Add support for windows services

Circus can now control windows services local to the machine it is
running on. In order to configure a windows service watcher config now
requires an additional parameter:

proc_type = win_service

The cmd parameter only needs to contain the full name of the service.

circus/process.py

@@ -41,6 +41,11 @@
 OTHER = 3
 
 
+DEFAULT_PROCESS = "default"
+PAPA = "papa"
+WIN_SERVICE = "win_service"
+
+
 # psutil < 2.x compat
 def get_children(proc, recursive=False):
     try:

circus/watcher.py

@@ -29,6 +29,21 @@
 from circus.py3compat import bytestring, is_callable, b, PY2
 
 
+if IS_WINDOWS:
+    from circus.win_process import WinService
+    from circus.process import DEFAULT_PROCESS, PAPA, WIN_SERVICE
+    PROCESS_TYPES = {
+        DEFAULT_PROCESS: Process,
+        PAPA: PapaProcessProxy,
+        WIN_SERVICE: WinService
+    }
+else:
+    PROCESS_TYPES = {
+        DEFAULT_PROCESS: Process,
+        PAPA: PapaProcessProxy
+    }
+
+
 class Watcher(object):
 
     """
@@ -194,6 +209,9 @@ class Watcher(object):
 
     - **use_papa**: If True, use the papa process kernel for this process.
       default: False.
+
+    - **proc_type**: Type of the process to start. Local, win_service,
+      win_remote, linux_remote
     """
 
     def __init__(self, name, cmd, args=None, numprocesses=1, warmup_delay=0.,
@@ -209,7 +227,7 @@ def __init__(self, name, cmd, args=None, numprocesses=1, warmup_delay=0.,
                  stdin_socket=None, close_child_stdin=True,
                  close_child_stdout=False,
                  close_child_stderr=False, virtualenv_py_ver=None,
-                 use_papa=False, **options):
+                 use_papa=False, proc_type=None, **options):
         self.name = name
         self.use_sockets = use_sockets
         self.on_demand = on_demand
@@ -248,8 +266,14 @@ def __init__(self, name, cmd, args=None, numprocesses=1, warmup_delay=0.,
         self.close_child_stdout = close_child_stdout
         self.close_child_stderr = close_child_stderr
         self.use_papa = use_papa and papa is not None
+        self.proc_type = proc_type.lower() if proc_type else DEFAULT_PROCESS
+        self.proc_type = PAPA if self.use_papa else self.proc_type
         self.loop = loop or ioloop.IOLoop.instance()
 
+        if self.proc_type not in PROCESS_TYPES:
+            raise ValueError("Watcher: {}, Invalid process type supplied: {}"
+                             .format(self.name, self.proc_type))
+
         if singleton and self.numprocesses not in (0, 1):
             raise ValueError("Cannot have %d processes with a singleton "
                              " watcher" % self.numprocesses)
@@ -340,7 +364,7 @@ def _redirector_class(self):
 
     @property
     def _process_class(self):
-        return PapaProcessProxy if self.use_papa else Process
+        return PROCESS_TYPES[self.proc_type]
 
     def _reload_stream(self, key, val):
         parts = key.split('.', 1)
@@ -658,6 +682,7 @@ def spawn_process(self, recovery_wid=None):
             # noinspection PyPep8Naming
             ProcCls = self._process_class
             try:
+                logger.debug("Cmd: {}".format(cmd))
                 process = ProcCls(self.name, recovery_wid or self._nextwid,
                                   cmd, args=self.args,
                                   working_dir=self.working_dir,

