Re: Weird interaction between Git protocol versions and git:// and https:// URLs (was: Re: Bug with Git shallow clones and submodules)

On Sat, Sep 04, 2021 at 08:57:56AM -0400, Jeff King wrote:

The server has to be configured correctly at the HTTP level, too. The v2
probe for HTTP is a "Git-Protocol: version=2" header in the HTTP
request. The webserver has to be configured to communicate that to the
rest of Git somehow. In our test setup for Apache, we do:

  SetEnvIf Git-Protocol ".*" GIT_PROTOCOL=$0

If that doesn't happen, then the server doesn't see the header at all,
and just speaks v0 as usual.

I suspect this could be better documented.

Indeed, I was surprised to find out that all this time we were serving v0 for
http requests. /o\

For the record, the magic nginx+uwsgi incantation is:

    uwsgi_param GIT_PROTOCOL $http_git_protocol;

that gets us what we want:

    $ GIT_TRACE_PACKET=1 GIT_TRACE_BARE=1 git ls-remote https://git.kernel.org/pub/scm/git/git.git 2>&1 | grep version
    packet:          git< version 2
    packet:          git< version 2
    packet:          git< version 2

I will submit a patch for the docs to indicate that this is required, because
right now the only mention of GIT_PROTOCOL env variable are for the file://
and ssh:// schemes.

-K