Parameter from YAML file cannot be overridden

[felixdivo]

Bug report

Required Info:

• Operating System:
  • Ubuntu 20.04
• Installation type:
  • binary via apt
• Version or commit hash:
  • Latest available Foxy @ 0.10.5-1focal.20210423.000156
• DDS implementation:
  • default
• Client library (if applicable):
  • not relevant (rclpy)

Steps to reproduce issue

1. Create example_launch.py:

#!/usr/bin/env python3

from launch import LaunchDescription
from launch_ros.actions import Node

def generate_launch_description() -> LaunchDescription:
    return LaunchDescription(
        [
            Node(
                package="turtlesim",
                executable="turtlesim_node",
                name="turtlesim_node",
                parameters=[
                    {"background_b": 200},  # should have no effect
                    "parameters.yaml",  # should override the default value
                    {"background_b": 200},  # should override the value 5 from the previous line
                ],
            ),
        ]
    )

2. Create parameters.yaml:

turtlesim_node:
  ros__parameters:

    background_b: 5

3. Start with ros2 launch example_launch.py.

4. Check the param in another terminal: ros2 param get turtlesim_node background_b.

Expected behavior

Output Integer value is: 200.

Actual behavior

Output Integer value is: 5.

Additional information

The documentation states that parameters declared later shall override prior ones.

[felixdivo]

I just realized that this is probably the wrong repo. Re-opened here: https://github.com/ros2/launch_ros/issues/233