hexapod_robot/bringup/launch/hexapod_robot.launch.py

from launch import LaunchDescription
from launch.substitutions import Command, FindExecutable, LaunchConfiguration, PathJoinSubstitution

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

def generate_launch_description():
    
    robot_description_content = Command([
            PathJoinSubstitution([FindExecutable(name="xacro")]),
            " ",
            PathJoinSubstitution(
                [
                    FindPackageShare("hexapod_robot"),
                    "urdf",
                    "hexapod_robot.urdf.xacro"
                ]
            )
        ]
    )
    robot_description = {"robot_description": robot_description_content}
            
    rviz_node = Node(
        package="rviz2",
        executable="rviz2",
        arguments=['-d', PathJoinSubstitution([FindPackageShare("hexapod_robot"), "config", "hexapod_robot.rviz"])],
        name="rviz2",
        output="screen",
    )
            
    robot_state_publisher_node = Node(
        package="robot_state_publisher",
        executable="robot_state_publisher",
        parameters=[{
            'robot_description': robot_description_content
        }]
    )            

    joint_state_publisher_gui = Node(
        package="joint_state_publisher_gui",
        executable="joint_state_publisher_gui"
    )
            
    nodes = [
        rviz_node,
        robot_state_publisher_node,
        joint_state_publisher_gui
        
    ]
            
    return LaunchDescription(nodes)