Hackage url compatibility

[andreabedini]

To maximise hackage compatibility we should produce the same urls. Here's a list of what Hackage provides (extracted from https://hackage.haskell.org/api).

• /package/<pkg-id>/<pkg-id>.tar.gz

This is confusing, and indeed this note on hacakge-security starts with:

The situation with paths in cabal/hackage is a bit of a mess.

Reading that note and comparing with the code, I gather that:

• The "official" hackage path is /package/<pkg-id>/<pkg-id>.tar.gz
• Hackage provides a redirect from /package/<pkg-id>.tar.gz to /package/<pkg-id>/<pkg-id>.tar.gz
• cabal-install still uses /package/<pkg-id>.tar.gz

We have been using package/{pkg-id}.tar.gz and everything has been working fine, I guess we need to keep it like that. Note that a static website cannot serve a redirect (at least not in a general way).

• /package/{pkg-id}/{pkg-name}.cabal

This is the most recent cabal file. So far we expose this at index/{pkg-name}/{pkg-version}/{pkg-name}.cabal. Note: When first writing foliage, I used hackage-repo-tool as a blue print. hackage-repo-tool does create the /index paths, although they are not provided by Hackage, likely this is for compatibility with local indicies.

• /package/{pkg-id}/revision/{rev-number}.cabal

This is for all revisions. We don't have anything like this at the moment.

[andreabedini]

I had a second look, it's hackage-security that defines the layout for hackage, and it uses /package/<pkg-id>.tar.gz.

https://github.com/haskell/hackage-security/blob/482bc5a8c0215142e3ec224498453d2b5a25203c/hackage-security/src/Hackage/Security/TUF/Layout/Repo.hs#L52

I guess at this point it's irrelevant what hackage-server calls official :shrug: