servo/ros2_environment/src/rbs_servo_test/launch/startup.launch.py

from launch import LaunchDescription
from launch.actions import DeclareLaunchArgument, RegisterEventHandler, OpaqueFunction
from launch.conditions import IfCondition
from launch.event_handlers import OnProcessExit
from launch.substitutions import Command, FindExecutable, LaunchConfiguration, PathJoinSubstitution

from launch_ros.actions import Node, node
from launch_ros.substitutions import FindPackageShare


def launch_setup(context, *args, **kwargs):
    # Initialize Arguments
    robot_controller = LaunchConfiguration("robot_controller")
    gui = LaunchConfiguration("gui")
    filepath = PathJoinSubstitution(
        [
            FindPackageShare("rbs_servo_test"),
            "urdf",
            "simple_robot.urdf"
        ]
    ).perform(context)

    with open(filepath, "r") as file:
        robot_description_content = file.read()

    robot_description = {"robot_description": robot_description_content}

    robot_controllers = PathJoinSubstitution(
        [
            FindPackageShare("rbs_servo_test"),
            "config",
            "ros2_controllers.yaml",
        ]
    )
    rviz_config_file = PathJoinSubstitution(
        [FindPackageShare("rbs_servo_test"), "config", "driver.rviz"]
    )

    control_node = Node(
        package="controller_manager",
        # prefix=['gdbserver localhost:1234'],
        executable="ros2_control_node",
        parameters=[robot_description, robot_controllers],
        output="both",
    )
    robot_state_pub_node = Node(
        package="robot_state_publisher",
        executable="robot_state_publisher",
        output="both",
        parameters=[robot_description],
    )
    rviz_node = Node(
        package="rviz2",
        executable="rviz2",
        name="rviz2",
        output="log",
        # arguments=["-d", rviz_config_file],
        condition=IfCondition(gui),
    )

    joint_state_broadcaster_spawner = Node(
        package="controller_manager",
        executable="spawner",
        arguments=["joint_state_broadcaster", "--controller-manager", "/controller_manager"],
    )

    robot_controller_spawner = Node(
        package="controller_manager",
        executable="spawner",
        arguments=[robot_controller, "--controller-manager", "/controller_manager"],
    )

    # Delay rviz start after `joint_state_broadcaster`
    delay_rviz_after_joint_state_broadcaster_spawner = RegisterEventHandler(
        event_handler=OnProcessExit(
            target_action=joint_state_broadcaster_spawner,
            on_exit=[rviz_node],
        )
    )

    # Delay start of robot_controller after `joint_state_broadcaster`
    delay_robot_controller_spawner_after_joint_state_broadcaster_spawner = RegisterEventHandler(
        event_handler=OnProcessExit(
            target_action=joint_state_broadcaster_spawner,
            on_exit=[robot_controller_spawner],
        )
    )

    nodes = [
        control_node,
        robot_state_pub_node,
        joint_state_broadcaster_spawner,
        delay_rviz_after_joint_state_broadcaster_spawner,
        delay_robot_controller_spawner_after_joint_state_broadcaster_spawner,
    ]
    return nodes


def generate_launch_description():
    # Declare arguments
    declared_arguments = []
    declared_arguments.append(
        DeclareLaunchArgument(
            "gui",
            default_value="false",
            description="Start RViz2 automatically with this launch file.",
        )
    
    )

    declared_arguments.append(
        DeclareLaunchArgument(
            "robot_controller",
            default_value="forward_position_controller",
            description=".......",
        )
    )


    return LaunchDescription(declared_arguments + [OpaqueFunction(function=launch_setup)])