Update launch file to support global launch file (#32)

* Rename example.py and fixed invalid Node name-value parameters

* Add TODO for global config

* Rename launch file to main_launch.py

* Support global launch file

* Overhaul launch file with new global launch file format

* Resolve merge conflict... again

* Load in global launch arguments rather than store them in file

* Add environment variable to color ROS logs

* Ignore python binary files

* Update global_launch dir path

* Create variable for node name

* Rework env vars

* Move global_launch dir back to src

* Remove local enviornment variables

---------

Co-authored-by: Patrick Creighton <[email protected]>

.gitignore

@@ -1,2 +1,3 @@
 # autogenerated files
 lib/cmn_hdrs/ros_info.h
+*.pyc

launch/main_launch.py

@@ -1,75 +1,96 @@
+"""Launch file that runs all nodes for the network systems ROS package."""
+
 import importlib
 import os
-from types import ModuleType
 from typing import List
 
 from launch_ros.actions import Node
 
-from launch import LaunchDescription
+from launch import LaunchDescription, LaunchDescriptionEntity
+from launch.actions import OpaqueFunction
+from launch.launch_context import LaunchContext
 from launch.substitutions import LaunchConfiguration
 
+# Local launch arguments and constants
+PACKAGE_NAME = "network_systems"
+
+# Add args with DeclareLaunchArguments object(s) and utilize in setup_launch()
+LOCAL_LAUNCH_ARGUMENTS = []
 
-def get_global_main_launch_module() -> ModuleType:
-    """Execute and return the main launch file of the `global_launch` package.
+
+def generate_launch_description() -> LaunchDescription:
+    """The launch file entry point. Generates the launch description for the `network_systems`
+    package.
 
     Returns:
-        ModuleType: The executed module.
+        LaunchDescription: The launch description.
+    """
+    global_launch_arguments, global_environment_vars = get_global_launch_arguments()
+    return LaunchDescription(
+        [
+            *global_launch_arguments,
+            *global_environment_vars,
+            *LOCAL_LAUNCH_ARGUMENTS,
+            OpaqueFunction(function=setup_launch),
+        ]
+    )
+
+
+def get_global_launch_arguments() -> List[LaunchDescriptionEntity]:
+    """Gets the global launch arguments defined in the global launch file.
+
+    Returns:
+        List[LaunchDescriptionEntity]: List of global launch argument objects.
     """
     global_main_launch = os.path.join(
         os.getenv("ROS_WORKSPACE"), "src", "global_launch", "main_launch.py"
     )
     spec = importlib.util.spec_from_file_location("global_launch", global_main_launch)
     module = importlib.util.module_from_spec(spec)
     spec.loader.exec_module(module)
-    return module
-
+    global_launch_arguments = module.GLOBAL_LAUNCH_ARGUMENTS
+    global_environment_vars = module.ENVIRONMENT_VARIABLES
+    return global_launch_arguments, global_environment_vars
 
-GLOBAL_LAUNCH = get_global_main_launch_module()
 
+def setup_launch(context: LaunchContext) -> List[LaunchDescriptionEntity]:
+    """Collects launch descriptions that describe the system behavior in the `network_systems`
+    package.
 
-def generate_launch_description() -> LaunchDescription:
-    """Generate the launch description for the `local_pathfinding` package.
+    Args:
+        context (LaunchContext): The current launch context.
 
     Returns:
-        LaunchDescription: The launch description.
+        List[LaunchDescriptionEntity]: Launch descriptions.
     """
-    # get_nodes() arguments for the package launch
-    common_parameters = [GLOBAL_LAUNCH.GLOBAL_CONFIG]
-    common_ros_arguments = [*GLOBAL_LAUNCH.get_log_ros_arguments()]
-    mode = LaunchConfiguration("mode")
-
-    return LaunchDescription(
-        [
-            *GLOBAL_LAUNCH.GLOBAL_LAUNCH_ARGUMENTS,
-            *get_nodes(common_parameters, common_ros_arguments, mode),
-        ]
-    )
+    launch_description_entities = list()
+    launch_description_entities.append(get_cached_fib_description(context))
+    return launch_description_entities
 
 
-def get_nodes(common_parameters: List, common_ros_arguments: List, mode: str) -> List[Node]:
-    """Get the nodes to be launched depending on an indicated mode.
+def get_cached_fib_description(context: LaunchContext) -> Node:
+    """Gets the launch description for the cached_fib node.
 
     Args:
-        common_parameters (List): Parameters that are common to all nodes.
-        common_ros_arguments (List): ROS arguments that are common to all nodes.
-        mode (str): The system mode.
+        context (LaunchContext): The current launch context.
 
     Returns:
-        List[Node]: The nodes to be launched.
+        Node: The node object that launches the cached_fib node.
     """
-    # cached_fib parameters and ROS arguments
-    cached_fib_parameters = [*common_parameters]
-    cached_fib_ros_arguments = [*common_ros_arguments]
-
-    nodes = [
-        Node(
-            package="network_systems",
-            namespace="example",
-            executable="example",
-            name="cached_fib",
-            parameters=cached_fib_parameters,
-            ros_arguments=cached_fib_ros_arguments,
-        ),
+    node_name = "cached_fib"
+    ros_parameters = [LaunchConfiguration("config").perform(context)]
+    ros_arguments = [
+        "--log-level",
+        [f"{node_name}:=", LaunchConfiguration("log_level")],
     ]
 
-    return nodes
+    node = Node(
+        package=PACKAGE_NAME,
+        namespace="example",
+        executable="example",
+        name=node_name,
+        parameters=ros_parameters,
+        ros_arguments=ros_arguments,
+    )
+
+    return node