Ttgjyuk

I am trying to run a Mosquitto MQTT Broker on Ubuntu 16.04. I have instructions from 14.04, but since 16.04 no longer uses startup, I can't figure out how to convert to systemd.

Here are the commands for 14.04:

description "Mosquitto MQTT broker"
start on net-device-up
respawn
exec /usr/sbin/mosquitto -c /etc/mosquitto/mosquitto.conf

EDIT:

This is what I got to so far. When I reboot and run systemctl status mosquitto.service I show that mosquitto is loaded but not active:

[Unit]
Description=Mosquitto MQTT Broker

[Service]
WorkingDirectory=/usr/sbin/mosquitto
ExecStart=/etc/mosquitto/mosquitto.conf
Restart=always

[Install]
WantedBy=multi-user.target

EDIT 2:

Ran sudo systemctl enable mosquitto.service. Now the error exit code is:

Process: 1720 ExecStart=/etc/mosquitto/mosquitto.conf (code=exited, status=200/CHDIR)

Installing sudo apt install mosquitto on 16.04 adds the /etc/init.d/mosquitto script. systemd uses that script to generate /run/systemd/generator.late/mosquitto.service, and this is what it says:

# Automatically generated by systemd-sysv-generator

[Unit]
Documentation=man:systemd-sysv-generator(8)
SourcePath=/etc/init.d/mosquitto
Description=LSB: mosquitto MQTT v3.1 message broker
Before=multi-user.target
Before=multi-user.target
Before=multi-user.target
Before=graphical.target
Before=shutdown.target
After=remote-fs.target
After=systemd-journald-dev-log.socket
Conflicts=shutdown.target

[Service]
Type=forking
Restart=no
TimeoutSec=5min
IgnoreSIGPIPE=no
KillMode=process
GuessMainPID=no
RemainAfterExit=yes
ExecStart=/etc/init.d/mosquitto start
ExecStop=/etc/init.d/mosquitto stop
ExecReload=/etc/init.d/mosquitto reload

Looking inside /etc/init.d/mosquitto tells us that

/usr/sbin/mosquitto -c /etc/mosquitto/mosquitto.conf is already run by default

So just put your config into /etc/mosquitto/conf.d (referenced by mosquitto.conf) and enjoy.

Being a regular systemd service, you can:

• 
  systemctl status mosquitto to see its current status


• 
  sudo systemctl (start|stop) mosquitto to change the status for the current session


• 
  sudo systemctl (enable|disable) mosquitto to change startup behavior (without affecting the current state)

Your unit file's ExecStart= and WorkingDirectory= lines are completely wrong. Are you trying to start a config file, using the executable file(!) as its working directory?

If I understand correctly, the proper unit file would be:

[Unit]
Description=Mosquitto MQTT Broker
After=network.target

[Service]
ExecStart=/usr/sbin/mosquitto -c /etc/mosquitto/mosquitto.conf
Restart=always

[Install]
WantedBy=multi-user.target

Also, please don't conflate starting and enabling the unit. Read my similar answers about this:

• start nginx on boot


• Is it expected for systemd to start disabled services?

Be sure that you have mosquitto running:

ps -aux | grep mosquitto

And you have this in default.conf:

listener 1883