ROS Bag Loader

Download ROS bag files using JIT (Just-In-Time) manifest with presigned URLs.

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Plugin: rosbag-loader Group: Core / ROS

Task Type
dev.bringup.plugin.core.rosbag.LoadById

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Overview

The ROS Bag Loader is a specialized task for downloading ROS bag files from cloud storage. It uses a JIT manifest system with presigned URLs to securely download bag files without requiring permanent credentials.

When a flow has inputs matching rosbag naming conventions (e.g., rosbag_id), the Flow Service can automatically insert a LoadById task at the beginning of the flow.

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Examples

Basic rosbag loading

id: load-rosbag
namespace: robotics
description: Download and inspect a ROS bag file

inputs:
  - id: rosbag_id
    type: STRING
    required: true
    description: The ID of the rosbag to download

variables:
  BM_ROSBAGS_DIR: /tmp/bagmaster/rosbags
  BM_ROSBAGS_MANIFEST_PATH: /tmp/bagmaster/rosbags/manifest.json

tasks:
  - id: bm_rosbag_loader
    type: dev.bringup.plugin.core.rosbag.LoadById

  - id: inspect
    type: dev.bringup.plugin.core.shell.Shell
    commands:
      - ls -la ${BM_ROSBAGS_DIR}
      - cat ${BM_ROSBAGS_MANIFEST_PATH}
      - echo "Rosbag files downloaded successfully"

Rosbag with Python analysis

id: rosbag-analysis
namespace: analytics
description: Download a rosbag and analyze its contents

inputs:
  - id: rosbag_id
    type: STRING
    required: true

variables:
  BM_ROSBAGS_DIR: /tmp/bagmaster/rosbags
  BM_ROSBAGS_MANIFEST_PATH: /tmp/bagmaster/rosbags/manifest.json

tasks:
  - id: bm_rosbag_loader
    type: dev.bringup.plugin.core.rosbag.LoadById

  - id: analyze
    type: dev.bringup.plugin.scripts.python.Script
    dependencies:
      - rosbags
    script: |
      import json
      import os

      manifest_path = os.getenv("BM_ROSBAGS_MANIFEST_PATH")
      with open(manifest_path) as f:
          manifest = json.load(f)

      entries = manifest.get("entries", [])
      print(f"Downloaded {len(entries)} rosbag files:")
      for entry in entries:
          print(f"  - {entry.get('filename', 'unknown')}")
          print(f"    Size: {entry.get('size', 'unknown')} bytes")

Custom target directory

tasks:
  - id: bm_rosbag_loader
    type: dev.bringup.plugin.core.rosbag.LoadById
    targetDir: /workspace/custom-bags
    overwrite: true

With overwrite control

tasks:
  - id: bm_rosbag_loader
    type: dev.bringup.plugin.core.rosbag.LoadById
    targetDir: '${BM_ROSBAGS_DIR}'
    manifestPath: '${BM_ROSBAGS_MANIFEST_PATH}'
    overwrite: false

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Properties

targetDir

Type	string
Required	No
Default	"${BM_ROSBAGS_DIR}"
Description	Directory where rosbag files will be downloaded. Defaults to the BM_ROSBAGS_DIR environment variable, typically /tmp/bagmaster/rosbags.

manifestPath

Type	string
Required	No
Default	"${BM_ROSBAGS_MANIFEST_PATH}"
Description	Path where the JIT manifest JSON file will be written. The manifest contains metadata about downloaded files including their paths and sizes.

overwrite

Type	boolean
Required	No
Default	true
Description	Whether to overwrite existing rosbag files in the target directory. Set to false to skip downloading files that already exist.

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Common Task Properties

See Shell > Common Task Properties for id, type, description, disabled, timeout, retry, allow_failure, run_if, and worker_group.

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Auto-Insertion

The Flow Service automatically inserts a LoadById task when it detects rosbag-related inputs in a flow. The detection is convention-based:

• Input IDs matching rosbag patterns (e.g., rosbag_id) trigger automatic insertion
• The loader task is placed at the beginning of the task list
• Required variables (BM_ROSBAGS_DIR, BM_ROSBAGS_MANIFEST_PATH) are added to the flow

This means you can sometimes omit the loader task entirely if your flow follows naming conventions:

# The loader task will be auto-inserted before 'process'
id: auto-load-example
namespace: robotics
inputs:
  - id: rosbag_id
    type: STRING
tasks:
  - id: process
    type: dev.bringup.plugin.core.shell.Shell
    commands:
      - echo "Rosbag is already available at ${BM_ROSBAGS_DIR}"

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Notes

• The rosbag loader requires network access to the Bringup cloud storage endpoint.
• Presigned URLs have a limited validity window; flows should be executed promptly after creation.
• The manifest file (manifest.json) contains metadata about all downloaded files, useful for downstream tasks.
• Large rosbag files may require extended timeouts on the task.