ROS 2 Node Launcher from Hierarchical YAML

This script provides a flexible and reusable way to launch a ROS 2 node from a hierarchical YAML configuration file.
It is designed to be copied directly into your bringup package and used from your launch files — no installation or packaging required.

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Features

• Launch any ROS 2 node from a structured YAML config
• Support for nested namespaces
• Remappings directly from YAML: topics, services, and actions
• Automatic path resolution for package:// and file:// URIs
• Node execution options: respawn, emulate TTY, shutdown on exit
• Drop-in integration: no setup.py, no pip install

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YAML Structure

my_ns:
  sub_ns:
    my_node:
      ros__parameters:
        param_1: true
        param_2: 42
        camera_config: package://my_robot_description/config/camera.yaml
        static_file: file:///home/user/data/fixed_params.yaml
        ros_remappings:
          topics:
            - "/camera/image_raw:/namespace/image_raw"
          services:
            - "/get_status:/namespace/get_status"
          actions:
            - "/navigate_to_pose:/namespace/navigate_to_pose"
        ros_execution:
          node_package: my_package
          node_executable: my_node_exec
          output: screen
          emulate_tty: true
          respawn: true
          respawn_delay: 2.0
          on_node_exit_shutdown_system: true

This structure defines:

• A nested namespace: my_ns/sub_ns
• A node named my_node
• Parameters under ros__parameters
• Remappings for topics, services, and actions
• Execution behavior under ros_execution

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Remapping behavior

Remappings are grouped by interface type:

• topics: list of "from:to" strings

• services: same format as topics

• actions: automatically expanded into five ROS 2 subtopics:

  • _action/feedback
  • _action/status
  • _action/cancel_goal
  • _action/get_result
  • _action/send_goal

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Path resolution

This tool resolves paths using common URI-style prefixes:

• package://my_pkg/config/my_file.yaml → resolved to ${AMENT_PREFIX_PATH}/share/my_pkg/config/my_file.yaml

• file:///home/user/some/path/file.yaml → resolved directly to /home/user/some/path/file.yaml

This is useful for loading external configuration files in parameters.

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Contact

For any questions or suggestions, please reach out to:

Juan Francisco Rascon
Email: jfrascon@gmail.com