Simple script to manage fcgi apps (useful for django applications)

wsgi-apps.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Copyright (C) 2010 Francesco Piccinno
#
# Author: Francesco Piccinno <stack.box@gmail.com>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

# Simple script to manage fcgi apps (django apps)

import os
import os.path
import sys

import logging
import logging.handlers

from subprocess import call

log = logging.getLogger('spawner')
log.setLevel(logging.DEBUG)
handler = logging.handlers.RotatingFileHandler(
    '/home/django/wsgi-apps.log', maxBytes=1024**2, backupCount=3)
formatter = logging.Formatter("%(asctime)s - %(name)s - %(levelname)s - %(message)s")
handler.setFormatter(formatter)
log.addHandler(handler)

PIDFILE_NAME      = '/home/django/pids/'
LOGGING_DIR       = '/home/django/logs/'

VIRTUALENV_PATH   = '/home/django/pyve/'
DEFAULT_ENV       = 'django'

APPLICATIONS_PATH = '/home/django/releases/'
KILL_BIN          = '/bin/kill'

apps = (
    {'app': 'test',
     'vhost': 'your.vhost-here.org',
     'virtualenv': 'django',
     'release': 'current',
     'port': 3034,
     'enabled': False,
    },
)

class Spawner(object):
    def __init__(self, apps):
        self.apps = apps

    def enabled_apps(self):
        return filter(
            lambda x: x.get('enabled', False) and True or False,
            self.apps
        )

    def get_app(self, name):
        for app in self.apps:
            if app['app'] == name:
                return app

    def croncheck(self):
        log.info('Checking health of enabled apps')
        for app in self.enabled_apps():
            self.croncheck_app(app)

    def croncheck_app(self, app):
        pid = self.get_app_pid(app)

        if pid == 0 or not self.is_running(pid):
            log.info('%s app is not running. Restarting..' % app['app'])
            try:
                self.start_app(app)
            except Exception, exc:
                log.debug("Error in start_app(%s) -> %s" % \
                          (str(app), str(exc)))

    def list(self):
        for app in self.enabled_apps():
            self.list_app(app)
            print >>sys.stderr

    def list_app(self, app):
        print >>sys.stderr, "{0:20} {1:20}".format('Key', 'Value')
        print >>sys.stderr, "="*20, "=" * 20

        for k, v in sorted(app.items()):
            print "{0:20} {1:20}".format(k, v)


    def status(self):
        print >>sys.stderr, "{0:20} {1:20}".format('Application', 'Status')
        print >>sys.stderr, "="*20, "=" * 20
        for app in self.enabled_apps():
            self.status_app(app)

    def status_app(self, app):
        pid = self.get_app_pid(app)
        print >>sys.stderr, "{0:20} {1:20}".format(
            app['app'],
            (pid != 0) and \
                'RUNNING (%d)' % pid or \
                'NOT RUNNING'
        )

    def get_app_pid(self, app):
        try:
            pidfile = open(os.path.join(
                PIDFILE_NAME,
                app.get('app') + '.pid',
            ), "r")

            pid = pidfile.read().strip()
            pidfile.close()

            return int(pid)
        except ValueError:
            return 0
        except IOError:
            return 0

    def stop(self):
        for app in self.enabled_apps():
            try:
                self.stop_app(app)
            except Exception, exc:
                log.debug("Error in stop_app(%s) -> %s" % \
                          (str(app), str(exc)))

    def is_running(self, pid):
        execstr = '%s -0 %d' % (KILL_BIN, pid)
        retcode = call(execstr, shell=True)

        if retcode == 0:
            return True
        return False

    def stop_app(self, app):
        pid = self.get_app_pid(app)

        if pid == 0:
            log.warning('Cannot stop %s app. It is not running' % app['app'])
            return False

        if self.is_running(pid):
            execstr = '%s -9 %d' % (KILL_BIN, pid)
            retcode = call(execstr, shell=True)

            if retcode == 0:
                os.unlink(os.path.join(
                    PIDFILE_NAME,
                    app.get('app') + ".pid",
                ))
                return True
            else:
                log.error('Killing the %s app (PID %d): failed.' % \
                          (app['app'], pid))
                return False

        else:
            log.warning('Cannot stop %s app (PID %d): ' \
                        'Operation not permitted or '   \
                        'application is not running' %  \
                        (app['app'], pid))
            return False

    def start(self):
        for app in self.enabled_apps():
            try:
                self.start_app(app)
            except Exception, exc:
                log.debug("Error in start_app(%s) -> %s" % \
                          (str(app), str(exc)))

    def start_app(self, app):
        log.info('Spawning %s' % app['app'])

        proj_dir = os.path.join(
            APPLICATIONS_PATH,
            app.get('vhost'),
            app.get('release', 'current'),
            app.get('app'),
        )

        env = app.get('virtualenv', DEFAULT_ENV)
        pybin = os.path.join(VIRTUALENV_PATH, env, 'bin', 'python')

        socket = os.path.join(SOCKET_DIR, app['app'] + '.socket')
        pidfile = os.path.join(PIDFILE_NAME, app['app'] + '.pid')

        errlog = os.path.join(LOGGING_DIR, app['app'] + '-errors.log')
        outlog = os.path.join(LOGGING_DIR, app['app'] + '-output.log')

        #'-v 0 outlog=%(outlog)s errlog=%(errlog)s ' \
        execstr = '%(python)s manage.py runfcgi host=127.0.0.1 port=%(port)s ' \
                  'method=%(method)s daemonize=true maxrequests=%(maxrequests)s ' \
                  'minspare=%(minspare)s maxspare=%(maxspare)s ' \
                  'protocol=scgi pidfile=%(pidfile)s' % ({ \
            'port': app['port'],
            'python': pybin,
            'socket': socket,
            'outlog': outlog,
            'errlog': errlog,
            'method': app.get('method', 'prefork'),
            'maxrequests': app.get('maxrequests', 20),
            'minspare': app.get('maxspare', 2),
            'maxspare': app.get('maxspare', 4),
            'pidfile': pidfile})

        log.debug('Switching to "%s"' % proj_dir)
        os.chdir(proj_dir)

        log.debug('Executing "%s"' % execstr)
        retcode = call(execstr, shell=True)

        if retcode != 0:
            log.error('Error while spawning %s (Return code: %d') % \
                (app.get('app'), retcode)
            return False

        return True

    def restart(self):
        self.stop()
        self.start()

    def restart_app(self, app):
        log.info('Restarting %s app' % app['app'])

        try:
            self.stop_app(app)
        except Exception, exc:
            log.debug("Error in stop_app(%s) -> %s" % \
                          (str(app), str(exc)))

        try:
            self.start_app(app)
        except Exception, exc:
            log.debug("Error in start_app(%s) -> %s" % \
                          (str(app), str(exc)))

if len(sys.argv) < 2 or len(sys.argv) > 3:
    print("Usage: %s <start>|<stop>|<restart>|<list>|<croncheck> [app]" % sys.argv[0])
    sys.exit(-1)

spawn = Spawner(apps)

if sys.argv[1] in ('start', 'stop', 'restart', 'status', 'croncheck', 'list'):
    app = None

    if len(sys.argv) == 3:
        app = spawn.get_app(sys.argv[2])

    if app:
        getattr(spawn, sys.argv[1] + '_app')(app)
    else:
        getattr(spawn, sys.argv[1])()