LinuxExam.net: DNS not working inside docker containers on CentOS 8

ISSUES

Till today (Sep 30, 2020), docker is still NOT officially supported on CentOS 8 due to the conflicts between Docker.com and RedHat.

When installed on CentOS 8, docker containers run into DNS issues right away.

There're two ways to solve this for now.

Change firewalld's backend from nftables to iptables

# cat /etc/firewalld/firewall.conf | grep Backend

FirewallBackend=iptables

# systemctl restart firewalld

Add SNAT to the public zone.

# firewall-cmd --zone=public --add-masquerade --permanent

# firewall-cmd --reload

# firewall-cmd --list-all

public (active)

  target: default

  icmp-block-inversion: no

  interfaces: enp0s25

  sources:

  services: cockpit dhcpv6-client http smtp ssh

  ports: 8888/udp 8000/tcp 8087/tcp

  protocols:

  masquerade: yes

  forward-ports:

  source-ports:

  icmp-blocks:

  rich rules:

https://github.com/docker/for-linux/issues/957