FSAE ROS2 Workshop

This repo is a fun and interactive learning resource made to teach others about ROS2. This is not a fully comprehensive guide, and it is recommended the workshop host already knows enough ROS2 in order to run it. Included is a set of activities that a host can run with a group of people with readmes and templated source code.

The accompanying slides can be found on our sharepoint drive here.

This repo is further comprised of the /UOA-FSAE/FSAE-ROS2-Workshop-Workspace repo, within which the activity instructions and templates are found.

Included are utility scripts and dockerfiles for setting up docker containers for attendees to access through ssh.

Workshop Instructions

Setup (before workshop)

1. Sort out a networking solution

   • If multiple machines are being used as host ensure they are on the same local network.
   • All Attendees should connect to the same network.
   • In particular ensure they are on the same VLAN (networks with the same SSID) and same subnet. Ie the network name (UoA-WiFi) and host address (the part masked by the Subnet Mask) are the same. This can be checked using ipconfig on windows or ifconfig on linux. Eg. with a Subnet Mask of 255.255.254.0 the address 172.23.40.189 is on the 172.23.40.0 subnet.
   • It is highly unlikely everyone will be allocated to the same subnet via a university router.
   • For more control, set up a local network using a FSAE router to have everyone (including the host devices) communicate over.

2. This repo should be cloned onto the device(s) which will host the docker workspaces.

   • mkdir workshop
   • cd workshop
   • git clone https://github.com/UOA-FSAE/FSAE-ROS2-Workshop

3. Set container ssh password environment variables

   • Define the password used to access the containers over ssh using export WS_PSWD=<write_password> in Linux or set WS_PSWD=<write_password>
   • To view this password against use echo $WS_PSWD in linux or echo %WS_PSWD% in windows.
   • (Optional) Define the password used to access the host container(s) over ssh using export HOST_PSWD=<write_password> in Linux or set HOST_PSWD=<write_password>
   • (Optional) To view this password against use echo $WS_PSWD in linux or echo %WS_PSWD% in windows.

4. Build the docker images

   • Run docker build --build-arg WS_PSWD=fsaedevs --build-arg ROS_DOMAIN_ID=24 -t devs_ws:copy_fs -f docker/ws.DockerFile .
   • Run docker build --build-arg WS_PSWD=fsaehost47 --build-arg ROS_DOMAIN_ID=24 -t devs_ws:host -f docker/ws_host.DockerFile .

5. Build packages

   • colcon build --symlink-install --packages-select turtle_tron turtle_tron_interfaces --cmake-args -DPYTHON_EXECUTABLE=/usr/bin/python3.8

6. Set up the docker environments (on each host machine) by running ./start_container.bash <NUMBER_OF_CONTAINERS>.

   • Each container has port forwarded to it's ssh service begining from 60000.
   • The ssh password to each container is WS_PSWD set previously.
   • The root user is fine for attendees to use. This gives them sudo-privileges.

7. Distribute the host machine's IP(s) and forwarded ssh ports to each attendee.

   • ssh commands are as followed ssh root@<host_ip> -p <ssh_port>
   • distribute the password

8. open 2 docker exec instances

9. launch the turtlesim node

   • run ros2 run turtlesim turtlesim_node --ros-args -p background_r:=255 -p background_g:=255 -p background_b:=255

10. launch rqt introspection plugin

Demonstration (during workshop)

Spawn a turtle from off-screan ros2 service call /spawn turtlesim/srv/Spawn "{x: 2, y: 2, theta: 0.2, name: '$TURTLE_NAME'}"

1. start Tron
2. start a new sim ros2 run turtlesim turtlesim_node --ros-args -r __node:=turtlesim_tron -pbackground_r:=255 -p background_g:=255 -p background_b:=255 run tron node ros2 run turtle_tron tron_game set team colors ros2 service call /tron_game/set_team_color turtle_tron_interfaces/srv/SetTeamColor "{team: 0, r: 255, g: 0, b: 0, width: 10}" ros2 service call /tron_game/set_team_color turtle_tron_interfaces/srv/SetTeamColor "{team: 1, r: 0, g: 255, b: 0, width: 10}"

assign teams ros2 service call /tron_game/assign_teams std_srvs/srv/Empty

start game ros2 service call /tron_game/start std_srvs/srv/Empty ros2 service call /tron_game/start std_srvs/srv/Empty

respawn players ros2 service call /tron_game/respawn_all std_srvs/srv/Empty

when ws containers are stopped the container is not removed in case a user wants to reconnect and resume.

The host container is automatically removed when stopped.

If the readmes are updated, they can be re-exported using the VS Code Markdown PDF extension

If you get the following error you can resolve it by running ssh-keygen -R <HOST-IP>:<PORT>

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@    WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!     @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that a host key has just been changed.
The fingerprint for the ED25519 key sent by the remote host is
SHA256:lf5fZ9te8RkNRDkVZJMN0ubXc3+CxitpHzI3bdwHWlM.
Please contact your system administrator.