Unique filenames for $revision.cabal.

[ghost]

Dear Haskell developers,

At the moment, versioned .cabal files are shipped under the name of $revision.cabal, e.g., 1.cabal. This makes it impossible to download many cabal files into a directory, because of the name clash.

Please, consider adding an url for the file with the name package-$revision.cabal.

Example:
In addition to having https://hackage.haskell.org/package/network-uri-2.6.4.2/revision/1.cabal, also add https://hackage.haskell.org/package/network-uri-2.6.4.2/revision/network-uri-2.6.4.2-1.cabal.

[ghost]

I think that something like that should be basically enough

diff --git a/datafiles/templates/Html/revisions.html.st b/datafiles/templates/Html/revisions.html.st
index 69cf2b75..f499d0ea 100644
--- a/datafiles/templates/Html/revisions.html.st
+++ b/datafiles/templates/Html/revisions.html.st
@@ -25,7 +25,7 @@ stored separately.
   </tr>
   $revisions:{revision|
     <tr>
-      <td valign="top"><a href="/package/$pkgid$/revision/$revision.number$.cabal">-r$revision.number$</a></td>
+      <td valign="top"><a href="/package/$pkgid$/revision/$revision.number$.cabal">-r$revision.number$</a>(<a href="/package/$pkgid$/revision/$pkgid$-$revision.number$.cabal">$pkgid$-r$revision.number$</a>)</td>
       <td valign="top">$revision.htmltime$</td>
       <td valign="top"><a href="/user/$revision.user$">$revision.user$</td>
       <td valign="top">$revision.sha256$</th>
diff --git a/src/Distribution/Server/Features/Core.hs b/src/Distribution/Server/Features/Core.hs
index 6aec793a..2247e771 100644
--- a/src/Distribution/Server/Features/Core.hs
+++ b/src/Distribution/Server/Features/Core.hs
@@ -225,6 +225,7 @@ data CoreResource = CoreResource {
     corePackageTarball  :: Resource,
     -- | A Cabal file metatada revision.
     coreCabalFileRev    :: Resource,
+    coreCabalFileRevName    :: Resource,
 
     -- Rendering resources.
     -- | URI for `corePackagesPage`, given a format (blank for none).
@@ -403,6 +404,7 @@ coreFeature ServerEnv{serverBlobStore = store} UserFeature{..}
           , coreCabalFile
           , coreCabalFileRevs
           , coreCabalFileRev
+          , coreCabalFileRevName
           , coreUserDeauth
           , coreAdminDeauth
           , corePackUserDeauth
@@ -456,6 +458,11 @@ coreFeature ServerEnv{serverBlobStore = store} UserFeature{..}
         resourceDesc = [(GET, "Get package .cabal file revision")]
       , resourceGet  = [("cabal", serveCabalFileRevision)]
       }
+    coreCabalFileRevName = (resourceAt "/package/:package/revision/:package-:revision.:format") {
+        resourceDesc = [(GET, "Get package .cabal file revision with name")]
+      , resourceGet  = [("cabal", serveCabalFileRevision)]
+      }
+
 
     coreUserDeauth = (resourceAt "/packages/deauth") {
         resourceDesc = [(GET,  "Deauth Package user")]

but I am not sure, I have never seen haskell before.

[andreabedini]

@lockywolf Just out of curiosity, would you mind describing what leads you to download many cabal files for different packages by their revision number? Thanks

[ghost]

Yes. I am following the Cabal Manual section 3.1.3.2

https://cabal.readthedocs.io/en/3.6/installing-packages.html#local-no-index-repositories

My goal is to create a fully offline "vendored" build of a Haskell binary executable. I am doing "cabal fetch", as well as download the fixed-revision cabal files (so that they can be verified against an md5sum) into a "downloads" directory.

With this issue resolved, I can just feed the list of downloads into any download tool, like wget, and get a redistributable directory.

Then, on a disconnected machine, I am doing a local "noindex" repo, and run cabal install. The "noindex" repo requires the cabal files to be named as bar-0.2.0.0.cabal, but be of the revision which allows them to get correctly built offline.

The script can be found here:

https://gitlab.com/Lockywolf/lwfslackbuilds/-/blob/master/61_agda/agda/agda.SlackBuild?ref_type=heads

The tentative pull-request which resolves this issue can be found here:

#1262

[phadej]

I also find 1.cabal naming not very convenient. However, I have tools (and I'm sure there are others out there too) which use current URLs, so I'd kindly ask that old URLs are also preserved if new paths are added.

[andreabedini]

@lockywolf in that case you only need one cabal file per package right?

Wouldn't be enough to grab that latest one from https://hackage.haskell.org/package/network-uri-2.6.4.2/network-uri.cabal?

In both cases you would still have to rename the file (a local repository expects network-uri-2.6.4.2.cabal) so I am not sure how the new path would improve the situation.

[ghost]

Wouldn't be enough to grab that latest one from

No, because with each update the md5 changes.

[andreabedini]

Thank you, I do understand the use-case better now but AFAIU you would still need to rename the file.

FWIW I put together a script for your use case (adapted from something similar I already had).

https://gist.github.com/andreabedini/79f20cf37a19fb78bbab8d0071999b23