launch_ros action to set parameters for all nodes in scope using a global parameter yaml file

[adityapande-1995]

This PR aims to add a new launch_ros action, SetParametersFromFile which can accept a yaml file with ROS parameters which can be passed to all nodes in scope.

Example usage :

The parameter file:

The parameter yaml file must be written in the following format:

demo_node_1:
  ros__parameters:
    param_1: 1
    param_2: 5

demo_node_2:
  ros__parameters:
    param_2: 10
    param_4: hello_world

Launch file in xml:

demo_node_3 is not in the same scope, so the SetParametesFromFile action won't affect it.

<launch>
  <group>
    <set_parameters_from_file filename='/path/to/param/file.yaml'>
    <node pkg="demo_nodes_cpp" exec="parameter_blackboard" name="demo_node_1">
    <node pkg="demo_nodes_cpp" exec="parameter_blackboard" name="demo_node_2">
  </group>
  <node pkg="demo_nodes_cpp" exec="parameter_blackboard" name="demo_node_3">
</launch>

Equivalent usage in python:

from launch import LaunchDescription
from launch_ros.actions import Node, SetParametersFromFile
from launch.actions import GroupAction

def generate_launch_description():
  return LaunchDescription([
     GroupAction(
       actions = [
          SetParametersFromFile('path/to/yaml/file.yaml'),

          Node(
            package = 'demo_nodes_cpp',
            executable = 'parameter_blackboard',
            name = 'demo_node_1'
          ),

          Node(
            package = 'demo_nodes_cpp',
            executable = 'parameter_blackboard',
            name = 'demo_node_2'
          )
        ]
      ),

       Node(
          package = 'demo_nodes_cpp',
          executable = 'parameter_blackboard',
          name = 'demo_node_3'
        )
  ])

TODO

• Add test cases
• Are @property methods required for SetParametersFromFile class ? For e.g.

  launch_ros/launch_ros/launch_ros/actions/set_parameter.py

  Line 76 in ef1502e

  @property

• Cleaner / better way to extract raw text from SomeSubstitutionType objects when parsing xml launch files

[ivanpauno]

This is only adding the parameterers to Node actions but not to loaded components, which might be a bit unexpected by users.
Maybe we can fix that after #259 is merged.

[adityapande-1995]

TODO

• Add action to composable nodes, waiting for Support both parameter file configurations for composable nodes #259
• Add a test case

[adityapande-1995]

Parameters are now passed in order , e.g. this launch file

<launch>
	<group>
		<set_parameters_from_file filename="/home/aditya/LaunchTest/params.yaml"/>
		<set_parameter name="test_param" value="10"/>
		<set_parameters_from_file filename="/home/aditya/LaunchTest/params2.yaml"/>
		<set_parameter name="test_param2" value="10"/>
		<node pkg="demo_nodes_cpp" exec="parameter_blackboard" name="demo_node_1" namespace="ns1"/>
		<node pkg="demo_nodes_cpp" exec="parameter_blackboard" name="demo_node_2"/>
	</group>
		<node pkg="demo_nodes_cpp" exec="parameter_blackboard" name="demo_node_3"/>
</launch>

will run --

aditya@qemu-ubuntu:~/LaunchTest$ ps auxww | grep blackboard | cut -c 60-
   0:00 /home/aditya/ros2_rolling/install/demo_nodes_cpp/lib/demo_nodes_cpp/parameter_blackboard --ros-args -r __node:=demo_node_1 -r __ns:=/ns1 --params-file /home/aditya/LaunchTest/params.yaml -p test_param:=10 --params-file /home/aditya/LaunchTest/params2.yaml -p test_param2:=10
   0:00 /home/aditya/ros2_rolling/install/demo_nodes_cpp/lib/demo_nodes_cpp/parameter_blackboard --ros-args -r __node:=demo_node_2 --params-file /home/aditya/LaunchTest/params.yaml -p test_param:=10 --params-file /home/aditya/LaunchTest/params2.yaml -p test_param2:=10
   0:00 /home/aditya/ros2_rolling/install/demo_nodes_cpp/lib/demo_nodes_cpp/parameter_blackboard --ros-args -r __node:=demo_node_3
   0:00 grep --color=auto blackboard

Similarly,

def generate_launch_description():
    return LaunchDescription([

        GroupAction(
            actions = [
                SetParametersFromFile('/home/aditya/LaunchTest/params.yaml'),
		SetParameter(name = 'test_param', value = 10),
                SetParametersFromFile('/home/aditya/LaunchTest/params2.yaml'),
		SetParameter(name = 'test_param2', value = 10),

                Node(
                    package = 'demo_nodes_cpp',
                    executable = 'parameter_blackboard',
                    name = 'demo_node_1',
					namespace = 'ns1'
                    ),

                Node(
                    package = 'demo_nodes_cpp',
                    executable = 'parameter_blackboard',
                    name = 'demo_node_2',
		    parameters = [{'param_10':10}]
                    )
                ]
            ),

    Node(
        package = 'demo_nodes_cpp',
        executable = 'parameter_blackboard',
        name = 'demo_node_3'
        )
    
    ])

will produce:

aditya@qemu-ubuntu:~/LaunchTest$ ps auxww | grep blackboard | cut -c 60-
   0:00 /home/aditya/ros2_rolling/install/demo_nodes_cpp/lib/demo_nodes_cpp/parameter_blackboard --ros-args -r __node:=demo_node_1 -r __ns:=/ns1 --params-file /home/aditya/LaunchTest/params.yaml -p test_param:=10 --params-file /home/aditya/LaunchTest/params2.yaml -p test_param2:=10
   0:00 /home/aditya/ros2_rolling/install/demo_nodes_cpp/lib/demo_nodes_cpp/parameter_blackboard --ros-args -r __node:=demo_node_2 --params-file /home/aditya/LaunchTest/params.yaml -p test_param:=10 --params-file /home/aditya/LaunchTest/params2.yaml -p test_param2:=10 --params-file /tmp/launch_params_s1x0dxst
   0:00 /home/aditya/ros2_rolling/install/demo_nodes_cpp/lib/demo_nodes_cpp/parameter_blackboard --ros-args -r __node:=demo_node_3
   0:00 grep --color=auto blackboard

TODO

• Fix broken test cases for SetParameter
• Add new tests for SetParametesFromFile

[ivanpauno]

Implementation LGTM!
This looks ready to go with some tests added.

[ivanpauno]

LGTM!

[ivanpauno]

LGTM with green CI

[jacobperron]

LGTM! Just a couple minor comments.

[adityapande-1995]

CI :

• Linux
• Linux-aarch64
• macOS
• Windows