General information about this repository, including legal information, build instructions and known issues/limitations, are given in README.md in the repository root.

The diagnostic_common_diagnostics package

This package provides generic nodes to monitor a Linux host.

Currently only the NTP monitor is ported to ROS2.

Nodes

cpu_monitor.py

The cpu_monitor module allows users to monitor the CPU usage of their system in real-time. It publishes the usage percentage in a diagnostic message.

• Name of the node is “cpu_monitor_” + hostname.
• Uses the following args:
  • warning_percentage: If the CPU usage is > warning_percentage, a WARN status will be publised.
  • window: the maximum length of the used collections.deque for queuing CPU readings.

Published Topics

/diagnostics

diagnostic_msgs/DiagnosticArray The diagnostics information.

Parameters

warning_percentage

(default: 90) warning percentage threshold.

window

(default: 1) Length of CPU readings queue.

ntp_monitor.py

Runs ‘ntpdate’ to check if the system clock is synchronized with the NTP server.

• If the offset is smaller than offset-tolerance, an OK status will be published.
• If the offset is larger than the configured offset-tolerance, a WARN status will be published,
• if it is bigger than error-offset-tolerance, an ERROR status will be published.
• If there was an error running ntpdate, an ERROR status will be published.

Published Topics

/diagnostics

diagnostic_msgs/DiagnosticArray The diagnostics information.

Parameters

ntp_hostname

(default: “pool.ntp.org”) Hostname of NTP server.

offset-tolerance”

(default: 500) Allowed offset from NTP host. Above this is a warning.

error-offset-tolerance

(default: 5000000) If the offset from the NTP host exceeds this value, it is reported as an error instead of warning.

self_offset-tolerance

(default: 500) Offset from self

diag-hostname

Computer name in diagnostics output (ex: ‘c1’)

no-self-test

(default: True) Disable self test.

hd_monitor.py

Runs ‘shutil.disk_usage’ to check if there is enough space left on a given device. With default parameters, the following thresholds are used:

• Above 5% of free space left, an OK status will be published.
• Between 5% and 1%, a WARN status will be published,
• Below 1%, an ERROR status will be published.

Published Topics

/diagnostics

diagnostic_msgs/DiagnosticArray The diagnostics information.

Parameters

path

(default: home directory “~”) Path in which to check remaining space.

free_percent_low

(default: 5%) Warning threshold.

free_percent_crit

(default: 1%) Error threshold.

ram_monitor.py

The ram_monitor module allows users to monitor the RAM usage of their system in real-time. It publishes the usage percentage in a diagnostic message.

• Name of the node is “ram_monitor_” + hostname.
• Uses the following args:
  • warning_percentage: If the RAM usage is > warning_percentage, a WARN status will be published.
  • window: the maximum length of the used collections.deque for queuing RAM readings.

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Changelog for package diagnostic_common_diagnostics

4.4.6 (2025-05-26)

• C++17 and cmake 3.20 everywhere (#510)
• Contributors: Christian Henkel

4.4.5 (2025-05-26)

4.4.4 (2025-05-12)

4.4.2 (2025-02-10)

• common_diagnostics cleaned hostname string (#405)
  • Hostnames are properly cleaned to only contain alphanumeric characters or underscore.
• Skipping flaky ntp test (#409)
• Add missing rclpy dependency to common_diagnostics to fix rosdoc2 output (#402)
• Contributors: Christian Henkel, R Kent James, sjusner

4.3.1 (2024-07-30)

• fixing pep257 problems introduced by #334 (#384)
• Port hd_monitor to ROS2 (#334)
• Contributors: Antoine Lima, Christian Henkel

3.2.1 (2024-06-27)

• refactor(sensors_monitor): ros2 port #339
• refactor(ram_monitor): ros2 port (#338)
• NTP monitor improvements (#342)
• Using ubuntu ntp server in systemtest (#346)
• Fixing ntp launchtest (#330)
• Contributors: Christian Henkel, Rein Appeldoorn, Tony Najjar

3.2.0 (2024-03-22)

• Port cpu_monitor to ROS2 (#326)
• Debugging instability introduced by #317 (#323)
• not testing on foxy any more (#310)
• Iron support (#304)
• Contributors: Christian Henkel, Richard

3.1.2 (2023-03-24)

• replacing ntpdate with ntplib (#289)
• Contributors: Christian Henkel

3.1.1 (2023-03-16)

• Secretly supporting galactic (#295)
• Linting additional package (#268)
• Maintainer update
• Contributors: Austin, Christian Henkel, Ralph Lange

3.1.0 (2023-01-26)

• Adding READMEs to the repo (#270)
• License fixes (#263)
• Fix/cleanup ros1 (#257)
• Port ntp_monitor to ROS2 (#242)
• Contributors: Austin, Christian Henkel, RFRIEDM-Trimble, Ralph Lange

1.9.3 (2018-05-02)

1.9.2 (2017-07-15)

• FIX: add missing dependency
• Contributors: trainman419

1.9.1 (2017-07-15)

• Add queue size parameters on Publishers
• Minor python updates
• Added CPU percentage monitor CPU monitor that outputs the average CPU percentage and a percentage per CPU. The user can specify the warning CPU percentage. When one CPU exceeds this percentage, the

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