0020421: Docker bypasses any DNS Servers set in ClearOS and uses OpenDNS

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Date Submitted

Last Update

0020421

ClearOS

app-docker - Docker

public

2018-06-20 01:56

2021-11-11 05:52

Reporter

NickH

Assigned To

Priority

normal

Severity

minor

Reproducibility

always

Status

closed

Resolution

suspended

Platform

OS Version

Product Version

7.4.0 Updates

Target Version

Fixed in Version

Summary

0020421: Docker bypasses any DNS Servers set in ClearOS and uses OpenDNS

Description

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

Issue History
Date Modified	Username	Field	Change
2018-06-20 01:56	NickH	New Issue
2018-06-20 07:39	user2	Status	new => confirmed
2021-11-11 05:47	NickH	Summary	Docker bypasses any DNS Servers set in ClearOS and uses OpenVPN => Docker bypasses any DNS Servers set in ClearOS and uses OpenDNS
2021-11-11 05:52	NickH	Note Added: 0016251
2021-11-11 05:52	NickH	Status	confirmed => closed
2021-11-11 05:52	NickH	Resolution	open => suspended

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