hostname change with static ip overwrites (manual) resolv.conf

[Norbert Pfeiler]

1) on a »Ubuntu 16.04.4 LTS« with static ip configuration in /etc/network/interfaces and manual entries in /etc/resolv.conf
2) network-manager 1.2.6-0ubuntu0.16.04.2 is enabled but doesn’t manage any interfaces and therefore doesn’t start dnsmasq

3) using hostnamectl and updating /etc/hosts doesn’t break dns resolution

4) changing the hostname however triggers NetworkManager to start dnsmasq and overwrite /etc/resolv.conf

Workarounds are chattr’ing /etc/resolv.conf or – in this case – disabling NetworkManager but i think this shouldn’t happen.

cat /etc/NetworkManager/NetworkManager.conf
[main]
plugins=ifupdown,keyfile,ofono
dns=dnsmasq

[ifupdown]
managed=false