[ZBX-25025] Zabbix Server/Proxy ignores changes in resolv.conf with async dns in 7.0+ Created: 2024 Aug 12  Updated: 2025 Feb 04  Resolved: 2025 Feb 04

Status: Closed
Project: ZABBIX BUGS AND ISSUES
Component/s: Proxy (P), Server (S)
Affects Version/s: 7.0.2, 7.2.0alpha1
Fix Version/s: 7.0.4rc1, 7.2.0alpha1

Type: Problem report Priority: Major
Reporter: Edgar Akhmetshin Assignee: Sergejs Boidenko
Resolution: Fixed Votes: 2
Labels: None
Remaining Estimate: Not Specified
Time Spent: 1h
Original Estimate: Not Specified
Environment:

Any OS/Zabbix server 7.0

Issue Links:
Duplicate
duplicates ZBX-25671 Unable compile with libevent 2.0 Closed
Related
related to ZBX-25748 Can't get the DNS refresh to work pro... Closed
Team: Team B
Sprint: S24-W34/35, S24-W36/37
Story Points: 3

 Description   

Steps to reproduce:

  1. Start using Agent polling (passive checks) with DNS names as a host interface
  2. use some faulty dns settings (not working, not reachable, etc)
  3. fix DNS issues in resolv.conf
  4. check if DNS resolution started to work
  5. will not work until zabbix-server or zabbix-proxy restarted

Result:
Level 3 log will give: 

27041:20240805:101152.822 Zabbix agent item "vfs.fs.size[/nisaba/micvna,used]" on host "x5backup" failed: first network error, wait for 15 seconds
27041:20240805:101152.831 Zabbix agent item "system.cpu.util[,interrupt]" on host "qc" failed: first network error, wait for 15 seconds
27041:20240805:101153.115 Zabbix agent item "system.cpu.util[,iowait]" on host "mic-dicom-router-mercure" failed: first network error, wait for 15 seconds
27041:20240805:101154.826 Zabbix agent item "system.cpu.util[,guest_nice]" on host "pluto" failed: first network error, wait for 15 seconds

Higher log level will give: 

27041:20240809:131016.823 cannot resolve DNS name: nodename nor servname provided, or not known

Expected:
Automatic refresh/renew of the DNS settings, or at least an option to use runtime control, so DNS settings can be refreshed. Also should be documented, if no automatic solution is possible.



 Comments   
Comment by Vladislavs Sokurenko [ 2024 Aug 28 ]

What is the version of libevent library ? It looks like it was not built with getaddrinfo support

<sboidenko> version 2.1.12 built with USE_NATIVE_GETADDRINFO

Comment by Markku Leiniö [ 2024 Aug 28 ]

When I tested and experienced the same (= resolv.conf changes were not applied automatically), I had Debian 12-supplied "libevent-core-2.1-7:amd64" package version "2.1.12-stable-8".

Comment by Sergejs Boidenko [ 2024 Sep 11 ]

Fixed in:

Comment by Artyom Tsybulkin [ 2024 Dec 02 ]

It seems like this issue back. On 7.0.6. AlmaLinux 9.5. Passive agents, when server/proxy configured to use DNS instead of IP, a lot of `failed: first network error, wait for 15 seconds` in log. Any idea?

Comment by Artyom Tsybulkin [ 2025 Jan 14 ]

Scenario: I have WIndows environment with huge set of virtual machines, and all addresses assigning by DHCP. In this case I can't use static IP interfaces for Zabbix agents when I want to use passive agents. The solution to use DNS and A record as Zabbix agent interface.

 

Issue 1: this is only one part of problem - connectivity issues.

Issue 2: Discovery - it's can be very good to perform reverse nslookup requests to convert IP addresses into names and use names finally as interfaces. 

 

Comment by Sergejs Boidenko [ 2025 Feb 04 ]

Fix for ZBX-25748 can solve issue

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