Sensors Disapearing after discovery-wrapper.py cronjob

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1

Hello,

I’ve noticed sensors disappearing after discovery-wrapper.py runs via cron. I believe other default cron jobs cause them to disappear as well, but I have not gone through and disabled each in cron and run them manually, certainly can if it is warranted. I can recreate by running discovery-wrapper.py manually every time.

Of course, can run the “lnms device:discover -m sensors”, it rediscovers them every time, but obviously loses visibility while they are not known within LibreNMS.

Is there a way to stop this behavior short of disabling the cron jobs and periodically running them manually, then do the discover sensors step above?

It is the “dockerized” version of librenms if that makes any difference.

#######################################################################################################################################################################################################################################

===========================================

Component Version
LibreNMS 26.5.1 (2026-05-21T02:11:11-05:00)
DB Schema 2026_05_06_145721_regenerate_devices_table_display_field (386)
PHP 8.4.21
Python 3.12.13
Database MariaDB 10.11.18-MariaDB-ubu2204
RRDTool 1.9.0
SNMP 5.9.5.2
===========================================

[OK] Installed from package; no Composer required
[OK] Database Connected
[OK] Database Schema is current
[OK] SQL Server meets minimum requirements
[OK] lower_case_table_names is enabled
[OK] MySQL engine is optimal
[OK] Database and column collations are correct
[OK] Database schema correct
[OK] MySQL and PHP time match
[OK] Active pollers found
[OK] Dispatcher Service is enabled
[OK] Locks are functional
[OK] No active python wrapper pollers found
[OK] Redis is functional
[OK] rrd_dir is writable
[OK] rrdtool version ok
[WARN] Non-git install, updates are manual or from package

Thank you.

2

NOTE:

It did it on the prior version as well:

===========================================

Component Version
LibreNMS 26.4.1 (2026-04-22T17:20:03-05:00)
DB Schema 2026_04_02_141445_add_ssl_certificate_update_permission (383)
PHP 8.3.29
Python 3.12.13
Database MariaDB 10.11.16-MariaDB-ubu2204
RRDTool 1.9.0
SNMP 5.9.4
===========================================
3

That’s not a common issue, especially if it happens every time discovery runs.

However without the full discovery debug output, no one can really help

4

There’s a problem with your statements. The docker containers never run discovery-wrapper.py.

The output of the discovery runs that remove the sensors would be helpful.

5

I assumed it ran as its in a contab @ /opt/librenms/dist/librenms.cron

eg.
33 */6 * * * librenms /opt/librenms/cronic /opt/librenms/discovery-wrapper.py 1

6

No, the docker containers use the dispatcher service and don’t have a cron service afaik.