Launch file for running gzserver (#532)

* Launch file for the bridge

Signed-off-by: Carlos Agüero <caguero@openrobotics.org>

ros_gz_sim/CMakeLists.txt

@@ -120,6 +120,7 @@ install(FILES
 )
 
 install(FILES
+  "launch/gz_server.launch.py"
   "launch/ros_gz_sim.launch.py"
   DESTINATION share/${PROJECT_NAME}/launch
 )

ros_gz_sim/launch/gz_server.launch.py

@@ -0,0 +1,91 @@
+# Copyright 2024 Open Source Robotics Foundation, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Launch gzserver in a component container."""
+
+from launch import LaunchDescription
+from launch.actions import DeclareLaunchArgument, GroupAction
+from launch.conditions import IfCondition
+from launch.substitutions import LaunchConfiguration, PythonExpression, TextSubstitution
+from launch_ros.actions import ComposableNodeContainer, Node
+from launch_ros.descriptions import ComposableNode
+
+
+def generate_launch_description():
+
+    world_sdf_file = LaunchConfiguration('world_sdf_file')
+    world_sdf_string = LaunchConfiguration('world_sdf_string')
+    container_name = LaunchConfiguration('container_name')
+    use_composition = LaunchConfiguration('use_composition')
+
+    declare_world_sdf_file_cmd = DeclareLaunchArgument(
+        'world_sdf_file', default_value=TextSubstitution(text=''),
+        description='Path to the SDF world file')
+    declare_world_sdf_string_cmd = DeclareLaunchArgument(
+        'world_sdf_string', default_value=TextSubstitution(text=''),
+        description='SDF world string')
+    declare_container_name_cmd = DeclareLaunchArgument(
+        'container_name',
+        default_value='ros_gz_container',
+        description='Name of container that nodes will load in if use composition',
+    )
+    declare_use_composition_cmd = DeclareLaunchArgument(
+        'use_composition', default_value='False', description='Use composed bringup if True'
+    )
+
+    load_nodes = GroupAction(
+        condition=IfCondition(PythonExpression(['not ', use_composition])),
+        actions=[
+            Node(
+                package='ros_gz_sim',
+                executable='gzserver',
+                output='screen',
+                parameters=[{'world_sdf_file': world_sdf_file,
+                             'world_sdf_string': world_sdf_string}],
+            ),
+        ],
+    )
+
+    load_composable_nodes = ComposableNodeContainer(
+        condition=IfCondition(use_composition),
+        name=container_name,
+        namespace='',
+        package='rclcpp_components',
+        executable='component_container',
+        composable_node_descriptions=[
+            ComposableNode(
+                package='ros_gz_sim',
+                plugin='ros_gz_sim::GzServer',
+                name='gzserver',
+                parameters=[{'world_sdf_file': world_sdf_file,
+                             'world_sdf_string': world_sdf_string}],
+                extra_arguments=[{'use_intra_process_comms': True}],
+            ),
+        ],
+        output='screen',
+    )
+
+    # Create the launch description and populate
+    ld = LaunchDescription()
+
+    # Declare the launch options
+    ld.add_action(declare_world_sdf_file_cmd)
+    ld.add_action(declare_world_sdf_string_cmd)
+    ld.add_action(declare_container_name_cmd)
+    ld.add_action(declare_use_composition_cmd)
+    # Add the actions to launch all of the gzserver nodes
+    ld.add_action(load_nodes)
+    ld.add_action(load_composable_nodes)
+
+    return ld