Understanding ROS2 components

Understanding colcon

Colcon stands for collective construction. It automates the process of building, testing and using multiple software packages. ¹

Use of --symlink-install in colcon build ²

• On enforcing --symlink-install, any changes in python source code will take effect without re-building (not applicable to C++)

Difference between local_setup.zsh and setup.zsh ³

• If you want to source the first workspace (e.g. /opt/ros/foxy) it doesn’t make any difference because that workspace doesn’t have any parent workspaces
• If you have built your own workspace ~/ws after sourcing /opt/ros/foxy you can do either of the following:
  • Source ~/ws/install/setup.zsh to setup the environment to include paths from /opt/ros/foxy as well as ~/ws/install
  • That is the same as if you would source /opt/ros/foxy/(local_)setup.zsh first and then ~/ws/install/local_setup.zsh
• In simpler words, if you source local_setup.zsh of the overlay, it will only consider the packages available in the overlay when adding to the environment. setup.zsh will source the underlay and then the overlay, giving you an environment with both workspaces in it.

Learning about Docker

What does xhost +"local:docker@" do?
This permits the docker user on the local machine to connect to X windows display.

This is usually required in intel machines. For nvidia systems, mounting /tmp/.X11-unix as a volume suffices.

References