Re: can we prevent reflog deletion when branch is deleted?

----- Original Message -----

From: "Jeff King" <redacted>
Sent: Thursday, November 14, 2013 3:14:56 AM
Subject: Re: can we prevent reflog deletion when branch is deleted?

On Thu, Nov 14, 2013 at 05:48:50AM +0530, Sitaram Chamarty wrote:

quoted

Is there *any* way we can preserve a reflog for a deleted branch,
perhaps under logs/refs/deleted/<timestamp>/full/ref/name ?

At GitHub, we log each change to an "audit log" in addition to the
regular reflog (we also stuff extra data from the environment into the
reflog message). So even after a branch is deleted, its audit log
entries remain, though you have to pull out the data by hand (git
doesn't know about it at all, except as an append-only sink for
writing). 

We recently ran into a similar situation at my $dayjob, so I made our
server side update hook log all pushes (including deletes) and added the
new log file to logrotate(8) -- note: make sure if logrotate recreates
the file that it allows everyone to write to it.  I'm sure it's not as
comprehensive as Peff's solution, but it's pretty simple for smaller
shops that want a little more protection.  Here are the relevant
excerpts from the script:

#!/usr/bin/env python

import os, sys, pwd, stat
from datetime import datetime

def log_push(too_many_changes):
    log_file = 'push-log.txt'
    try:
        f = open(log_file, 'a')

        try:
            # In case we just created the file, attempt to chmod it
            os.chmod(log_file, 0666)
        except OSError:
            # chmod will fail if the current user isn't the owner, but
            # if we've gotten this far we already have write permissions,
            # so just continue quietly
            pass

        # Linux/Mac okay, bad for Windows
        username = pwd.getpwuid(os.getuid())[0]
        f.write('%s: %s push by %s of %s from %s to %s\n'% \
                (datetime.now().strftime('%Y-%m-%d %H:%M:%S'),
                'Failed' if too_many_changes else 'Successful', username,
                refname, oldsha, newsha))
        f.close()
    except IOError:
        try:
            log_stats = os.stat(log_file)
            # Figure out owner and permissions
            log_owner = pwd.getpwuid(log_stats.st_uid).pw_name
            log_perm = oct(stat.S_IMODE(log_stats.st_mode))
            print_flush('Unable to open %s for appending. Current owner ' + \
                        'is %s and permissions are %s.'%(log_file,
                        log_owner, log_perm))
        except:
            exception,desc,stack = sys.exc_info()
            print_flush('Unable to open log file.  While generating error' + \
                        ' message encountered error: %s'%(desc))

if len(sys.argv) != 4:
    print_flush('Usage: %s refname oldsha newsha'%sys.argv[0])
    sys.exit(1)

refname = sys.argv[1]
oldsha = sys.argv[2]
newsha = sys.argv[3]

if newsha == '0'*40:
    # Deleted ref, nothing to do
    log_push(False)
    sys.exit(0)

# ... checking for various rule/style violations ...

log_push(too_many_changes)
if too_many_changes:
    sys.exit(1)
else:
    sys.exit(0)