Tuesday, October 11, 2016

16.04 - Autostart service

I'm looking for a way to configure a service to run automatically whenever it stops for some reason. Currently I have set up a cronjob that checks if the service is running every minute and restarts it if it has crashed but that seems dull. How can I do this the right way?



I have added some questionable scripts to make the service work, you can see below



x@x:~$ sudo cat /etc/init.d/my-service
#!/bin/sh
### BEGIN INIT INFO

# Provides: my-service
# Required-Start: $remote_fs $syslog
# Required-Stop: $remote_fs $syslog
# Default-Start: 2 3 4 5
# Default-Stop: 0 1 6
# Short-Description: Start daemon at boot time
# Description: Enable service provided by daemon.
### END INIT INFO

dir="/var/www/html/my-service"

cmd="nodejs chat.js"
user="www-data"

name=`basename $0`
pid_file="/var/run/$name.pid"
stdout_log="/var/log/$name.log"
stderr_log="/var/log/$name.err"

get_pid() {
cat "$pid_file"

}

is_running() {
[ -f "$pid_file" ] && ps `get_pid` > /dev/null 2>&1
}

case "$1" in
start)
if is_running; then
echo "Already started"

else
echo "Starting $name"
cd "$dir"
if [ -z "$user" ]; then
sudo $cmd >> "$stdout_log" 2>> "$stderr_log" &
else
sudo -u "$user" $cmd >> "$stdout_log" 2>> "$stderr_log" &
fi
echo $! > "$pid_file"
if ! is_running; then

echo "Unable to start, see $stdout_log and $stderr_log"
exit 1
fi
fi
;;
stop)
if is_running; then
echo -n "Stopping $name.."
kill `get_pid`
for i in {1..10}

do
if ! is_running; then
break
fi

echo -n "."
sleep 1
done
echo


if is_running; then
echo "Not stopped; may still be shutting down or shutdown may have f ailed"
exit 1
else
echo "Stopped"
if [ -f "$pid_file" ]; then
rm "$pid_file"
fi
fi
else

echo "Not running"
fi
;;
restart)
$0 stop
if is_running; then
echo "Unable to stop, will not attempt to start"
exit 1
fi
$0 start

;;
status)
if is_running; then
echo "Running"
else
echo "Stopped"
exit 1
fi
;;
*)

echo "Usage: $0 {start|stop|restart|status}"
exit 1
;;
esac

exit 0


And also my-service.service




x@x:~$ cat /etc/systemd/system/my-service.service
[Unit]
Description=my-service daemon

[Service]
ExecStart=/usr/bin/nodejs /var/www/html/my-service/chat.js
Type=simple
User=root
Group=root
Restart=always


[Install]
WantedBy=multi-user.target


For example when the machine reboots I get this as status



Jan 24 10:54:41 x systemd[1]: my-service.service: Service hold-off time over, scheduling restart.
Jan 24 10:54:41 x systemd[1]: Stopped my-service daemon.
Jan 24 10:54:41 x systemd[1]: my-service.service: Start request repeated too quickly.

Jan 24 10:54:41 x systemd[1]: Failed to start my-service daemon.

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