CDN issue causing 00-index.tar to be out of sync with available tarballs #537
Description
I've experienced this personally in running the all-cabal-hashes mirror, and have received user reports. Relevant links:
- https://twitter.com/snoyberg/status/773847008721395712
- yaml-0.8.18.6: Package not found: No such package version for yaml snoyberg/yaml#97
The idea is: you download the 00-index.tar.gz file from Hackage (e.g., via cabal update), and it includes a .cabal file for a certain package/version combo (like yaml-0.8.18.6.cabal). But when you try to download yaml-0.8.18.6.tar.gz from Hackage, you get a 404 for a while, which eventually corrects itself. I've experienced situations where two different build servers - both in the US - returned a 404, while downloading from my house in Israel worked. This leads me to believe it's a regional caching issue with the CDN.
Just a complete guess here: perhaps it's worth disabling CDN caching for non-200 responses?