Raspberry Pi Cluster - Fixing DNS Resolv on Master

I had setup a raspberry pi cluster, and suddenly the master became non-operational. The cluster was able to see itself, but if I login to master node, I noticed it was not able communicate externally.

The DNS Resolution for any site from master was failing.

Then I figured that Ubuntu had made some changes to resolve.conf protocol

Ubuntu requested users not to edit /etc/resolv.conf, and it's content on my cluster was not something that I wanted.

I had setup pihole, and my devices had started to see the internet through this. I noticed that Ubuntu since 18.04 had not set my router as the first nameserver and thus after pi-hole experiment, my master node lost its resolution capability

Fixing the Ubuntu DNS resolution was easy. I followed this post from datawookie

1. resolvconf package was already installed.

2. Edit /etc/resolvconf/resolv.conf.d/head

nameserver <pi-hole-server>
nameserver 8.8.4.4
nameserver 8.8.8.8

3. Restart the resolvconf server

sudo service resolvconf restart