Services

Author

Affiliation

Paolo Bosetti

University of Trento

Abstract

Once tested, agents can be turned into linux services, so that they start automatically on boot.

Why services

Agents are typically expected to run on boot: as soon as the machine or device starts, you want the agent to become immediately available. To do that, MADS offers a solution for quickly create a service for a given combination of MADS command and arguments.

Warning

At the moment, this functionality is only available on Linux (Ubuntu or Debian). There are no immediate plans to extend it to MacOS or Windows.

What is a service

On Ubuntu or Debian Linux, a service is a INI file located in /etc/systemd/system that details a command to be executed on boot and its requirements. Once you have the service file installed, e.g. as /etc/systemd/system/my_service.service, you can:

• Enable/disable the service: sudo systemctl enable|disable my_service. If the service is disabled, It does not starts automatically.
• Start the service manually: sudo systemctl start my_service
• Stop the service manually: sudo systemctl stop my_service
• Enquire the service status: sudo systemctl status my_service

So, if the service is enabled, it starts automatically on boot; if it is disabled, you can still start it with the systemctl start command.

How to create a MADS service

Suppose that you know that the following command launches properly an agent:

mads source -i in0_01 arduino.plugin

Now you want turn this command into a service. Just put mads service <service_name> in front of that command line, e.g.:

mads service arduino source -i in0_01 arduino.plugin

where mads service arduino means “create a service file called mads-arduino” (mads- is added automatically), and source -i in0_01 arduino.plugin is the proper command line for the mads command.

You should get an output like:

#  __  __    _    ____  ____
# |  \/  |  / \  |  _ \/ ___|
# | |\/| | / _ \ | | | \___ \
# | |  | |/ ___ \| |_| |___) |
# |_|  |_/_/   \_\____/|____/
#
# Linux Systemd service file for mads-arduino, a mads-source agent
# Notice that the settings file will be read from
# /usr/local/etc/mads.ini
#
# Save this file to /etc/systemd/system/mads-arduino.service
# Or run "sudo mads service publish source publish.plugin "
# then run "sudo systemctl enable mads-arduino.service"

[Unit]
Description=mads-arduino
After=network.target
StartLimitIntervalSec=0

[Service]
Type=simple
Restart=always
RestartSec=1
User=root
ExecStart=/usr/local/bin/mads-source -i in0_01 arduino.plugin

[Install]
WantedBy=multi-user.target

As instructed in the comments, you shall check if everything looks fine, and if so, install the service file in the proper directory by simply re-executing the same command with sudo :

sudo mads service arduino source -i in0_01 arduino.plugin

A longer and more flexible path is to save the file locally, edit it to taste, then manually copy/move it to /etc/systemd/system:

mads service arduino source -i in0_01 arduino.plugin > mads-arduino.service
# edit the file to taste
sudo cp mads-arduino.service /usr/systemd/system/

Tip

The fist way is the suggested one, unless you really need to adjust the service file (and you know what you are doing).

Finally, enable the service with sudo systemctl enable mads-arduino.service.

Note that enabling the service does not makes it start: to do so, you either have to reboot the machine or to manually start with sudo systemctl start mads-arduino.service.

Special case: broker service

The broker launched as mads broker interacts with the console, waiting for keystrokes. This is not ideal for a service, and would increase the CPU load unnecessarily.

To avoid this problem, the broker shall be called with the -d (daemon) option:

sudo mads service broker broker -d