The driver source lives in lidar/sllidar_ros2/ as a git subtree of this repository. The Dockerfile copies it directly from the workspace — no network access is required at build time.

Workspace repo                Docker build
──────────────────────────    ──────────────────────────────────────────
lidar/sllidar_ros2/      ───> COPY lidar/sllidar_ros2/ src/sllidar_ros2/
(git subtree of fork)         colcon build --packages-select sllidar_ros2

The upstream fork is maintained at:

https://github.com/m5p3nc3r/sllidar_ros2

Development workflow

Pulling upstream changes into the workspace

git subtree pull --prefix=lidar/sllidar_ros2 sllidar_ros2 main --squash

This fetches the latest commits from the fork, squashes them into a single merge commit, and updates lidar/sllidar_ros2/ in the workspace.

Making local changes

Edit files inside lidar/sllidar_ros2/ as normal, then commit them to the workspace repo:

git add lidar/sllidar_ros2/
git commit -m "lidar: describe the change"

Pushing changes back to the fork

git subtree push --prefix=lidar/sllidar_ros2 sllidar_ros2 main

This replays only the commits that touched lidar/sllidar_ros2/ and pushes them to the fork's main branch.

First-time setup on a fresh clone

The subtree files are committed in the workspace repo, so a git clone of this repo is all that is needed — there is no separate step to initialise the subtree. To be able to pull or push to the fork later, add the remote:

git remote add sllidar_ros2 https://github.com/m5p3nc3r/sllidar_ros2.git

Changes relative to upstream

File	Change
`src/sllidar_node.cpp`	`/scan` publisher QoS made configurable via `scan_qos_depth` (int) and `scan_qos_reliability` (`best_effort`\|`reliable`) parameters. Defaults to `best_effort`, depth 2 — required for Nav2 / RViz2 compatibility.
`launch/sllidar_a1_launch.py`	Exposes `scan_qos_depth` and `scan_qos_reliability` as launch arguments.

The upstream Slamtec repository is at:

https://github.com/slamtec/sllidar_ros2

Published topics

Topic	Type	Description
`/scan`	`sensor_msgs/LaserScan`	360° laser scan, `BEST_EFFORT` QoS, depth 2

Device

The RPLIDAR A1 connects via USB serial at /dev/ttyUSB0 (default), 115200 baud. The container receives access to that device via the devices mapping in docker-compose.yml. To use a different port, set LIDAR_PORT in your .env file:

LIDAR_PORT=/dev/ttyUSB1