Werk #18277: Agent controller communication

Component

Checks & agents

Title

Agent controller communication

Date

Jul 31, 2025

Level

Trivial Change

Class

Bug Fix

Compatibility

Compatible - no manual interaction needed

Checkmk versions & editions

2.5.0b1 Not yet released	Checkmk Raw (CRE), Checkmk Enterprise (CEE), Checkmk Cloud (CCE), Checkmk MSP (CME)
2.4.0p10	Checkmk Raw (CRE), Checkmk Enterprise (CEE), Checkmk Cloud (CCE), Checkmk MSP (CME)

In some rare cases, the communication between agent controller and agent receiver could fail with an error message Request failed with code 500 Internal Server Error: Internal Server Error.

The agent receiver communicates with the local OMD site via REST-API to fulfill certain requests from the agent controller, and uses localhost as address for the queries.

If localhost is not configured on the Checkmk server (no entry in /etc/hosts), these queries failed, leading to the observed behavior.

The agent receiver now communicates with the local REST-API via the local apache's address that's configured by omd config.

To the list of all Werks