scripts/services/service.py, thanks Ross
This commit is contained in:
Massimo Di Pierro
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from service import ServiceBase
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import os, sys, time, subprocess, atexit
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from signal import SIGTERM
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class LinuxService(ServiceBase):
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def __init__(self, name, label, stdout='/dev/null', stderr='/dev/null'):
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ServiceBase.__init__(self, name, label, stdout, stderr)
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self.pidfile = '/tmp/%s.pid' % name
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self.config_file = '/etc/%s.conf' % name
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def daemonize(self):
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"""
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do the UNIX double-fork magic, see Stevens' "Advanced
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Programming in the UNIX Environment" for details (ISBN 0201563177)
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http://www.erlenstar.demon.co.uk/unix/faq_2.html#SEC16
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"""
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try:
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pid = os.fork()
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if pid > 0:
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# exit first parent
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sys.exit(0)
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except OSError, e:
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sys.stderr.write("fork #1 failed: %d (%s)\n" % (e.errno, e.strerror))
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return
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# decouple from parent environment
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os.chdir("/")
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os.setsid()
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os.umask(0)
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# do second fork
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try:
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pid = os.fork()
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if pid > 0:
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# exit from second parent
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sys.exit(0)
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except OSError, e:
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sys.stderr.write("fork #2 failed: %d (%s)\n" % (e.errno, e.strerror))
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return
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# redirect standard file descriptors
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sys.stdout.flush()
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sys.stderr.flush()
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si = file('/dev/null', 'r')
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so = file(self.stdout or '/dev/null', 'a+')
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se = file(self.stderr or '/dev/null', 'a+')
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os.dup2(si.fileno(), sys.stdin.fileno())
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os.dup2(so.fileno(), sys.stdout.fileno())
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os.dup2(se.fileno(), sys.stderr.fileno())
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def getpid(self):
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# Check for a pidfile to see if the daemon already runs
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try:
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pf = file(self.pidfile,'r')
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pid = int(pf.read().strip())
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pf.close()
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except IOError:
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pid = None
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return pid
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def status(self):
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pid = self.getpid()
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if pid:
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return 'Service running with PID %s.' % pid
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else:
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return 'Service is not running.'
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def check_permissions(self):
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if not os.geteuid() == 0:
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return (False, 'This script must be run with root permissions.')
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else:
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return (True, '')
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def start(self):
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"""
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Start the daemon
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"""
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pid = self.getpid()
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if pid:
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message = "Service already running under PID %s\n"
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sys.stderr.write(message % self.pidfile)
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return
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# Start the daemon
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self.daemonize()
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self.run()
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def stop(self):
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"""
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Stop the daemon
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"""
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pid = self.getpid()
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if not pid:
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message = "Service is not running\n"
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sys.stderr.write(message)
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return # not an error in a restart
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# Try killing the daemon process
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try:
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while 1:
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os.kill(pid, SIGTERM)
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time.sleep(0.5)
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except OSError, err:
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err = str(err)
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if err.find("No such process") > 0:
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if os.path.exists(self.pidfile):
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os.remove(self.pidfile)
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else:
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print str(err)
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return
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def restart(self):
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"""
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Restart the daemon
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"""
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self.stop()
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self.start()
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def run(self):
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atexit.register(self.terminate)
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args = self.load_configuration()[0]
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stdout = open(self.stdout, 'a+')
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stderr = open(self.stderr, 'a+')
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process = subprocess.Popen(args, stdout=stdout, stderr=stderr)
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file(self.pidfile,'w+').write("%s\n" % process.pid)
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process.wait()
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self.terminate()
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def terminate(self):
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try:
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os.remove(self.pidfile)
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except:
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pass
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def install(self):
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env = self.detect_environment()
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src_path = os.path.join(os.path.dirname(os.path.abspath(__file__)), 'service.py')
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# make sure this script is executable
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self.run_command('chmod', '+x', src_path)
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# link this daemon to the service directory
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dest_path = env['rc.d-path'] + self.name
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os.symlink(src_path, dest_path)
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# start the service at boot
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install_command = self.get_service_installer_command(env)
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result = self.run_command(*install_command)
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self.start()
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def uninstall(self):
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self.stop()
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env = self.detect_environment()
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# stop the service from autostarting
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uninstall_command = self.get_service_uninstaller_command(env)
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result = self.run_command(*uninstall_command)
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# remove link to the script from the service directory
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path = env['rc.d-path'] + self.name
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os.remove(path)
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def detect_environment(self):
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"""
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Returns a dictionary of command/path to the required command-line applications.
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One key is 'dist' which will either be 'debian' or 'redhat', which is the best
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guess as to which Linux distribution the current system is based on.
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"""
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check_for = [
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'chkconfig',
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'service',
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'update-rc.d',
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'rpm',
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'dpkg',
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]
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env = dict()
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for cmd in check_for:
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result = self.run_command('which', cmd)
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if result[0]:
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env[cmd] = result[0].replace('\n', '')
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if 'rpm' in env:
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env['dist'] = 'redhat'
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env['rc.d-path'] = '/etc/rc.d/init.d/'
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elif 'dpkg' in env:
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env['dist'] = 'debian'
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env['rc.d-path'] = '/etc/init.d/'
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else:
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env['dist'] = 'unknown'
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env['rc.d-path'] = '/dev/null/'
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return env
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def get_service_installer_command(self, env):
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"""
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Returns list of args required to set a service to run on boot.
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"""
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if env['dist'] == 'redhat':
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cmd = env['chkconfig']
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return [cmd, self.name, 'on']
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else:
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cmd = env['update-rc.d']
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return [cmd, self.name, 'defaults']
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def get_service_uninstaller_command(self, env):
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"""
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Returns list of arge required to stop a service from running at boot.
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"""
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if env['dist'] == 'redhat':
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cmd = env['chkconfig']
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return [cmd, self.name, 'off']
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else:
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cmd = env['update-rc.d']
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return [cmd, self.name, 'remove']
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