2.2. Configuring the public subnet

Procedure

1. Install dnsmasq:

   $ sudo dnf install dnsmasq

2. Open the dnsmasq configuration file:

   $ sudo vi /etc/dnsmasq.conf

3. Add the following configuration to the dnsmasq configuration file:

   interface=baremetal
   except-interface=lo
   bind-dynamic
   log-dhcp
   
   dhcp-range=<ip_addr>,<ip_addr>,<pub_cidr> 

   1

   
   dhcp-option=baremetal,121,0.0.0.0/0,<pub_gateway>,<prvn_priv_ip>,<prvn_pub_ip> 

   2

   
   
   dhcp-hostsfile=/var/lib/dnsmasq/dnsmasq.hostsfile

   1

   Set the DHCP range. Replace both instances of <ip_addr> with one unused IP address from the public subnet so that the dhcp-range for the baremetal network begins and ends with the same the IP address. Replace <pub_cidr> with the CIDR of the public subnet.

   2

   Set the DHCP option. Replace <pub_gateway> with the IP address of the gateway for the baremetal network. Replace <prvn_priv_ip> with the IP address of the provisioner node’s private IP address on the provisioning network. Replace <prvn_pub_ip> with the IP address of the provisioner node’s public IP address on the baremetal network.

   To retrieve the value for <pub_cidr>, execute:

   $ ibmcloud sl subnet detail <publicsubnetid> --output JSON | jq .cidr

   Replace <publicsubnetid> with the ID of the public subnet.

   To retrieve the value for <pub_gateway>, execute:

   $ ibmcloud sl subnet detail <publicsubnetid> --output JSON | jq .gateway -r

   Replace <publicsubnetid> with the ID of the public subnet.

   To retrieve the value for <prvn_priv_ip>, execute:

   $ ibmcloud  sl hardware detail <id> --output JSON | \
               jq .primaryBackendIpAddress -r

   Replace <id> with the ID of the provisioner node.

   To retrieve the value for <prvn_pub_ip>, execute:

   $ ibmcloud sl hardware detail <id> --output JSON | jq .primaryIpAddress -r

   Replace <id> with the ID of the provisioner node.

4. Obtain the list of hardware for the cluster:

   $ ibmcloud sl hardware list

5. Obtain the MAC addresses and IP addresses for each node:

   $ ibmcloud sl hardware detail <id> --output JSON | \
     jq '.networkComponents[] | \
     "\(.primaryIpAddress) \(.macAddress)"' | grep -v null

   Replace <id> with the ID of the node.

   Example output

   "10.196.130.144 00:e0:ed:6a:ca:b4"
   "141.125.65.215 00:e0:ed:6a:ca:b5"

   Make a note of the MAC address and IP address of the public network. Make a separate note of the MAC address of the private network, which you will use later in the install-config.yaml file. Repeat this procedure for each node until you have all the public MAC and IP addresses for the public baremetal network, and the MAC addresses of the private provisioning network.

6. Add the MAC and IP address pair of the public baremetal network for each node into the dnsmasq.hostsfile file:

   $ sudo vim /var/lib/dnsmasq/dnsmasq.hostsfile

   Example input

   00:e0:ed:6a:ca:b5,141.125.65.215,master-0
   <mac>,<ip>,master-1
   <mac>,<ip>,master-2
   <mac>,<ip>,worker-0
   <mac>,<ip>,worker-1
   ...

   Replace <mac>,<ip> with the public MAC address and public IP address of the corresponding node name.

7. Start dnsmasq:

   $ sudo systemctl start dnsmasq

8. Enable dnsmasq so that it starts when booting the node:

   $ sudo systemctl enable dnsmasq

9. Verify dnsmasq is running:

   $ sudo systemctl status dnsmasq

   Example output

   ● dnsmasq.service - DNS caching server.
   Loaded: loaded (/usr/lib/systemd/system/dnsmasq.service; enabled; vendor preset: disabled)
   Active: active (running) since Tue 2021-10-05 05:04:14 CDT; 49s ago
   Main PID: 3101 (dnsmasq)
   Tasks: 1 (limit: 204038)
   Memory: 732.0K
   CGroup: /system.slice/dnsmasq.service
   └─3101 /usr/sbin/dnsmasq -k

10. Open ports 53 and 67 with UDP protocol:

    $ sudo firewall-cmd --add-port 53/udp --permanent

    $ sudo firewall-cmd --add-port 67/udp --permanent

11. Add provisioning to the external zone with masquerade:

    $ sudo firewall-cmd --change-zone=provisioning --zone=external --permanent

    This step ensures network address translation for IPMI calls to the management subnet.

12. Reload the firewalld configuration:

    $ sudo firewall-cmd --reload