[Deployment] Creating ROS 2 Linux services

Creating ROS 2 Linux services

It's a typical requirement that for an embedded system, that it starts the required services and no further action is needed for operation and maintenance. In ROS 1, this task tended to be tedious, many wrapper packages has been developed for automatic start and maintenance.

Fortunately, ROS 2 is specifically designed for production-level embedded systems and blends well with other system-level services and applications.

Creating ROS 2-based system service with systemd

It is possible to create a conventional Linux service for an ROS 2-based application. Just keep in mind: the environment variables and paths must be set explicitly. Also, ROS 2 tasks (run, launch, etc.) can be accessed on a direct path. For example, on my BeagleBone, I start SICK S300 as a systemd service, with the following configuration file (ros2 run is used in this example):

[Unit]
Description=ROS 2 SICK S300 service
 
[Service]
User=debian
Environment="ROS_DOMAIN_ID=0"
Environment="LD_LIBRARY_PATH=/opt/ros/robotom/lib:/opt/ros/foxy/lib"
Environment="PYTHONPATH=/opt/ros/robotom/lib/python3.7/site-packages:/opt/ros/foxy/lib/python3.7/site-packages/"
Environment="AMENT_PREFIX_PATH=/opt/ros/robotom:/opt/ros/foxy"
ExecStart=/opt/ros/foxy/bin/ros2 run sick_s300_ros2 sick_s300_driver_node --ros-args -r /scan:=/robotkocsi0/scan --params-file /opt/ros/robotom/share/sick_s300_driver/configuration/sick_s300.yaml
Restart=on-failure
 
[Install]
WantedBy=multi-user.target
Alias=laserscanner.service

NOTE: always check your system Python version (Python 3.7 or 3.8).

Keep in mind, that these services should be placed in /lib/systemd/system/ folder. From further on, the systemd commands could be used.

As a reminder, to enable a systemd service:

sudo systemctl enable sicks300.service

To start a systemctl service:

sudo systemctl start sicks300.service

To stop a systemctl service:

sudo systemctl stop sicks300.service

To view the status of the SICK s300 service:

sudo systemctl status sicks300.service

To view the journal (the log) of each associated service:

sudo journalctl -u sicks300.service