[Draft REP 0156:2026] `ros2log` Command Line Interface - Call for Discussion

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Hello ROS community! :waving_hand:

Following the REP-0001:2025 process, I’m opening this discussion thread for Draft REP 0156:2026: ROS Log Command Line Interface.

We are seeking community feedback on this REP, so please feel free to share your thoughts and opinion here.

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Abstract

This REP proposes a new ros2log command-line package for ROS that provides a unified, user-friendly interface for runtime logging configuration and inspection.

Motivation

Currently, logging configuration from the command line in ROS 2 is limited or inconsistent. There is no central dedicated CLI for logging operations, which leads to:

  • Scattered approaches (ad-hoc subcommands or raw service calls)
  • Error-prone workflows requiring manual service calls
  • Poor discoverability for logging-related features

As ROS 2 logging is crucial for debugging and production diagnostics, users need a clear and ergonomic CLI to interact with it.

Proposed Functionality

The REP proposes introducing a new ros2 log CLI command group with the following subcommands:

Subcommand Description
ros2 log list List nodes that support runtime log configuration
ros2 log levels Show all valid log level values (DEBUG, INFO, WARN, ERROR, FATAL)
ros2 log get <node> Retrieve the current log level of a node
ros2 log set <node> <level> Set the log level of a node
ros2 log watch Tail/monitor logs from nodes via rosout
ros2 log describe <node> Display metadata (available loggers, effective levels)

Previous Discussions

This proposal builds on previous community discussions:

Looking forward to your feedback! :rocket:

This discussion thread follows REP-0001:2025 Step 4. Substantial discussion should happen in this public topic to ensure all interested people can participate.

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2

Thanks for opening the REP. I think it will help developers to better utilize logging during development and analyzing of systems.

I just have the following remarks:

  • Would it be beneficial to have an environment variable to globally set enable_logger_service for all nodes, so that it’s easier to benefit from the new feature without editing all launch files?
  • For ros2 log watch it would be nice to have a --format arg which allows to customize the output or even an json option.
  • The only major feature which is still missing is to view/filter all log msgs from the current or previous run similar to what journalctl provides. (As I understand it, the watch command only shows msgs which are received after the command is executed.)
    Currently it is easy to miss a warning or error in the output on the console, especially if multiple nodes output to the same console. A nice way to filter for specific msgs would be a game changer. But maybe this feature should/could be a new REP after this one is completed :wink: