twistd-style nodejs daemonizer

noded.py

#!/usr/bin/env python
# Copyright (c) 2010 Jeff Lindsay
#
# Permission is hereby granted, free of charge, to any person
# obtaining a copy of this software and associated documentation
# files (the "Software"), to deal in the Software without
# restriction, including without limitation the rights to use,
# copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the
# Software is furnished to do so, subject to the following
# conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
# OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
# HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
# OTHER DEALINGS IN THE SOFTWARE.
#
# Usage: noded.py [options] script
# 
# Daemonizes a node.js script with various options
# 
# Options:
#   -h, --help            show this help message and exit
#   -l LOGFILE, --logfile=LOGFILE
#                         log stdout to a file [default: noded.log]
#   -p PIDFILE, --pidfile=PIDFILE
#                         write the PID to a file [default: noded.pid]
#   -u UID, --uid=UID     set the process user
#   -g GID, --gid=GID     set the process group
#   -c CHROOT, --chroot=CHROOT
#                         chroot the process
#   -b BINARY, --binary=BINARY
#                         path to node binary [default: node]

import sys, os, pwd, grp, tempfile
from optparse import OptionParser

wrapper = """var fs = require('fs'), script = process.binding('evals').Script;
fs.writeFileSync('%(pidfile)s', process.pid.toString());
global['exports']   = exports;
global['require']   = require;
global['module']    = module;
global['__filename']= __filename;
global['__dirname'] = __dirname;
script.runInThisContext(fs.readFileSync('%(script)s'), global, '%(script)s');
if (%(uid)s) { process.setuid(%(uid)s); }
if (%(gid)s) { process.setgid(%(gid)s); }"""

def daemonize (stdin='/dev/null', stdout='/dev/null', stderr='/dev/null'):
    '''Originally from: http://www.noah.org/wiki/Daemonize_Python'''
    try: 
        pid = os.fork() 
        if pid > 0:
            sys.exit(0)   # Exit first parent.
    except OSError, e: 
        sys.stderr.write ("fork #1 failed: (%d) %s\n" % (e.errno, e.strerror) )
        sys.exit(1)
    os.umask(0) 
    os.setsid() 
    try: 
        pid = os.fork() 
        if pid > 0:
            sys.exit(0)   # Exit second parent.
    except OSError, e: 
        sys.stderr.write ("fork #2 failed: (%d) %s\n" % (e.errno, e.strerror) )
        sys.exit(1)
    si = open(stdin, 'r')
    so = open(stdout, 'a+')
    se = open(stderr, 'a+', 0)
    os.dup2(si.fileno(), sys.stdin.fileno())
    os.dup2(so.fileno(), sys.stdout.fileno())
    os.dup2(se.fileno(), sys.stderr.fileno())

if __name__ == "__main__":
    parser = OptionParser("usage: %prog [options] script", description="Daemonizes a node.js script with various options")
    parser.add_option("-l", "--logfile",    dest="logfile", help="log stdout to a file [default: noded.log]",    default='noded.log')
    parser.add_option("-p", "--pidfile",    dest="pidfile", help="write the PID to a file [default: noded.pid]", default='noded.pid')
    parser.add_option("-u", "--uid",        dest="uid",     help="set the process user")
    parser.add_option("-g", "--gid",        dest="gid",     help="set the process group")
    parser.add_option("-c", "--chroot",     dest="chroot",  help="chroot the process")
    parser.add_option("-b", "--binary",     dest="binary",  help="path to node binary [default: node]", default='node')
    (options, args) = parser.parse_args()
    if len(args) == 0:
        parser.print_help()
        exit()
    daemonize('/dev/null', options.logfile, options.logfile)
    if options.uid: options.uid = pwd.getpwnam(options.uid)[2]
    if options.gid: options.gid = grp.getgrnam(options.gid)[2]
    with tempfile.NamedTemporaryFile(delete=False,suffix='.'+args[0].replace('/', '-')) as f:
        f.write(wrapper % dict(
            pidfile=options.pidfile,
            script=args[0],
            uid=options.uid or 'null',
            gid=options.gid or 'null'))
        script = f.name
    if options.chroot:
        os.execvp('chroot', ['chroot', options.chroot, options.binary, script])
    else:
        os.execvp(options.binary, [options.binary, script])