Bag Recorder Backend

A ROS2 bag recorder backend with a REST API for controlling bag recordings. Designed as a simple developer tool for recording ROS topics into bag files via a web interface.

Features

• REST API for controlling bag recordings (start/stop/list/download/delete)
• Generic topic recording - records any ROS2 message type without type-specific code
• Batch operations - download or delete multiple recordings at once
• CORS support - easily connect from a separate frontend application

Requirements

• ROS2 (Humble or later recommended)
• Crow C++ web framework
• nlohmann/json (header-only, typically included with Crow)

Installation

Docker Build

cd bag_recorder_backend
docker build -t bag_recorder_backend .

Usage

Running with Docker

# Basic run (connects to host ROS2 network)
docker run --rm -it \
  --network host \
  -v /tmp/rosbags:/tmp/rosbags \
  bag_recorder_backend

# With custom output directory
docker run --rm -it \
  --network host \
  -v /path/to/bags:/bags \
  -e OUTPUT_DIR=/bags \
  bag_recorder_backend

# With custom port
docker run --rm -it \
  --network host \
  -e SERVER_PORT=9090 \
  bag_recorder_backend

API Reference

REST Endpoints

Method	Endpoint	Description
GET	/api/status	Get current recording status
GET	/api/topics	List available ROS topics
POST	/api/recording/start	Start a new recording
POST	/api/recording/stop	Stop current recording
GET	/api/config	Get server configuration
POST	/api/config	Update server configuration
GET	/api/recordings	List all recorded bag files
DELETE	/api/recordings/<name>	Delete a recording
GET	/api/recordings/<name>/download	Download recording as tar.gz
POST	/api/recordings/download	Download multiple recordings
POST	/api/recordings/delete	Delete multiple recordings

API Examples

Start Recording:

curl -X POST http://localhost:8080/api/recording/start \
  -H "Content-Type: application/json" \
  -d '{
    "topics": ["/camera/image_raw", "/imu/data"],
    "output_path": "/tmp/rosbags/my_recording"
  }'

Stop Recording:

curl -X POST http://localhost:8080/api/recording/stop

Get Status:

curl http://localhost:8080/api/status

List Recordings:

curl http://localhost:8080/api/recordings

Download Recording:

curl -O http://localhost:8080/api/recordings/recording_20231215_143022/download

Delete Recording:

curl -X DELETE http://localhost:8080/api/recordings/recording_20231215_143022

Configuration

Configuration is done via ROS2 parameters:

Parameter	Default	Description
server_port	8080	HTTP server port
output_directory	/tmp/rosbags	Default bag output directory
enable_cors	true	Enable CORS headers for frontend

See config/config.yaml for the full configuration file.

Architecture

┌─────────────────────────────────────────────────────────┐
│                      main.cpp                           │
│         (initialization, signal handling)               │
└─────────────────────┬───────────────────────────────────┘
                      │
        ┌─────────────┴─────────────┐
        │                           │
        ▼                           ▼
┌───────────────────┐      ┌────────────────────┐
│  BagRecorderNode  │◄────►│    CrowServer      │
│   (ROS2 node)     │      │    (HTTP API)      │
│                   │      │                    │
│ - Topic discovery │      │ - REST API routes  │
│ - Bag writing     │      │ - CORS handling    │
│ - Subscriptions   │      │                    │
└───────────────────┘      └────────────────────┘

License

MIT License