Re: Git 2 force commits but Git 1 doesn't

[Michael Ward <mward@smartsoftwareinc.com>]

Versions in use are 2.27.2 and 1.8.3.1. This behavior is seen with 
regular pushes.

I'll look into the http-backend functionality. If that will help control 
that, we'll definitely want to use that instead. What surprises me, 
though, is that even with DAV a 1.8 client appears to work correctly in 
that it will warn the user that their push is about to clobber the head, 
but 2.27 doesn't.

Michael

On 6/22/20 3:21 PM, brian m. carlson wrote:
> On 2020-06-22 at 19:40:15, Michael Ward wrote:
>> We have some repositories we are hosting here using Apache's DAV module to
>> handle remote connections.
>>
>> The repositories are created using the following:
>>
>> mkdir [reponame].git
>> cd [reponame].git
>> git --bare init
>> git update-server-info
>>
>> Our Apache location directive is as follows:
>>
>> <Location /[reponame].git>
>>          DAV on
>>          AuthType Basic
>>          AuthName "Git"
>>          AuthBasicProvider ldap
>>          AuthLDAPUrl [ldap server info]
>>          <RequireAny>
>>                  require [ldap filter]
>>          </RequireAny>
>> </Location>
>>
>> The repository config generates with the values in the core section below,
>> and we add the receive and advice sections:
>>
>> [core]
>>          repositoryformatversion = 0
>>          filemode = true
>>          bare = true
>> [receive]
>>          denyNonFastForwards = true
>>          denyDeletes = true
>> [advice]
>>          pushFetchFirst = true
>>
>> The odd behavior comes when we have git 1 vs git 2 clients attempting to
>> push in changes on the same branch. Git 1 clients will prompt the user that
>> they are out of date and need to pull. Git 2 clients don't and will force
>> push and overwrite the head revision. This occurs with either Git 1 or Git 2
>> on the server.
> Are you seeing this behavior when users are doing a force push, or just
> a regular push?  I see that there exists code for the DAV-based protocol
> to fail if a user attempts a regular push and is out of date, but I
> haven't verified it works.
>
> If you're seeing this when users are doing a force push, then that's
> expected.  The receive.* options have no effect here, since those
> require an appropriate git process to run on the server, and you're
> using the dumb (DAV-based) protocol, not the smart protocol.  Therefore,
> no git process runs on the server, so all the checking is done on the
> client side and the client side allows force pushes with an appropriate
> option.
>
> If you want to have more control over what's pushed, you'll need to use
> the smart protocol instead, which is outlined in the git-http-backend
> documentation.
>
> As a note, there are a lot of differences between Git 2.0.0 and the
> latest version, Git 2.27.0, so it's probably best if you mention the
> full version when reporting issues.  You haven't mentioned the specific
> versions you're using, but it's possible if you're using the CentOS 6 or
> 7 versions that they simply didn't support force pushing in this way.