To pile on, a minimal OpenRC service file is just as complicated as a minimal SystemD service file; that is, they're both almost-exclusively composed of key-value pairs. For instance, this is the service file for the 'rsyncd' service [0]:
#!/sbin/openrc-run
command="/usr/bin/rsync"
command_args="--daemon ${RSYNC_OPTS}"
pidfile="/var/run/${SVCNAME}.pid"
depend() {
use net
}
Like SystemD, OpenRC provides pre/post start/stop hooks that you can use to call out to other programs.
Unlike SystemD if you need to make nontrivial decisions at service-status-management time, you have the option of putting your scripts or calls to other programs inline, rather than hoping that SystemD gives you the hooks you need in the places you need them and passes in the data you require. [1]
[0] And if 'rsyncd' was supervised with 'supervise-daemon', you wouldn't need to specify the location of the pidfile.
[1] As a trivial example, you can dynamically depend on other services depending on system configuration (as PostgreSQL does). As a less-trivial example, you can check for and warn the administrator about common service misconfigurations with the same mechanism that provides service startup and status information (as several services do).
Unlike SystemD if you need to make nontrivial decisions at service-status-management time, you have the option of putting your scripts or calls to other programs inline, rather than hoping that SystemD gives you the hooks you need in the places you need them and passes in the data you require. [1]
[0] And if 'rsyncd' was supervised with 'supervise-daemon', you wouldn't need to specify the location of the pidfile.
[1] As a trivial example, you can dynamically depend on other services depending on system configuration (as PostgreSQL does). As a less-trivial example, you can check for and warn the administrator about common service misconfigurations with the same mechanism that provides service startup and status information (as several services do).