\n"
        "STATUS=Processing requests?\n"
        "MAINPID=%lu",
        (unsigned long) getpid());

RELOADING=1

Tells the service manager that the service is reloading its configuration. This is useful to allow the service manager to track the service's internal state, and present it to the user. Note that a service that sends this notification must also send a "READY=1" notification when it completed reloading its configuration.

STOPPING=1

Tells the service manager that the service is beginning its shutdown. This is useful to allow the service manager to track the service's internal state, and present it to the user.

WATCHDOG=1

Tells the service manager to update the watchdog timestamp. This is the keep-alive ping that services need to issue in regular intervals if WatchdogSec= is enabled for it. See systemd.service(5) for information how to enable this functionality and sd_watchdog_enabled(3) for the details of how the service can check whether the watchdog is enabled.

https://www.freedesktop.org/software/systemd/man/sd_watchdog_enabled.html
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