Dns

The DNS configuration is a critical aspect of our setup. To enable name resolution in our virtualized environment, follow these steps:

1. Create the primary DNS configuration file for the dnsmasq server:

2. /opt/dnsmasq/dnsmasq.conf

   strict-order
   bind-dynamic
   #log-queries
   bogus-priv
   dhcp-authoritative
   
   # BM Network IPv4
   dhcp-range=dual,192.168.126.120,192.168.126.250,255.255.255.0,24h
   dhcp-option=dual,option:dns-server,192.168.126.1
   dhcp-option=dual,option:router,192.168.126.1
   
   # BM Network dual
   dhcp-range=dual,2620:52:0:1306::11,2620:52:0:1306::20,64
   dhcp-option=dual,option6:dns-server,2620:52:0:1306::1
   
   resolv-file=/opt/dnsmasq/upstream-resolv.conf
   except-interface=lo
   dhcp-lease-max=81
   log-dhcp
   no-hosts
   
   # DHCP Reservations
   dhcp-leasefile=/opt/dnsmasq/hosts.leases
   
   # Include all files in a directory depending on the suffix
   conf-dir=/opt/dnsmasq/include.d/*.dual
   

Create the upstream resolver to delegate the non-local environments queries

• /opt/dnsmasq/upstream-resolv.conf

  nameserver 8.8.8.8
  nameserver 8.8.4.4
  

Create the different component DNS configurations

• /opt/dnsmasq/include.d/hosted-nodeport.dual

  host-record=api-int.hosted-dual.hypershiftbm.lab,192.168.126.20
  host-record=api-int.hosted-dual.hypershiftbm.lab,192.168.126.21
  host-record=api-int.hosted-dual.hypershiftbm.lab,192.168.126.22
  host-record=api.hosted-dual.hypershiftbm.lab,192.168.126.20
  host-record=api.hosted-dual.hypershiftbm.lab,192.168.126.21
  host-record=api.hosted-dual.hypershiftbm.lab,192.168.126.22
  
  ## IMPORTANT!: You should point to the node which is exposing the router.
  ## You can also use MetalLB to expose the Apps wildcard.
  address=/apps.hosted-dual.hypershiftbm.lab/192.168.126.30
  
  dhcp-host=aa:aa:aa:aa:04:11,hosted-worker0,192.168.126.30
  dhcp-host=aa:aa:aa:aa:04:12,hosted-worker1,192.168.126.31
  dhcp-host=aa:aa:aa:aa:04:13,hosted-worker2,192.168.126.32
  dhcp-host=aa:aa:aa:aa:11:01,hosted-worker0,[2620:52:0:1306::30]
  dhcp-host=aa:aa:aa:aa:11:02,hosted-worker1,[2620:52:0:1306::31]
  dhcp-host=aa:aa:aa:aa:11:03,hosted-worker2,[2620:52:0:1306::32]
  

• /opt/dnsmasq/include.d/hub.dual

  host-record=api-int.hub-dual.hypershiftbm.lab,192.168.126.10
  host-record=api.hub-dual.hypershiftbm.lab,192.168.126.10
  address=/apps.hub-dual.hypershiftbm.lab/192.168.126.11
  dhcp-host=aa:aa:aa:aa:10:01,ocp-master-0,192.168.126.20
  dhcp-host=aa:aa:aa:aa:10:02,ocp-master-1,192.168.126.21
  dhcp-host=aa:aa:aa:aa:10:03,ocp-master-2,192.168.126.22
  dhcp-host=aa:aa:aa:aa:10:06,ocp-installer,192.168.126.25
  dhcp-host=aa:aa:aa:aa:10:07,ocp-bootstrap,192.168.126.26
  
  host-record=api-int.hub-dual.hypershiftbm.lab,2620:52:0:1306::2
  host-record=api.hub-dual.hypershiftbm.lab,2620:52:0:1306::2
  address=/apps.hub-dual.hypershiftbm.lab/2620:52:0:1306::3
  dhcp-host=aa:aa:aa:aa:10:01,ocp-master-0,[2620:52:0:1306::5]
  dhcp-host=aa:aa:aa:aa:10:02,ocp-master-1,[2620:52:0:1306::6]
  dhcp-host=aa:aa:aa:aa:10:03,ocp-master-2,[2620:52:0:1306::7]
  dhcp-host=aa:aa:aa:aa:10:06,ocp-installer,[2620:52:0:1306::8]
  dhcp-host=aa:aa:aa:aa:10:07,ocp-bootstrap,[2620:52:0:1306::9]
  

• /opt/dnsmasq/include.d/infra.dual

  host-record=registry.hypershiftbm.lab,2620:52:0:1306::1
  host-record=registry.hypershiftbm.lab,192.168.126.1
  

To proceed, we must create a systemd service for the management of the dnsmasq service and disable the system's default dnsmasq service:

• /etc/systemd/system/dnsmasq-virt.service

  [Unit]
  Description=DNS server for Openshift 4 Clusters.
  After=network.target
  
  [Service]
  User=root
  Group=root
  ExecStart=/usr/sbin/dnsmasq -k --conf-file=/opt/dnsmasq/dnsmasq.conf
  
  [Install]
  WantedBy=multi-user.target
  

The commands to do so:

systemctl daemon-reload
systemctl disable --now dnsmasq
systemctl enable --now dnsmasq-virt