Character [-] is not valid as the first character in Graph Resource Name [--ros-args].

[Yuchen966]

Bug report

I want to launch parameter_bridge in a customed launch.py file. The code is like this:

ros1_bridge = Node(
        package='ros1_bridge',
        executable='parameter_bridge',
        output='screen'
    )

But when I launch ros1_bridge, it automatically adds the --ros-args argument, which causes an InvalidNameException when the parameter file is not provided as an argument.

Steps to Reproduce:

1. Create a launch file and use the Node class from launch_ros.actions to launch ros1_bridge without explicitly passing the --ros-args argument.
2. Launch the launch file.

Expected Behavior:
The ros1_bridge should launch without any errors, bridging the specified topics between ROS 1 and ROS 2.

Actual Behavior:
The ros1_bridge fails to launch with the following error:

[parameter_bridge-1] terminate called after throwing an instance of 'ros::InvalidNameException'
[parameter_bridge-1]   what():  Character [-] is not valid as the first character in Graph Resource Name [--ros-args].  Valid characters are a-z, A-Z, / and in some cases ~.
[ERROR] [parameter_bridge-1]: process has died [pid XXXX, exit code -6, cmd 'ros2_ws/install/ros1_bridge/lib/ros1_bridge/parameter_bridge --ros-args']

Workaround:
Use the ExecuteProcess class from the launch.actions module instead of the Node class to launch ros1_bridge. Pass the command and arguments explicitly using the cmd parameter.

ros1_bridge = ExecuteProcess( # 
        cmd=['ros2', 'run', 'ros1_bridge', 'parameter_bridge'],
        output='screen',
    )

Although there is a workaround, I am still wondering if I could launch the node directly using launch_ros.actions.Node.

Thanks for any advice!

• Operating System:
  • Ubuntu 20.04
• Installation type:
  • from source
• Version or commit hash:
  • foxy

[ipa-ych]

Hi Yuchen,
I am encountering the same issue with Ubuntu 22.04 & Humble why trying to launch parameter_bridge from Python launch file. Have you found another solution apart from using ExecuteProcess?