Error finding preseed file when booting the UbuntuServer installer via iPXE through HTTP

Question

I know the typical settings to run a PXE server is the combination DHCP+TFTP+HTTP/FTP/NFS... servers, but my setting must be only DHCP+HTTP, so my dhcpd.conf has these lines:

subnet 192.168.1.0 netmask 255.255.255.0 {
    range 192.168.1.5 192.168.1.10;
    option subnet-mask 255.255.255.0;
    ...
    filename "http://192.168.1.1/pxelinux.0";
}

I use iPXE (http://www.ipxe.org) -which can get pxelinux.0 from a HTTP server- to boot my clients. They see a pxelinux menu with an option to run Ubuntu installer. Its "APPEND" line is like this:

APPEND url=http://192.168.1.1/mountpointisoubuntu/preseed/ubuntu-server.seed

Everythings seems going well during installation until I get a error message:

The installer failed to process preconfiguration file from http://192.168.1.1/pxelinux.0

I've read in Chapter B.2.5 of the Debian Installation Guide that if dhcpd.conf there is a HTTP url, the installer assumes it is the url of a preseed file.

I thought that appending the "url" preseed parameter this behaviour would be overriden, but it is not! What can I do to tell the installer to forget using the url from dhcpd.conf as a preseed file's url?

Answer 1

I can see two options:

1. Change the APPEND line so that it uses static IP settings instead of going out looking for DHCP. This way it should never see the DHCP filename.

2. Change your DHCP server configuration so that it serves the filename only to requests not from a Debian installer. The example given in the Installation guide can be easily adapted:

   # your normal settings
   if substring (option vendor-class-identifier, 0, 3) != "d-i" {
       filename "http://192.168.1.1/pxelinux.0";
   }