Add `ExecuteProcess` Action to Support External Process Execution in launch_graph visualization

[adharshvenkat]

Hey @ijnek,

Following up on our exchange on LinkedIn about enhancing launch_graph, I’d like to propose moving forward with the ExecuteProcess action. This would be a valuable addition for running arbitrary shell commands or external programs, helping to streamline common ROS 2 workflows.

I’m ready to start working on this feature and would love to align with you on the best approach for integration.

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Motivation

Currently, launch_graph focuses on launching ROS nodes and managing launch descriptions but does not provide a straightforward way to execute arbitrary external processes within the graph. Many practical use cases involve running shell commands, scripts, or auxiliary tools alongside ROS nodes during launch.

Adding a simple ExecuteProcess action would:

• Enable users to include external commands in their launch workflows.
• Allow capturing process outputs and exit codes for basic error handling.
• Facilitate integration of non-ROS tools or scripts without leaving the launch graph context.

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Proposed Implementation

• Introduce a new ExecuteProcess action class (e.g., in launch_graph/process_execute.py) that accepts:
  • command: the executable and its arguments (list or string).
  • Optional parameters such as env (environment variables), cwd (working directory), and capture_output (to capture stdout/stderr).
• Integrate ExecuteProcess nodes into the existing graph framework so they can be added and visualized alongside other actions like Node and GroupAction.
• Update graph traversal and visualization logic to recognize ExecuteProcess nodes, possibly using a distinct shape for clarity.

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Expected Impact

This addition would provide a straightforward and practical way to visualize external processes launched using ExecuteProcess action

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Thanks again for the great project and the opportunity to collaborate! Once we align on the implementation approach, I’ll start working on the feature and submit a PR.

[ijnek]

Just to clarify, launch_graph is a visualization tool for ROS 2 launch files — it doesn't execute actions or manage runtime behavior. From your comment, it sounds like you're describing what ExecuteProcess does in general, rather than suggesting changes to this project specifically.

If you're interested in having launch_graph visualize ExecuteProcess actions in the graph (like it currently does for Node or IncludeLaunchDescription), that would absolutely be in scope — and I’d be happy to support adding that but i see that happening as modifications to the script to support ExecuteProcess action types, and not what you described.

[adharshvenkat]

Thanks for the clarification, @ijnek.

I'm sorry for the ambiguity, my main motivation is to ensure that launch_graph can accurately represent and visualize ExecuteProcess actions, just as it does for Node and IncludeLaunchDescription actions, so users can see the full structure of their launch files, including any external processes invoked. I added the information about the working of ExecuteProcess only to provide the motivation for adding this feature to the existing tool.

With that in mind, I’ll focus my efforts on:

• Extending the parser and visualization logic to recognize and display ExecuteProcess actions within the launch graph
• Ensuring these actions are visually distinct (e.g., with a unique shape or style) for clarity