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git_mirror.py
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git_mirror.py
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# Copyright (c) 2015, Ralf Jung <[email protected]>
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# 1. Redistributions of source code must retain the above copyright notice, this
# list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
# ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#==============================================================================
import sys, os, os.path, subprocess
import configparser, itertools, re
import hmac, hashlib
import email.mime.text, email.utils, smtplib
mail_sender = "null@localhost"
config_file = os.path.join(os.path.dirname(__file__), 'git-mirror.conf')
def Popen_quirky(cmd, **args):
'''
Runs cmd via subprocess.Popen; and if that fails, puts it into the shell (/bin/sh).
It seems that's what executing things in bash does, and even execve. Also,
all so-far released versions of Gitolite get the shebang line wrong.
'''
try:
return subprocess.Popen(cmd, **args)
except OSError as e:
return subprocess.Popen(['/bin/sh'] + cmd, **args)
class GitCommand:
def __getattr__(self, name):
def call(*args, capture_stderr = False, check = True):
'''If <capture_stderr>, return stderr merged with stdout. Otherwise, return stdout and forward stderr to our own.
If <check> is true, throw an exception of the process fails with non-zero exit code. Otherwise, do not.
In any case, return a pair of the captured output and the exit code.'''
cmd = ["git", name.replace('_', '-')] + list(args)
with subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT if capture_stderr else sys.stderr) as p:
(stdout, stderr) = p.communicate()
assert stderr is None
code = p.returncode
if check and code:
raise Exception("Error running {}: Non-zero exit code".format(cmd))
return (stdout.decode('utf-8').strip('\n'), code)
return call
git = GitCommand()
git_nullsha = 40*"0"
def git_is_forced_update(oldsha, newsha):
out, code = git.merge_base("--is-ancestor", oldsha, newsha, check = False) # "Check if the first <commit> is an ancestor of the second <commit>"
assert not out
assert code in (0, 1)
return False if code == 0 else True # if oldsha is an ancestor of newsha, then this was a "good" (non-forced) update
def read_config(defSection = 'DEFAULT'):
'''Reads a config file that may have options outside of any section.'''
config = configparser.ConfigParser()
with open(config_file) as file:
stream = itertools.chain(("["+defSection+"]\n",), file)
config.read_file(stream)
return config
def send_mail(subject, text, recipients, sender, replyTo = None):
assert isinstance(recipients, list)
if not len(recipients): return # nothing to do
# construct content
msg = email.mime.text.MIMEText(text.encode('UTF-8'), 'plain', 'UTF-8')
msg['Subject'] = subject
msg['Date'] = email.utils.formatdate(localtime=True)
msg['From'] = sender
msg['To'] = ', '.join(recipients)
if replyTo is not None:
msg['Reply-To'] = replyTo
# put into envelope and send
s = smtplib.SMTP('localhost')
s.sendmail(sender, recipients, msg.as_string())
s.quit()
class Repo:
def __init__(self, name, conf):
'''Creates a repository from a section of the git-mirror configuration file'''
self.name = name
self.local = conf['local']
self.owner = conf['owner'] # email address to notify in case of problems
self.hmac_secret = conf['hmac-secret'].encode('utf-8') if 'hmac-secret' in conf else None
self.deploy_key = conf['deploy-key'] # the SSH ky used for authenticating against remote hosts
self.mirrors = {} # maps mirrors to their URLs
mirror_prefix = 'mirror-'
for name in filter(lambda s: s.startswith(mirror_prefix), conf.keys()):
mirror = name[len(mirror_prefix):]
self.mirrors[mirror] = conf[name]
def mail_owner(self, msg):
global mail_sender
send_mail("git-mirror {}".format(self.name), msg, recipients = [self.owner], sender = mail_sender)
def compute_hmac(self, data):
assert self.hmac_secret is not None
h = hmac.new(self.hmac_secret, digestmod = hashlib.sha1)
h.update(data)
return h.hexdigest()
def find_mirror_by_url(self, match_urls):
for mirror, url in self.mirrors.items():
if url in match_urls:
return mirror
return None
def setup_env(self):
'''Setup the environment to work with this repository'''
os.chdir(self.local)
ssh_set_ident = os.path.join(os.path.dirname(__file__), 'ssh-set-ident.sh')
os.putenv('GIT_SSH', ssh_set_ident)
ssh_ident = os.path.join(os.path.expanduser('~/.ssh'), self.deploy_key)
os.putenv('GIT_MIRROR_SSH_IDENT', ssh_ident)
def update_mirrors(self, ref, oldsha, newsha):
'''Update the <ref> from <oldsha> to <newsha> on all mirrors. The update must already have happened locally.'''
