It sounds like a usefull capability.

But presumably it depends on your localhost having a TCP/IP stack
and a http server installed.

It would be better if it could just use a socket or even just the filesystem.

J'

On Wed, Jul 20, 2016 at 05:25:30PM +0200, Ludovic Court??s wrote:
     Hi!
     
     Until now, if hydra.gnu.org had a source file in its store (the result
     of an ???origin???), you could get it via substitutes.  However, with
     substitutes disabled, hydra.gnu.org was of no help, even though it did
     have the source file.
     
     Commit ff6638d112d794c9c433731643711932452fd2ff helps address that: it
     augments ???guix publish??? such that it can be used as a content-addressed
     mirror for source files??.
     
     If you run ???guix publish -p 9999??? on your machine, and if
     hello-2.10.tar.gz is in the store, then this URL:
     
       http://localhost:9999/file/hello-2.10.tar.gz/sha256/0ssi1wpaf7plaswqqjwigppsg5fyh99vdlb9kzl7c9lng89ndq1i
     
     ??? gives you hello-2.10.tar.gz.
     
     This works by constructing the corresponding store file name, assuming
     the file being requested results from a fixed-output derivation using
     the same hash algorithm (SHA256 here) or was added with ???add-to-store???.
     That the hash algorithm must match is a limitation, but it???s probably
     ???good enough??? for our purposes.
     
     Eventually I think we???ll run it on our build farm and add the URL to
     ???%content-addressed-mirrors??? in (guix download).
     
     Feedback welcome.  :-)
     
     Ludo???.
     
     ?? https://lists.gnu.org/archive/html/guix-devel/2016-05/msg00450.html
     

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