A git post-receive hook to deploy from git repositories

unpacker.py

#!/usr/bin/env python
# unpacker.py
#  Author: Roger Gee <rpg11a@acu.edu>

# this script unpacks the lastest commit(s) on master and scans them
# for syncing; the script checks a file called '.unpack' which
# contains key/value pairs describing how to unpack the repository or
# any others into the filesystem; symlink this script as
# hooks/post-receive in the bare repository on your remote

import os
import re
import sys
import subprocess

# globals
REGEX = re.compile("^(.+?)=(.+)$")
BRANCH = "master"
LOCALFILE = "unpack.config"
CONFIGFILE = ".unpack"
localConfig = {
    
}
foreignConfig = {
    'entries': []
}

class GitRepo:
    def __init__(self,url,branch,**kwargs):
        self.url = url
        self.branch = branch

        if 'workcopy' in kwargs and os.path.isdir(kwargs['workcopy']):
            self.localCopy = kwargs['workcopy']
        else:
            pre = []
            for k in ['TEMPDIR','TMPDIR','TMP']:
                if k in os.environ:
                    pre.append(os.environ[k])
            if len(pre) == 0:
                pre.append('/tmp')
            self.localCopy = pre[0] + '/git-unpack'
            if not os.path.exists(self.localCopy):
                os.makedirs(self.localCopy)
            m = self.git_command("clone --branch {} {}".format(branch,url),"Cloning into '(.+?)'")
            self.localCopy += '/' + m.group(1)

    def get_latest_rev(self):
        return self.git_command("rev-parse {}".format(self.branch)).strip()

    def load_foreign_config(self):
        change_dir(self.localCopy)
        load_config(CONFIGFILE,update_foreign_config,True)
        change_dir()

    def sync_trees(self,tree,dst):
        change_dir(self.localCopy)
        if tree[len(tree)-1] != '/':
            tree += '/' # rsync requires this
        subprocess.check_call(['rsync','--exclude=.git/','--exclude=.unpack','-rvu','--chmod=ugo=rwX',tree,dst])
        change_dir()

    def git_command(self,cmdline,regex=""):
        # change working directories and run 'git'; if it returns
        # non-zero the function will throw an exception
        change_dir(self.localCopy)
        o = subprocess.check_output(['git']+cmdline.split(),stderr=subprocess.STDOUT)
        change_dir()

        if regex == "":
            return o

        lines = o.split("\n")
        rx = re.compile(regex)
        for line in lines:
            m = rx.match(line)
            if not m is None:
                return m
        raise Exception('git_command: regex did not match any output lines')

def change_dir(dirto=None):
    global oldCurrentDir
    if not dirto is None:
        oldCurrentDir = os.getcwd()
        os.chdir(dirto)
    elif not oldCurrentDir is None:
        os.chdir(oldCurrentDir)
        oldCurrentDir = None

def clean_exit(msg):
    sys.stdout.write(os.path.basename(sys.argv[0])+": "+msg+"\n")
    sys.exit(0)

def warn(msg):
    sys.stderr.write(os.path.basename(sys.argv[0])+": warning: "+msg+"\n")
    sys.exit(1)    

def fatal(msg):
    sys.stderr.write(os.path.basename(sys.argv[0])+": error: "+msg+"\n")
    sys.exit(1)

# update configuration values for the global local configuration
def update_local_config(key,value):
    global localConfig

    ks = map(str.strip,key.split('.'))
    i = 0
    thing = localConfig
    while i < len(ks)-1:
        if not ks[i] in thing:
            thing[ks[i]] = {}
        thing = ks[i]
        i += 1
    if ks[i] in thing:
        fatal("local config property is incorrect: '"+ks[i]+"'")
    thing[ks[i]] = value

# update and validate a specific configuration value for the global
# foreign configuration
def update_foreign_config(key,value):
    global foreignConfig

    if key == "entry":
        foreignConfig['entries'].append( value.split(':') )
    else:
        fatal("bad config key '"+key+"'")

# processes all unpacks specified in the unpacks file by updating the
# global configuration with their values
def load_config(unpackFile,fn,fatalFail):
    try:
        with open(unpackFile) as f:
            while True:
                line = f.readline()
                if len(line) > 0:
                    m = REGEX.match(line)
                    if not m is None:
                        fn(*map(str.strip,m.groups()))
                else:
                    break
    except IOError as e:
        if fatalFail:
            raise Exception("no config file '"+unpackFile+"' found in repository")

def save_config(configFile,config):
    with open(configFile,'w') as f:
        for (k,v) in config.iteritems():
            f.write(k+"="+v+"\n")

if 'GIT_DIR' in os.environ:
    del os.environ['GIT_DIR']

try:
    load_config(LOCALFILE,update_local_config,False)
    if 'workcopy' in localConfig:
        repo = GitRepo(os.getcwd(),BRANCH,workcopy=localConfig['workcopy'])
        repo.git_command("pull")
        rev = repo.get_latest_rev()
        if 'latest-rev' in localConfig and rev == localConfig['latest-rev']:
            clean_exit("no new revision available: stopping")
        localConfig['latest-rev'] = rev
    else:
        repo = GitRepo(os.getcwd(),BRANCH)
        localConfig['latest-rev'] = repo.get_latest_rev()
    localConfig['workcopy'] = repo.localCopy # this could have changed
    repo.load_foreign_config()
    if len(foreignConfig['entries']) == 0:
        raise Exception("no entries were specified in .unpack file")
    for (s,d) in foreignConfig['entries']:
        repo.sync_trees(s,d)
    change_dir()
    save_config(LOCALFILE,localConfig)
except Exception as e:
    change_dir()
    save_config(LOCALFILE,localConfig)
    fatal(str(e))