bifrost/doc/source/user/dhcp.rst

Configuring the integrated DHCP 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.

Extending dnsmasq configuration

Bifrost manages the dnsmasq configuration file in /etc/dnsmasq.conf. It is not recommended to make manual modifications to this file after it has been written. dnsmasq supports the use of additional configuration files in /etc/dnsmasq.d, allowing extension of the dnsmasq configuration provided by bifrost. It is possible to use this mechanism provide additional DHCP options to systems managed by ironic, or even to create a DHCP boot environment for systems not managed by ironic. For example, create a file /etc/dnsmasq.d/example.conf with the following contents:

dhcp-match=set:<tag>,<match criteria>
dhcp-boot=tag:<tag>,<boot options>

The tag, match critera and boot options should be modified for your environment. Here we use dnsmasq tags to match against hosts that we want to manage. dnsmasq will use the last matching tagged dhcp-boot option for a host or an untagged default dhcp-boot option if there were no matches. These options will be inserted at the conf-dir=/etc/dnsmasq.d line of the dnsmasq configuration file. Once configured, send the HUP signal to dnsmasq, which will cause it to reread its configuration:

killall -HUP dnsmasq

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,http://<Bifrost Host IP Address>:8080/boot.ipxe
dhcp-boot=/undionly.kpxe,<TFTP Server Hostname>,<TFTP Server IP Address>

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  |
+-------------+       +-----------+