circus/win_process.py

@@ -0,0 +1,178 @@
+import time
+import signal
+
+import psutil
+import wmi
+
+from circus import logger
+from circus import process
+from circus.util import debuglog
+
+
+class WinProcessError(OSError):
+    '''
+    All windows process/service specific errors must derive from this one.
+    '''
+
+SUCCESS = 0
+START_SERVICE_ECODES = {
+    SUCCESS: "The request was accepted.",
+    1: "The request is not supported.",
+    2: "The user did not have the necessary access.",
+    3: "The service cannot be stopped because other services that are running are dependent on it.",
+    4: "The requested control code is not valid, or it is unacceptable to the service.",
+    5: "The requested control code cannot be sent to the service because the "
+       "the service is not supporting this request, or user doesn't have necessary access",
+    6: "The service has not been started.",
+    7: "The service did not respond to the start request in a timely fashion.",
+    8: "Unknown failure when starting the service.",
+    9: "The directory path to the service executable file was not found.",
+    10: "The service is already running.",
+    11: "The database to add a new service is locked.",
+    12: "A dependency this service relies on has been removed from the system.",
+    13: "The service failed to find the service needed from a dependent service.",
+    14: "The service has been disabled from the system.",
+    15: "The service does not have the correct authentication to run on the system.",
+    16: "This service is being removed from the system.",
+    17: "The service has no execution thread.",
+    18: "The service has circular dependencies when it starts.",
+    19: "A service is running under the same name.",
+    20: "The service name has invalid characters.",
+    21: "Invalid parameters have been passed to the service.",
+    22: "The account under which this service runs is either invalid or lacks the permissions to run the service.",
+    23: "The service exists in the database of services available from the system.",
+    24: "The service is currently paused in the system.",
+}
+
+
+STOPPED = "Stopped"
+START_PENDING = "Start Pending"
+STOP_PENDING = "Stop Pending"
+RUNNING = "Running"
+CONT_PENDING = "Continue Pending"
+PAUSE_PENDING = "Pause Pending"
+PAUSED = "Paused"
+UNKNOWN = "Unknown"
+
+DISABLED = "Disabled"
+MANUAL = "Manual"
+
+
+class WinService(process.Process):
+    '''
+    Wraps windows service.
+    '''
+    def __init__(self, *args, **kwargs):
+        self._server = kwargs.pop("server") if "server" in kwargs else None
+        self._wmi = self._make_wmi_connection(self._server)
+        self._service = None
+
+        # Must call super last, otherwise spawn may be called before anything
+        # below __init__ get initialized
+        super().__init__(*args, **kwargs)
+
+    def _make_wmi_connection(self, server):
+        '''
+        Create the WMI connection to start the windows process.
+
+        @param server - name of the server on which the process needs to be
+                        started
+        '''
+        if server:
+            return wmi.WMI(computer=server)
+        else:
+            return wmi.WMI()
+
+    @property
+    def service(self):
+        '''
+        This property always returns a fresh copy of the service
+        '''
+        service = self._wmi.Win32_Service(displayname=self.cmd)\
+            or self._wmi.Win32_Service(name=self.cmd)
+
+        if not service:
+            raise WinProcessError("System can't find service: {}".format(self.cmd))
+        return service[0]
+
+    @debuglog
+    def poll(self):
+        return None if self.is_alive() else self.service.ExitCode
+
+    @debuglog
+    def is_alive(self):
+        return self._worker.is_running()
+
+    def returncode(self):
+        return self.poll()
+
+    @property
+    def stdout(self):
+        """Return the *stdout* stream"""
+        return None
+
+    @property
+    def stderr(self):
+        """Return the *stdout* stream"""
+        return None
+
+    @debuglog
+    def stop(self):
+        '''
+        Use WMI API to shutdown this service.
+        '''
+        if self.is_alive():
+            self._stop_service()
+
+    @debuglog
+    def send_signal(self, sig):
+        '''
+        Overwrite the default behavior to cleanly stop the windows service
+        using WMI if "sig" is SIGTERM.
+        '''
+        if sig == signal.SIGTERM:
+            logger.debug("sending signal %s to %s" % (sig, self.pid))
+            self._stop_service()
+        else:
+            super().send_signal(sig)
+
+    def spawn(self):
+        '''
+        Spawn a new instance of this process
+        '''
+        self.started = time.time()
+        if self.service.StartMode == DISABLED:
+            self._exec_service_command("ChangeStartMode", MANUAL)
+
+        self._stop_service()
+        self._exec_service_command("StartService")
+        self._worker = psutil.Process(self.service.ProcessID)
+
+    def _stop_service(self):
+        if self.service.State == STOPPED:
+            return
+
+        self.service.StopService()
+        if self.service.State == STOP_PENDING:
+            time.sleep(0.05)
+            if self.service.State != STOPPED:
+                raise WinProcessError("Unable to stop Windows Service: {}".format(self.cmd))
+
+    def _exec_service_command(self, command, *args):
+        '''
+        Helper method to execute WMI service commands
+
+        @param command - WMI method to execute
+        @param *args - arguments to the command method
+        '''
+        res = getattr(self.service, command)(*args)[0]
+        if res != SUCCESS:
+            raise self._make_error(res)
+
+    def _make_error(self, ecode):
+        '''
+        Helper method to make an exception and populate it with an appropriate
+        error.
+        '''
+        message = START_SERVICE_ECODES.get(ecode, "Unknown error occurred: {}".format(ecode))
+        return WinProcessError(message)