jackson-brain.com

UPDATE: There is a new version of this effort.

I needed to modify a local git servers web interface to indicate which revision a remote repo was currently on. This is what happened:

The PHP:

// make sure we have what we need
if( $_SERVER['REQUEST_METHOD'] == 'GET' && !empty($_GET['path'])){

    // our return array
    $return = array();

    // build the git command with the supplied path
    $gitCmd = 'git --git-dir='. $_GET['path'] . '.git --work-tree=' . $_GET['path'] . ' rev-parse HEAD';

    // configure the connection using the local keys
    $connection = ssh2_connect('host.domain.tld', 22, array('hostkey' => 'ssh-rsa'));

    // attempt to authenticate
    if( ssh2_auth_pubkey_file($connection, 'ssh_user', '/path/to/id_rsa.pub', '/path/to/id_rsa') ){

	// capture the return stream, blocking is set to ensure that we have data before we try to read from the stream
	$stream = ssh2_exec($connection, $gitCmd);
	stream_set_blocking($stream, true);

	// $result is the current head revision
	$result = stream_get_contents($stream);

	// make sure we have something and it's not FALSE
	if(!empty($result)){
	    $return['head'] = $result;
	}else{
	    $return['error'] = 'Error retrieving HEAD of remote repository.';
	}
    }else{
	// fail
	$return['error'] = 'SSH Authentication Failed.';
    }

    // send the data back as a json obj
    echo json_encode($return);
}

// done
die();

And the JS:

// update this object with the repos and their paths
var repoObject = {
    'repoName.git' : {
        'path' : '/path/to/local/repo/'
    }
};
// this is our success function
function querySuccess(data){
    // if we have errors, display them
    if( 'error' in data ){
	$('#query_error').text(data.error);
    }else{
        $('.' + data.head).addClass('currentHead');
    }
}
// we run this on document ready for great justice
$(function(){
    var repoTitle = $('#project_name').val();
    // only check rev if we are within a recognized repo
    if (  repoTitle in repoObject) {
        var rData = {
            'path' : repoObject[repoTitle].path
	    };
        $.ajax({
            dataType: 'json',
            url: '/get_head.php',
            data: rData,
            success: function(data){
	        querySuccess(data);
            },
            beforeSend: function(){
                $('#busy_anim').css('display','inline-block');
            },
            complete: function(){
                $('#busy_anim').css('display','none');
            }
        });
    }
});

You are going to want to ensure that you protect the keys you generate to do this, in this example they are in the web directory only protected by Apache.