rcl_logging_syslog 🚢🚀🚂

rcl_logging_syslog is alternative logging backend implementation that can be used for ROS 2 application via rcl_logging_interface.

rcl_logging_syslog uses SYSLOG(3) to send the log data to rsyslog a.k.a rocket-fast system for log processing 🚀.

The main objective is that Enabling ROS 2 logging system with Cloud-Native Log Management and Observability.

see overview slide deck for more information.

Motivation

The logging data is critical especially for entire system observability and status, so that application can alert the administrator or even give the feedback to the system with adjusting the parameter. This importance rises once it comes to robotics and robot application, especially distributed system such as ROS 2 or edge computing because we must be able to specify what went wrong in the 1st place with these logging data.

rsyslog is available in default Ubuntu distribution managed by system service, performative, and many configuration supported including log data pipeline. So that user can choose the logging configuration depending on the application requirement and use case, sometimes file system sink, sometimes forwarding to remote rsyslogd, or even FluentBit.

FluentBit is a Fast Log Processor and Forwarder part of Graduated Fluentd Ecosystem and a CNCF sub-project.

Demonstration

See how it works 🔥

• rsyslog / FluebtBit

https://github.com/user-attachments/assets/bdb05bf7-92b2-4b9a-8f20-3d3b803a7a86

• rsyslog / Fluentd / Loki / Grafana

https://github.com/user-attachments/assets/4a1aae42-5c55-4f31-9198-8c7c246244ca

Tutorials

• How to integrate with Fluentd / Loki / Grafana

Supported ROS Distribution

rcl_logging_implementation

Starting with Rolling Ridley, ROS 2 introduces rcl_logging_implementation, a package that enables runtime dynamic loading of logging backends, similar to how rmw_implementation works for middleware selection. This abstraction layer allows users to switch between different logging implementations (such as rcl_logging_spdlog, rcl_logging_noop, or rcl_logging_syslog) without rebuilding RCL or application code.

See the ROS 2 Logging Documentation for more details.

Runtime Dynamic Loading vs Static Linking

The logging system supports two build configurations:

Dynamic Loading (Default, Rolling or later)

By default, rcl links against rcl_logging_implementation, which dynamically loads the logging backend at runtime. This approach provides maximum flexibility, allowing the logging implementation to be changed via the RCL_LOGGING_IMPLEMENTATION environment variable without recompilation.

• The logging implementation is loaded as a shared library at runtime.
• No rebuild of rcl is required to switch between logging implementations.
• Simply build rcl_logging_syslog and set the environment variable to use it.

Static Linking (Kilted or older distributions)

For Kilted, Jazzy, and Humble distributions, the rcl_logging_implementation package is not available. Users must rebuild rcl with the RCL_LOGGING_IMPLEMENTATION CMake/environment variable set at build time to statically link rcl_logging_syslog.

• The specified implementation is statically linked into rcl at build time.
• Runtime switching is NOT available.
• Requires rebuilding rcl whenever you want to change the logging backend.

Installation

Prerequisites

• rsyslog installation

rcl_logging_syslog requires rsyslog package, which Ubuntu should have already in default. But if you are using container, the situation is bit different from host system since there is no system services or rsyslogd is running by default. In the case of container, we need to install rsyslog packages in the container root file system.

[!NOTE] We can enable the container with host system privileges but that is NOT recommended, especially for security.

### Install rsyslog package
apt install rsyslog

• create ros directory for rsyslog.

The following commands require root permission.

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