rover-ros2/src/anchor_pkg/launch/rover.launch.py

#!/usr/bin/env python3

from launch import LaunchDescription
from launch.actions import DeclareLaunchArgument, OpaqueFunction, Shutdown
from launch.substitutions import (
    LaunchConfiguration,
    ThisLaunchFileDir,
    PathJoinSubstitution,
)
from launch_ros.actions import Node
from launch.conditions import IfCondition


# Prevent making __pycache__ directories
from sys import dont_write_bytecode

dont_write_bytecode = True


def launch_setup(context, *args, **kwargs):
    # Retrieve the resolved value of the launch argument 'mode'
    mode = LaunchConfiguration("mode").perform(context)
    nodes = []

    if mode == "anchor":
        # Launch every node and pass "anchor" as the parameter

        nodes.append(
            Node(
                package="arm_pkg",
                executable="arm",  # change as needed
                name="arm",
                output="both",
                parameters=[{"launch_mode": mode}],
                on_exit=Shutdown(),
            )
        )
        nodes.append(
            Node(
                package="core_pkg",
                executable="core",  # change as needed
                name="core",
                output="both",
                parameters=[{"launch_mode": mode}],
                on_exit=Shutdown(),
            )
        )
        nodes.append(
            Node(
                package="core_pkg",
                executable="ptz",  # change as needed
                name="ptz",
                output="both",
                condition=IfCondition(LaunchConfiguration("use_ptz", default="true")),
                # Currently don't shutdown all nodes if the PTZ node fails, as it is not critical
                # on_exit=Shutdown()  # Uncomment if you want to shutdown on PTZ failure
            )
        )
        nodes.append(
            Node(
                package="bio_pkg",
                executable="bio",  # change as needed
                name="bio",
                output="both",
                parameters=[{"launch_mode": mode}],
                on_exit=Shutdown(),
            )
        )
        nodes.append(
            Node(
                package="anchor_pkg",
                executable="anchor",  # change as needed
                name="anchor",
                output="both",
                parameters=[{"launch_mode": mode}],
                on_exit=Shutdown(),
            )
        )
    elif mode in ["arm", "core", "bio", "ptz"]:
        # Only launch the node corresponding to the provided mode.
        if mode == "arm":
            nodes.append(
                Node(
                    package="arm_pkg",
                    executable="arm",
                    name="arm",
                    output="both",
                    parameters=[{"launch_mode": mode}],
                    on_exit=Shutdown(),
                )
            )
        elif mode == "core":
            nodes.append(
                Node(
                    package="core_pkg",
                    executable="core",
                    name="core",
                    output="both",
                    parameters=[{"launch_mode": mode}],
                    on_exit=Shutdown(),
                )
            )
        elif mode == "bio":
            nodes.append(
                Node(
                    package="bio_pkg",
                    executable="bio",
                    name="bio",
                    output="both",
                    parameters=[{"launch_mode": mode}],
                    on_exit=Shutdown(),
                )
            )
        elif mode == "ptz":
            nodes.append(
                Node(
                    package="core_pkg",
                    executable="ptz",
                    name="ptz",
                    output="both",
                    on_exit=Shutdown(),  # on fail, shutdown if this was the only node to be launched
                )
            )
    else:
        # If an invalid mode is provided, print an error.
        print("Invalid mode provided. Choose one of: arm, core, bio, anchor, ptz.")

    return nodes


def generate_launch_description():
    declare_arg = DeclareLaunchArgument(
        "mode",
        default_value="anchor",
        description="Launch mode: arm, core, bio, anchor, or ptz",
    )

    return LaunchDescription([declare_arg, OpaqueFunction(function=launch_setup)])