Launchers

As previously described, the launchers/ directory contains entry scripts for Docker containers spawned from a DTProject image.

Attention

If you are familiar with Docker.

We purposefully refer to these scripts as entry scripts as not to confuse them with entrypoints as they are defined by Docker. In fact, launcher scripts will not be directly used as container entrypoints. A generic entrypoint is defined in all Duckietown images and is used to configure the containers’ network, environment, etc.

The default launcher

Every project template includes a launcher file called default.sh, which runs when executing dts devel run. Modify this script to launch the main behavior, for example, an autonomous lane-following pipeline.

While having a default launcher is great, often projects can use more than a single entry point.

Additional launchers can exercise individual components or tests. For example, leave default.sh unchanged for the full pipeline and create camera-intrinsic-calibration.sh, camera-extrinsic-calibration.sh, etc., to perform specific camera calibrations.

Add new launchers

To add a launcher, create a file in launchers/ with either a .sh extension or a valid shebang on the first line.

For example, this Python script file launchers/my-launcher.py can be a launcher:

#!/usr/bin/env python3

message = "This is a Python launcher"
print(message)

Note

After dts devel build, the output lists installed launchers:

...
-------------------------
Image launchers:
 - default
 - test-agent
 - test-lens-distortion
-------------------------

Launchers inside the container

Launchers inside the container appear as shell commands named as dt-launcher-<LAUNCHER_NAME>. For example, the launcher file launchers/my-launcher.sh will be available as the shell command dt-launcher-my-launcher.