Add launch file

NODE
It has the same problem as following link
ros2/launch#204

All nodes have the same node name...

CMakeLists.txt

@@ -67,6 +67,11 @@ install(TARGETS
   RUNTIME DESTINATION bin
 )
 
+#install other files
+install(DIRECTORY launch
+  DESTINATION share/${PROJECT_NAME}/
+)
+
 # install executables
 install(TARGETS
     ${PROJECT_NAME}_chain_piece_node

launch/chain_processor.launch.py

@@ -0,0 +1,20 @@
+import launch
+import launch_ros
+
+_PKG_NAME = 'image_proc_chain'
+
+
+def generate_launch_description():
+    chain_num = launch.substitutions.LaunchConfiguration('chain_num')
+
+    return launch.LaunchDescription([
+        launch.actions.DeclareLaunchArgument(
+            'chain_num',
+            default_value='3',
+            description='Number of image processor(chain_piece)'),
+        launch_ros.actions.Node(
+            package=_PKG_NAME,
+            node_executable=_PKG_NAME+'_chain_processor_node',
+            node_name='chain_processor',
+            output='screen',
+            parameters=[{'chain_num': chain_num}])])

package.xml

@@ -22,6 +22,7 @@
   <depend>sensor_msgs</depend>
   <depend>std_msgs</depend>
 
+  <exec_depend>launch_ros</exec_depend>
   <exec_depend>rosidl_default_runtime</exec_depend>
 
   <member_of_group>rosidl_interface_packages</member_of_group>