TFTP automatic boot file download does not track updates
My colleague and I ran into a bug in the Ubuntu 12.04.4 netboot kernel. A fix is available in a newer version, but the Smart-proxy does not check for changes in the boot files if they already exist in the tftp directory.
A workaround for most systems is to delete the local files from the TFTP directory before a build, allowing the Smart-proxy to download the new files. On Debian-based systems this does not work, though. The problem there is that
Operatingsystem::Debian#boot_files_uri builds the download URI based on the release name, but most distros place fixes and updates in codename-updates and/or codename-security. Changing the release name to something like codename-updates causes other URIs to fail, so the workaround for Debian-based operating systems is to delete the local files and replace them with current files by hand.
Due to a lack of reliable metadata, staying up-to-date is probably not entirely feasible. The files could be downloaded at an interval, like every 5th build or the first build of each week. Cron scripts could also be generated, or just suggested in the documentation.
Debian systems might also be brought into parity with others via a custom URI option or some exception logic (once #3034 is resolved).