Nextcloud, Gitlab (Docker) are offline, no DNS resolution, wrong entry and no LDAP in Nextcloud, please help

Hello all,

i use here UCS on the latest patchlevel 4.4-5 errata725.

Nextcloud is on Version 18.0.7-0. But i think it es an more UCS generic problem, because the other docker GitLAB is also infected. The Server is an Slave. So what i have observed:

  • UCS Selfcheck is ok
  • Name resolution in UCS is also ok
  • Name resolution in both dockers not working
root@nextc-33480814:/# ping google.com
ping: google.com: Temporary failure in name resolution

But IP ping is normal:

root@nextc-33480814:/# ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=114 time=32.1 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=114 time=30.6 ms

IPV6 is not available in the docker, for whatever reason.

The /etc/resolv.conf look likes this:

# Warning: This file is auto-generated and might be overwritten by
#          univention-config-registry.
#          Please edit the following file(s) instead:
# Warnung: Diese Datei wurde automatisch generiert und kann durch
#          univention-config-registry ueberschrieben werden.
#          Bitte bearbeiten Sie an Stelle dessen die folgende(n) Datei(en):
# 
#       /etc/univention/templates/files/etc/resolv.conf
# 

domain  osit.cc
options timeout:2


nameserver 8.8.8.8
nameserver 8.8.4.4

I thought the domains DNS had to go there. But the Google DNS are also entered in all other Docker containers. I searched everything with grep and the UCR, but I can’t find a source where Docker gets these addresses.

Error Messages in the Nextcloudlog are:

Unable to start TLS: Can't contact LDAP server at /var/www/html/apps/user_ldap/lib/LDAP.php#335","userAgent":"Mozilla/5.0 (Linux) mirall/2.6.2-1build1 (Nextcloud)","version":"18.0.7.1"}

"/nextcloud/remote.php/dav/files/susi/","message":{"Exception":"Sabre\\DAV\\Exception\\ServiceUnavailable","Message":"OC\\ServerNotAvailableException: Lost connection to LDAP server.","Code":0,"Trace":[{"file":"/var/www/html/3rdparty/sabre/dav/lib/DAV/Auth/Plugin.php","line":201,"function":"check","class":"OCA\\DAV\\Connector\\Sabre\\Auth","type":"->","args"

Is this message in the Log, i have no response in the Webinterface. For a workaround (that seems to be working) i have set the localhost FQDN with IP address in the hostsfile of the docker.
Also the Webcheck of nextcloud says that the server did not have any internet access.

This server does not have a working internet connection: Several destinations could not be reached. This means that some functions, such as mounting external storage, notifications about updates or installing third-party apps, will not work. Accessing remote files and sending email notifications will likely not work either. In order to be able to use all functions, establish an internet connection for this server.

Nameresolution on the gitlab Docker on the same server works normal. But… in nextcloud hang, gitlab hangs too, and i get an error 500.

Can any one help me?

The problem was on the HW Firewall, that has really a lot of DNS request to the internet. Strange thing that this also bring GIT and Nextcloud after some time down. After we reconfigure the firewall everything works normal.