Cobbler does this using anamon, a script which is fetched and executed in kickstart %pre. It watches various anaconda logs and reports them back to Cobbler. We should do a similar thing in Beaker, by taking the anamon script and modifying it to submit the logs to Beaker instead.
I think we should take this opportunity to improve the anamon script, currently every time a watched file grows it re-sends the file from the beginning. It should keep track of the offset and only transfer the delta.
We should also submit logs by recipe ID (or task or provision ID, or whatever), instead of by system name.
This patch is anamon copied mostly as is: http://gerrit.beaker-project.org/1029 The main difference is that it uses the recipe id instead of hostname, as per comment 2. I haven't tackled Bill's suggestion in comment 1 to make the log uploads smarter.
Beaker 0.9.0 has been released.