Create containerized Core DNS server

Run the following commands to make required Directory
a. mkdir -p /home/coredns/
b. cd /home/coredns/
c. vi domain.name.db (and paste the below content)

domain.name.      IN  SOA dns.domain.name. domain.name.in. 2015082541 7200 3600 1209600 3600   
service-name      IN A    10.10.x.x  
service2          IN A    10.110.x.x

d. Create the Core File for dns forwarder

vi /home/coredns/Corefile (and paste the below content)

.:53 {   
    forward . 164.100.3.1  # Gateway IP
    log  
    errors  
}  

domain.name:53 {
    file /root/domain.name.db
    log
    errors
}

2. pull this image and run the following commands:

docker run -d --name coredns -p 53:53/udp --restart=always \        --volume=/home/niccloud/coredns/:/root/ \ 
coredns:1.8.4 -conf /root/Corefile

Run the Following command to find the ip of core DNS server

ip a

For example if ip is 10.10.x.x then Add following lines in netplan files of each client nodes

# This file is generated from information provided by the datasource.  Changes
# to it will not persist across an instance reboot.  To disable cloud-init's
# network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
network:
    ethernets:
        ens3:
            dhcp4: true
            nameservers:
                    addresses:
                    - 10.10.x.x
        ens4:
            dhcp4: true
            optional: true
    version: 2

After that run below commands

netplan generate
netplan apply

Run Following command To check connectivity from each node to DNS server

netcat -uzv <DNS-SERVER-IP> <PORT>

OR

Run the following script to create CORE-DNS Server

#!/bin/bash
##*********CREATE DIRECTORY***********
mkdir -p /home/coredns/
echo "Directory Successfully Created"
cd /home/coredns/
##************************************
echo
"domain.name.        IN  SOA dns.cloud.gov.in. pvtdns.domain.name. 2015082541 7200 3600 1209600 3600   
service-name1      IN A    10.10.x.x  
service2             IN A    10.10.x.x" >/home/coredns/domain.name.db
echo 
".:53 {   
    forward . 164.100.3.1  # GATEWAy IP
    log  
    errors  
}
domain.name:53 {
    file /root/domain.name.db
    log
    errors
} " > /home/coredns/Corefile
echo "Both files domain.name.db and Corefile is  created successfully"
############ STOP Resolved Service If Running####################### 
RESOLVE_SERVICE="systemd-resolve"
if pgrep -x "$RESOLVE_SERVICE" >/dev/null
then
echo "$RESOLVE_SERVICE is running So stopping the resolve service"
systemctl stop systemd-resolved
systemctl disable systemd-resolved
else 
echo "$RESOLVE_SERVICE is not running so Start Docker."
fi
############*************************#########################

docker run -d --name coredns -p 53:53/udp --restart=always --volume=/home/coredns/:/root/ coredns:1.8.4 -conf /root/Corefile
docker ps | grep coredns
############***************************************

Git repo For Script

GitHub - vineetkumar03/containerized-coredns-server: containerized-coredns-server

Enjoy!!!