Ability to run as daemon.

9 years ago · f28fd0aa34
parent 336dd0c541
commit f28fd0aa34
1 changed files with 170 additions and 16 deletions
--- a/src/scriptform.py
+++ b/src/scriptform.py
@ -24,6 +24,11 @@ import base64
 import tempfile
 import hashlib
 import urlparse
+import atexit
+import signal
+import time
+import errno
+import logging


 html_header = '''<html>
@ -159,6 +164,7 @@ class ScriptForm:
        else:
            self.callbacks = {}
        self.basepath = os.path.realpath(os.path.dirname(config_file))
+        self.log = logging.getLogger('SCRIPTFORM')

    def get_form_config(self):
        """
@ -498,7 +504,9 @@ class WebSrv:
    Very basic web server.
    """
    def __init__(self, request_handler, listen_addr='', listen_port=80):
+        self.log = logging.getLogger('WEBSRV')
        httpd = ThreadedHTTPServer((listen_addr, listen_port), request_handler)
+        self.log.info("Listening on {0}:{1}".format(listen_addr, listen_port))
        httpd.serve_forever()


@ -839,25 +847,141 @@ class ScriptFormWebApp(WebAppHandler):
                os.unlink(file_name)


-def main_generate_pw(parser, options, args):
-    import getpass
-    plain_pw = getpass.getpass()
-    if not plain_pw == getpass.getpass('Repeat password: '):
-        sys.stderr.write("Passwords do not match.\n")
-        sys.exit(1)
-    print hashlib.sha256(plain_pw).hexdigest()
-    sys.exit(0)
+class DaemonError(BaseException):
+    pass
+

-def main_serve(parser, options, args):
-    if len(args) < 1:
-        parser.error("Insufficient number of arguments")
+class Daemon:
+    """
+    Daemonize the current process (detach it from the console).
+    """
+    def __init__(self, pid_file, log_file=None, log_level=logging.INFO, foreground=False):
+        if pid_file is None:
+            self.pid_file = '{0}.pid'.format(os.path.basename(sys.argv[0]))
+        else:
+            self.pid_file = pid_file
+        if log_file is None:
+            self.log_file = '{0}.log'.format(os.path.basename(sys.argv[0]))
+        else:
+            self.log_file = log_file
+        self.foreground = foreground
+
+        logging.basicConfig(level=log_level,
+                            format='%(asctime)s:%(name)s:%(levelname)s:%(message)s',
+                            filename=self.log_file,
+                            filemode='a')
+        self.log = logging.getLogger('DAEMON')
+
+    def start(self):
+        self.log.info("Starting")
+        if self.is_running():
+            self.log.error('Already running')
+            raise DaemonError("Already running")
+        if not self.foreground:
+            self._fork()
+
+    def stop(self):
+        if not self.is_running():
+            raise DaemonError("Not running")
+
+        pid = self.get_pid()
+
+        # Kill the daemon and wait until the process is gone
+        os.kill(pid, signal.SIGTERM)
+        for timeout in range(25): # 5 seconds
+            time.sleep(0.2)
+            if not self._pid_running(pid):
+                break
+        else:
+            self.log.error("Couldn't stop the daemon.")
+
+    def is_running(self):
+        """
+        Check if the daemon is already running by looking at the PID file
+        """
+        if self.get_pid() is None:
+            return False
+        else:
+            return True
+
+    def get_pid(self):
+        """
+        Returns the PID of this daemon. If the daemon is not running (the PID
+        file does not exist or the PID in the PID file does not exist), returns
+        None.
+        """
+        if not os.path.exists(self.pid_file):
+            return None
+
+        try:
+            pid = int(file(self.pid_file, 'r').read().strip())
+        except ValueError:
+            return None
+
+        if os.path.isdir('/proc/{0}/'.format(pid)):
+            return pid
+        else:
+            os.unlink(self.pid_file)
+        return None
+
+    def _pid_running(self, pid):
+        """
+        Returns True if the PID is running, False otherwise
+        """
+        try:
+            os.kill(pid, 0)
+        except OSError as err:
+            if err.errno == errno.ESRCH:
+                return False
+        return True
+
+    def _fork(self):
+        # Fork a child and end the parent (detach from parent)
+        pid = os.fork()
+        if pid > 0:
+            sys.exit(0) # End parent
+
+        # Change some defaults so the daemon doesn't tie up dirs, etc.
+        os.setsid()
+        os.umask(0)
+
+        # Fork a child and end parent (so init now owns process)
+        pid = os.fork()
+        if pid > 0:
+            self.log.info("PID = {0}".format(pid))
+            f = file(self.pid_file, 'w')
+            f.write(str(pid))
+            f.close()
+            sys.exit(0) # End parent
+
+        atexit.register(self._cleanup)
+        signal.signal(signal.SIGTERM, self._cleanup)
+
+        # Close STDIN, STDOUT and STDERR so we don't tie up the controlling
+        # terminal
+        for fd in (0, 1, 2):
+            try:
+                os.close(fd)
+            except OSError:
+                pass
+
+        # Reopen the closed file descriptors so other os.open() calls don't
+        # accidentally get tied to the stdin etc.
+        os.open("/dev/null", os.O_RDWR)  # standard input (0)
+        os.dup2(0, 1)                    # standard output (1)
+        os.dup2(0, 2)                    # standard error (2)
+
+        return pid
+
+    def _cleanup(self, signal=None, frame=None):
+        self.log.info("Received signal {0}".format(signal))
+        if os.path.exists(self.pid_file):
+            os.unlink(self.pid_file)

