[CentOS] NetworkManager and /etc/resolv.conf

[Alice Wonder]

On 11/17/2018 06:43 AM, Alice Wonder wrote:
> CentOS 7.5 image running on linode.
> 
> unbound running on localhost.
> 
> Have to use a cron job once a minute to keep /etc/resolv.conf using the 
> localhost for name resolution - whenever NetworkManager gets restarted 
> (usually only a system boot) it gets over-written.
> 
> It seems every distro has a different way of preventing NetworkManager 
> from replacing that file.
> 
> I found instructions for Fedora that said create 
> /etc/NetworkManager/conf.d/no-dns.conf containing
> 
> [main]
> dns=none
> 
> That doesn't seem to have any effect.
> 
> Poking around, I find a file on boot seems to be created called
> 
> /var/run/NetworkManager/resolv.conf
> 
> It has most of the contents of what ends up in /etc/resolv.conf - except 
> w/o the last line, which just reads rotate in generated /etc/resolv.conf.
> 
> It says it's generated by NetworkManager (both /etc/resolv.conf and the 
> one in /var/run/NetworkManager) but neither are specific enough to 
> indicate what is causing them to be created so I can turn it off.
> 
> Anyone know how to tell NetworkManager to just not create that file?
> 
> Using a cron job to overwrite it once a minute works but there must be a 
> proper way.
> 
> I really wish KISS was a design goal when designing system configuration.
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Just found this -

# cat dhclient-exit-hooks
echo 'options rotate' >> /etc/resolv.conf

That's where the last line in /etc/resolv.conf is coming from.