ClearFoundation Tracker - ClearOS
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0020421ClearOSapp-docker - Dockerpublic2018-06-20 01:562021-11-11 05:52
NickH 
 
normalminoralways
closedsuspended 
7.4.0 Updates 
 
0020421: Docker bypasses any DNS Servers set in ClearOS and uses OpenDNS
When docker loads, to define its DNS servers it attempts to read /etc/resolv.conf then discounts loopback. As it finds nothing there it falls back to using OpenDNS and generated the following line in the logs:

Jun 14 18:45:58 server dockerd-current: time="2018-06-14T18:45:58.083955517+01:00" level=info msg="No non-localhost DNS nameservers are left in resolv.conf. Using default external servers: [nameserver 8.8.8.8 nameserver 8.8.4.4]"
Jun 1

Set like this, it is impossible for docker to resolve hostnames of local devices. In ClearGLASS in an environment of mixed cloud and local servers, you would be able to address the cloud servers by FQDN but the local ones would have to be addressed by IP.

The solution is to add a line to /etc/docker/daemon.json between the braces:

"dns": ["172.18.0.1"]

This can be programatically maintained to track the docker0 LAN interface.
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Issue History
2018-06-20 01:56NickHNew Issue
2018-06-20 07:39user2Statusnew => confirmed
2021-11-11 05:47NickHSummaryDocker bypasses any DNS Servers set in ClearOS and uses OpenVPN => Docker bypasses any DNS Servers set in ClearOS and uses OpenDNS
2021-11-11 05:52NickHNote Added: 0016251
2021-11-11 05:52NickHStatusconfirmed => closed
2021-11-11 05:52NickHResolutionopen => suspended

Notes
(0016251)
NickH   
2021-11-11 05:52   
Migrated to https://gitlab.com/clearos/clearfoundation/app-docker/-/issues/3 [^]