Jtdylktuy

I'm trying to setup a systemd service which executes a script after the system is fully booted (internet access is required) and also executes a different script right before the system shuts down or reboots (internet access is required).

I spend all day yesterday reading dozens of forum posts and guides but can't wrap my head around the logic.
Up until now I got:

[Unit]

Description=Execute custom script on shutdown

After=network.target



[Service]

Type=oneshot

ExecStart=/etc/init.d/hostup

ExecStop=/etc/init.d/hostdown



[Install]

WantedBy=halt.target reboot.target shutdown.target

My thoughts are:
The unit waits on startup for the network.target since it's required to perform the task After=network.target.

On service startup it executes the first script ExecStart=/etc/init.d/hostup.

And finally on shutdown or reboot the second script is executed ExecStop=/etc/init.d/hostdown

Is this even close or do I need to have two seperate services each handling one script?

Also where is the appropriate place to put these scripts. /etc/init.d/ was just an idea.

Any input is appreciated

EDIT:

I invested some more time in it and I now have to separate services:

For startup:

Description=Custom Command on startup

After=network-online.target



[Service]

Type=idle

ExecStart=/etc/init.d/hostup



[Install]

WantedBy=network-online.target

and for shutdown:

[Unit]

Description=Execute custom script on shutdown

Before=shutdown.target network.target



[Service]

ExecStart=/bin/true

ExecStop=/etc/init.d/hostdown

RemainAfterExit=yes



[Install]

WantedBy=halt.target reboot.target shutdown.target

My current problem is defining the runlevels.

when I run sudo systemctl enable hostup.service following error pops up:

Synchronizing state of hostup.service with SysV service script with /lib/systemd/systemd-sysv-install.

Executing: /lib/systemd/systemd-sysv-install enable hostup

update-rc.d: error: hostup Default-Start contains no runlevels, aborting.

Any help on how to define the runlevels correctly would be highly appreciated.

Found a solution that works for me.

Service running on shutdown:

[Unit]

Description=Execute custom script on shutdown

Before=network-online.target



[Service]

ExecStart=/bin/true

ExecStop=/usr/local/bin/hostdown.sh

RemainAfterExit=yes



[Install]

WantedBy=halt.target reboot.target shutdown.target poweroff.target

Service running on startup:

[Unit]

Description=Custom Command on startup

After=network-online.target

After=network.target

After=systemd-user-sessions.service



[Service]

Type=oneshot

RemainAfterExit=yes

ExecStartPre=/bin/sleep 30

ExecStart=/usr/local/bin/hostup.sh

RestartSec=5



[Install]

WantedBy=multi-user.target

The latter may not be the smartest or prettiest solution and I still don't quite understand why it won't work without this line ExecStartPre=/bin/sleep 30

Just thought I'd document my solution for the future.

Comments and suggestions are very much welcome!