-    sf = ScriptForm(args[0])
-    sf.run(listen_port=options.port)

 if __name__ == "__main__":
    usage = [
-        sys.argv[0] + " [option] <form_definition.json>",
+        sys.argv[0] + " [option] (--start|--stop) <form_definition.json>",
        "       " + sys.argv[0] + " --generate-pw",
    ]
    parser = optparse.OptionParser()
@ -865,9 +989,39 @@ if __name__ == "__main__":

    parser.add_option("-g", "--generate-pw", dest="generate_pw", action="store_true", default=False, help="Generate password")
    parser.add_option("-p", "--port", dest="port", action="store", type="int", default=80, help="Port to listen on")
+    parser.add_option("-f", "--foreground", dest="foreground", action="store_true", default=False, help="Run in foreground (debugging)")
+    parser.add_option(      "--pid-file", dest="pid_file", action="store", default=None, help="Pid file")
+    parser.add_option(      "--log-file", dest="log_file", action="store", default=None, help="Log file")
+    parser.add_option(      "--start", dest="action_start", action="store_true", default=None, help="Start daemon")
+    parser.add_option(      "--stop", dest="action_stop", action="store_true", default=None, help="Stop daemon")

    (options, args) = parser.parse_args()
+
    if options.generate_pw:
-        main_generate_pw(parser, options, args)
+        # Generate a password for use in the `users` section
+        import getpass
+        plain_pw = getpass.getpass()
+        if not plain_pw == getpass.getpass('Repeat password: '):
+            sys.stderr.write("Passwords do not match.\n")
+            sys.exit(1)
+        print hashlib.sha256(plain_pw).hexdigest()
+        sys.exit(0)
    else:
-        main_serve(parser, options, args)
+        if not options.action_stop and len(args) < 1:
+            parser.error("Insufficient number of arguments")
+        if not options.action_stop and not options.action_start:
+            options.action_start = True
+        daemon = Daemon(options.pid_file, options.log_file, foreground=options.foreground)
+        log = logging.getLogger('MAIN')
+        try:
+            if options.action_start:
+                sf = ScriptForm(args[0])
+                daemon.start()
+                #sf.run(listen_port=options.port)
+                time.sleep(10000)
+            elif options.action_stop:
+                daemon.stop()
+                sys.exit(0)
+        except Exception, e:
+            log.exception(e)
+            raise