plugins/hypervisors/baremetal/resources/security_group_agent/security_group_agent/sglib.py

#!/usr/bin/env python
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements.  See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
# under the License.
#
# Automatically generated by addcopyright.py at 01/29/2013

import sys, os, time, atexit
import traceback
import subprocess
from signal import SIGTERM 
import cherrypy
import copy

class Request(object):
    def __init__(self):
        self.headers = None
        self.body = None
        self.method = None
        self.query_string = None

    @staticmethod
    def from_cherrypy_request(creq):
        req = Request()
        req.headers = copy.copy(creq.headers)
        req.body = creq.body.fp.read() if creq.body else None
        req.method = copy.copy(creq.method)
        req.query_string = copy.copy(creq.query_string) if creq.query_string else None
        return req

class ShellError(Exception):
    '''shell error'''

class ShellCmd(object):
    '''
    classdocs
    '''
    def __init__(self, cmd, workdir=None, pipe=True):
        '''
        Constructor
        '''
        self.cmd = cmd
        if pipe:
            self.process = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE, stdin=subprocess.PIPE, stderr=subprocess.PIPE, executable='/bin/sh', cwd=workdir)
        else:
            self.process = subprocess.Popen(cmd, shell=True, executable='/bin/sh', cwd=workdir)

        self.stdout = None
        self.stderr = None
        self.return_code = None

    def __call__(self, is_exception=True):
        (self.stdout, self.stderr) = self.process.communicate()
        if is_exception and self.process.returncode != 0:
            err = []
            err.append('failed to execute shell command: %s' % self.cmd)
            err.append('return code: %s' % self.process.returncode)
            err.append('stdout: %s' % self.stdout)
            err.append('stderr: %s' % self.stderr)
            raise ShellError('\n'.join(err))

        self.return_code = self.process.returncode
        return self.stdout

class Daemon(object):
    """
    A generic daemon class.

    Usage: subclass the Daemon class and override the run() method
    """
    atexit_hooks = []

    def __init__(self, pidfile, stdin='/dev/null', stdout='/dev/null', stderr='/dev/null'):
        self.stdin = stdin
        self.stdout = stdout
        self.stderr = stderr
        self.pidfile = pidfile
    
    @staticmethod
    def register_atexit_hook(hook):
        Daemon.atexit_hooks.append(hook)
        
    @staticmethod
    def _atexit():
        for hook in Daemon.atexit_hooks:
            try:
                hook()
            except Exception:
                content = traceback.format_exc()
                err = 'Exception when calling atexit hook[%s]\n%s' % (hook.__name__, content)
                #logger.error(err)

    def daemonize(self):
        """
        do the UNIX double-fork magic, see Stevens' "Advanced
        Programming in the UNIX Environment" for details (ISBN 0201563177)
        http://www.erlenstar.demon.co.uk/unix/faq_2.html#SEC16
        """
        try:
            pid = os.fork()
            if pid > 0:
                # exit first parent
                sys.exit(0)
        except OSError, e:
            sys.stderr.write("fork #1 failed: %d (%s)\n" % (e.errno, e.strerror))
            sys.exit(1)

        # decouple from parent environment
        os.chdir("/")
        os.setsid()
        os.umask(0)

        # do second fork
        try:
            pid = os.fork()
            if pid > 0:
                # exit from second parent
                sys.exit(0)
        except OSError, e:
            sys.stderr.write("fork #2 failed: %d (%s)\n" % (e.errno, e.strerror))
            sys.exit(1)

        # redirect standard file descriptors
        sys.stdout.flush()
        sys.stderr.flush()
        si = file(self.stdin, 'r')
        so = file(self.stdout, 'a+')
        se = file(self.stderr, 'a+', 0)
        os.dup2(si.fileno(), sys.stdin.fileno())
        os.dup2(so.fileno(), sys.stdout.fileno())
        os.dup2(se.fileno(), sys.stderr.fileno())

        # write pidfile
        Daemon.register_atexit_hook(self.delpid)
        atexit.register(Daemon._atexit)
        pid = str(os.getpid())
        file(self.pidfile,'w').write("%s\n" % pid)

    def delpid(self):
        os.remove(self.pidfile)

    def start(self):
        """
        Start the daemon
        """
        # Check for a pidfile to see if the daemon already runs
        try:
            pf = file(self.pidfile,'r')
            pid = int(pf.read().strip())
            pf.close()
        except IOError:
            pid = None

        if pid:
            pscmd = ShellCmd('ps -p %s > /dev/null' % pid)
            pscmd(is_exception=False)
            if pscmd.return_code == 0:
                message = "Daemon already running, pid is %s\n"
                sys.stderr.write(message % pid)
                sys.exit(0)

        # Start the daemon
        self.daemonize()
        try:
            self.run()
        except Exception:
            content = traceback.format_exc()
            #logger.error(content)
            sys.exit(1)

    def stop(self):
        """
        Stop the daemon
        """
        # Get the pid from the pidfile
        try:
            pf = file(self.pidfile,'r')
            pid = int(pf.read().strip())
            pf.close()
        except IOError:
            pid = None

        if not pid:
            message = "pidfile %s does not exist. Daemon not running?\n"
            sys.stderr.write(message % self.pidfile)
            return # not an error in a restart

        # Try killing the daemon process
        try:
            while 1:
                os.kill(pid, SIGTERM)
                time.sleep(0.1)
        except OSError, err:
            err = str(err)
            if err.find("No such process") > 0:
                if os.path.exists(self.pidfile):
                    os.remove(self.pidfile)
            else:
                print str(err)
                sys.exit(1)

    def restart(self):
        """
        Restart the daemon
        """
        self.stop()
        self.start()

    def run(self):
        """
        You should override this method when you subclass Daemon. It will be called after the process has been
        daemonized by start() or restart().
        """