assert len(oldsha) == 40 and len(newsha) == 40, "These are not valid SHAs."
source_mirror = os.getenv("GIT_MIRROR_SOURCE") # in case of a self-call via the hooks, we can skip one of the mirrors
self.setup_env()
# check for a forced update
is_forced = newsha != git_nullsha and oldsha != git_nullsha and git_is_forced_update(oldsha, newsha)
# tell all the mirrors
for mirror in self.mirrors:
if mirror == source_mirror:
continue
sys.stdout.write("Updating mirror {}\n".format(mirror)); sys.stdout.flush()
# update this mirror
if is_forced:
# forcibly update ref remotely (someone already did a force push and hence accepted data loss)
git.push('--force', self.mirrors[mirror], newsha+":"+ref)
else:
# nicely update ref remotely (this avoids data loss due to race conditions)
git.push(self.mirrors[mirror], newsha+":"+ref)
def update_ref_from_mirror(self, ref, oldsha, newsha, mirror, suppress_stderr = False):
'''Update the local version of this <ref> to what's currently on the given <mirror>. <oldsha> and <newsha> are checked. Then update all the other mirrors.'''
self.setup_env()
url = self.mirrors[mirror]
# first check whether the remote really is at newsha
remote_state, code = git.ls_remote(url, ref)
if remote_state:
remote_sha = remote_state.split()[0]
else:
remote_sha = git_nullsha
assert newsha == remote_sha, "Someone lied about the new SHA, which should be {}.".format(newsha)
# locally, we have to be at oldsha or newsha (the latter can happen if we already got this update, e.g. if it originated from us)
local_state, code = git.show_ref(ref, check=False)
if code == 0:
local_sha = local_state.split()[0]
else:
if len(local_state):
raise Exception("Something went wrong getting the local state of {}.".format(ref))
local_sha = git_nullsha
# some sanity checking, but deal gracefully with new branches appearing
assert local_sha in (git_nullsha, oldsha, newsha), "Someone lied about the old SHA: Local ({}) is neither old ({}) nor new ({})".format(local_sha, oldsha, newsha)
# if we are already at newsha locally, we also ran the local hooks, so we do not have to do anything
if local_sha == newsha:
return "Local repository is already up-to-date."
# update local state from local_sha to newsha.
if newsha != git_nullsha:
# We *could* now fetch the remote ref and immediately update the local one. However, then we would have to
# decide whether we want to allow a force-update or not. Also, the ref could already have changed remotely,
# so that may update to some other commit.
# Instead, we just fetch without updating any local ref. If the remote side changed in such a way that
# <newsha> is not actually fetched, that's a race and will be noticed when updating the local ref.
git.fetch(url, ref, capture_stderr = suppress_stderr)
# now update the ref, checking the old value is still local_oldsha.
git.update_ref(ref, newsha, 40*"0" if local_sha is None else local_sha)
else:
# ref does not exist anymore. delete it.
assert local_sha != git_nullsha, "Why didn't we bail out earlier if there is nothing to do...?"
git.update_ref("-d", ref, local_sha) # this checks that the old value is still local_sha
# Now run the post-receive hooks. This will *also* push the changes to all mirrors, as we
# are one of these hooks!
os.putenv("GIT_MIRROR_SOURCE", mirror) # tell ourselves which repo we do *not* have to update
with Popen_quirky(['hooks/post-receive'], stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.STDOUT) as p:
(stdout, stderr) = p.communicate("{} {} {}\n".format(oldsha, newsha, ref).encode('utf-8'))
stdout = stdout.decode('utf-8')
if p.returncode:
raise Exception("post-receive git hook terminated with non-zero exit code {}:\n{}".format(p.returncode, stdout))
return stdout
def find_repo_by_directory(repos, dir):
for (name, repo) in repos.items():
if dir == repo.local:
return name
return None
def load_repos():
global mail_sender
conf = read_config()
mail_sender = conf['DEFAULT']['mail-sender']
repos = {}
for name, section in conf.items():
if name != 'DEFAULT':
repos[name] = Repo(name, section)
return repos