Using Bifrost with your own DHCP server

The possibility exists that a user may already have a Dynamic Host Configuration Protocol (DHCP) server on their network.

Currently Ironic, when configured with Bifrost in standalone mode, does not utilize a DHCP provider. This would require a manual configuration of the DHCP server to deploy an image. Bifrost utilizes dnsmasq for this functionality; however, any DHCP server can be utilized. This is largely intended to function in the context of a single flat network although conceivably the nodes can be segregated.

What is required:

• DHCP server on the network segment
• Appropriate permissions to change DHCP settings
• Network access to the API and conductor. Keep in mind the iPXE image does not support ICMP redirects.

Example DHCP server configurations

In the examples below port 8080 is used. However, the port number may vary depending on the environment configuration.

dnsmasq:

dhcp-match=set:ipxe,175 # iPXE sends a 175 option.
dhcp-boot=tag:!ipxe,/undionly.kpxe,<TFTP Server Hostname>,<TFTP Server IP Address>
dhcp-boot=http://<Bifrost Host IP Address>:8080/boot.ipxe

Internet Systems Consortium DHCPd:

if exists user-class and option user-class = "iPXE" {
      filename "http://<Bifrost Host IP Address>:8080/boot.ipxe";
} else {
      filename "/undionly.kpxe";
      next-server <TFTP Server IP Address>;
}

Architecture

It should be emphasized that Ironic in standalone mode is intended to be used only in a trusted environment.

         +-------------+
         | DHCP Server |
         +-------------+
                |
+--------Trusted-Network----------+
       |                    |
+-------------+       +-----------+
|Ironic Server|       |   Server  |
+-------------+       +-----------+

Setting static DHCP assignments with the integrated DHCP server

You can set up a static DHCP reservation using the ipv4_address parameter and setting the inventory_dhcp setting to a value of true. This will result in the first MAC address defined in the list of hardware MAC addresses to receive a static address assignment in dnsmasq.

Forcing DNS to resolve to ipv4_address

dnsmasq will resolve all entries to the IP assigned to each server in the leases file. However, this IP will not always be the desired one, if you are working with multiple networks. To force DNS to always resolve to ipv4_address please set the inventory_dns setting to a value of true. This will result in each server to resolve to ipv4_address by explicitly using address capabilities of dnsmasq.