The document root for derived.archive.canonical.com points to an
"archives" subdirectory that includes only some carefully-constructed
symlinks that point into sub-sub-directories of `archives_dir`: for
example, `archives/ubuntu-rtm` is a symlink to
`ubuntu-rtm-archive/ubuntu-rtm` (relative to `archives_dir`), which lets
us expose the actual archive contents without exposing all the temporary
data and so on under other subdirectories of `ubuntu-rtm-archive`.
This is all quite historically weird, but let's mimic it so that we can
migrate from the pre-charmed deployment while preserving existing URLs.
Cope more gracefully with intermittent builder glitches
buildd-manager would previously immediately count any single scan
failure against the builder and job. This meant that three glitches --
say, network timeouts -- over the course of job would result in the
build being requeued. A builder's failure count is reset on successful
dispatch, but a job's deliberately isn't since we want to fail builds
that are repeatedly killing builders. This meant that a single network
glitch in the second attempt at a build would cause it to be failed.
This added layer of failure counting substantially reduces the
likelihood of those two scenarios, by requiring five consecutive
unsuccessful scans before a single failure is counted against a builder
or job. This means that brief network interruptions, or indeed temporary
insanity on buildd-manager's part, should no longer cause builds to be
requeued or failed at all.
The only significant downside of this change is that recovery from
legitimate failures will now take a few minutes longer. But that's much
less of a concern with the very large build farm we have nowadays.
