Re: bundles discovery and clones

From: Jeff King <peff@peff.net>
Date: Jun 11, 2024, 07:21 UTC
Message-ID: <20240611072144.GD3248245@coredump.intra.peff.net>
In-Reply-To: <CAHKF-AsoF10coLP=+MV-NfkEvWzp2Xbucs7OwtOoCBs3TVMg3A@mail.gmail.com>

On Mon, Jun 10, 2024 at 02:25:19PM -0400, matthew sporleder wrote:

Show 19 quoted lines

> I have recently been playing with git clone --bundle-uri and loving it
> because I can clone with almost-*zero* resources being used on the
> server!
> 
> I am a little confused by https://git-scm.com/docs/bundle-uri
> mentioning "discovery" and things. Is this something being added to
> the git cli, a special feature for other clients, or is it still too
> early-days to talk about much?
> 
> I would love to produce bundles of common use cases and have them
> auto-discovered by git clone *without* the --bundle-uri parameter, and
> then let our CDN do the heavy lifting of satisfying things like:
> git clone
> git clone --depth=0
> git clone --single-branch --branch main
> 
> I'm not sure I hold out as much hope for pre-bundling pulls/updates
> but any movement towards offloading our big-ish repos to CDNs is a win
> for us.

I don't think the server side is well documented, but peeking at the code, I think you want this on the server:

  git config uploadpack.advertiseBundleURIs true
  git config bundle.version 1
  git config bundle.mode any
  git config bundle.foo.uri https://example.com/your.bundle

And then the clients need to tell Git that they allow bundle transfers:

  git config --global transfer.bundleURI true

I'm not sure if we'd eventually flip the client-side switch to "true" by default (which is what you'd need for this to happen without any user participation at all).

One gotcha there is that clients are now accessing an arbitrary URL provided by the server, so there are cross-site security implications. It might make more sense to allow only relative URLs without ".." (so if I fetched from https://example.com/foo.git, the server could use only the relative "bundles/bar.bundle", which would then be found at https://example.com/foo.git/bundles/bar.bundle").

-Peff