> OK. I was just trying to point out that there needs to be about 1-2 day > period (releng knows best) between the 0 day push and the actual > announcement. Maybe that's why we usually have 4 days between Go and the > announcement? I don't know whether there's a releng process for it or not, > but since QA wants to track 0 day updates more reliably, it would make sense > to also have a similar process in releng space to ensure the updates are > ready for everyone when the announcement goes out. I'd like to avoid the > system-upgrade sad story next time.
I've tried to find out some of the technical details of this. Mirrormanager publishes the current hash of repomd.xml, and also hashes of usually up to two older repomd.xml files. You can see it here: https://mirrors.fedoraproject.org/metalink?repo=rawhide&arch=x86_64 It's the <hash> tag in <file> and <alternates> tags. Here's a nice graph showing how often our mirrors distribute current, or older content: https://adrian.fedorapeople.org/f22-updates-repomd-propagation.svg The time restraints are defined here: https://github.com/fedora-infra/mirrormanager2/blob/master/mirrormanager2/lib/model.py#L314 If the current push is older than 2 days, there should be no alternate hashes older than 3 days. If the current push is younger, there can be one hash arbitrarily old, but no further hashes older than 3 days. I hope I read the code correctly (the docstring doesn't seem to match it exactly). However, it also depends on how often metalink is regenerated, the old items will not disappear on their own. I learned that all metalinks are regenerated based on any of these fedmsg events: org.fedoraproject.prod.bodhi.updates.fedora.sync org.fedoraproject.prod.compose.rawhide.rsync.complete org.fedoraproject.prod.compose.branched.rsync.complete So if there is no new push (in any repository), metalinks are not regenerated and old hashes are not dropped. Theoretically releng could send out one of those fedmsg events artificially to trigger metalink regeneration, if needed. Currently, there are no means to generate a new metalink with alternative hashes disabled, or removing those alternatives from the metalink intentionally at some point of time afterwards. That would require patching our tools. This would of course lead to a larger load on our master mirror and those mirrors which managed to get synced quickly, because that would disqualify any other mirrors which are not completely current. But it could get handy in some situations, unfortunately the tools do not allow it at the moment. The second part of the story is dnf. In dnf, metadata_expire= option defines how often metalink is pulled again and new metadata are downloaded if the cached metadata hash differs from the current hash in the metalink. However, if the top-listed repository is not completely up-to-date (it contains current-1 or current-2 metadata), but its hash is listed among alternate hashes in the metalink, dnf is fine with that and does not attempt to query different repos to retrieve the very current metadata. That means that as long as the metalink contains some older hashes, and some repository offers that older metadata, some users might not get latest metadata. The default value for metadata_expire is 6 hours for stable updates. So, the outcome of this exercise is: If we want to be sure the latest updates are available to _all_ our users, we need to wait until there are no older metadata hashes in the metalink and then 6 more hours. There will be no older metadata hashes in the metalink when 3 days pass since the push of the important update, *once* there is a new push after that time (which will regenerate the metalink), or if releng send out a fake event manually. This is, uh, a) quite a long time and b) complex. I'll be very glad if you can point out anything that I've described or understood wrong. -- test mailing list test@lists.fedoraproject.org To unsubscribe: http://lists.fedoraproject.org/admin/lists/test@lists.fedoraproject.org
