Merge pull request #5760 from ivanov/connection-mixin

DRY out load_connection_file implementations

IPython/consoleapp.py

@@ -1,399 +1,353 b''
 """ A minimal application base mixin for all ZMQ based IPython frontends.
 
 This is not a complete console app, as subprocess will not be able to receive
 input, there is no real readline support, among other limitations. This is a
 refactoring of what used to be the IPython/qt/console/qtconsoleapp.py
-
-Authors:
-
-* Evan Patterson
-* Min RK
-* Erik Tollerud
-* Fernando Perez
-* Bussonnier Matthias
-* Thomas Kluyver
-* Paul Ivanov
-
 """
+# Copyright (c) IPython Development Team.
+# Distributed under the terms of the Modified BSD License.
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 # stdlib imports
 import atexit
-import json
 import os
 import signal
 import sys
 import uuid
 
 
 # Local imports
 from IPython.config.application import boolean_flag
 from IPython.core.profiledir import ProfileDir
 from IPython.kernel.blocking import BlockingKernelClient
 from IPython.kernel import KernelManager
 from IPython.kernel import tunnel_to_kernel, find_connection_file, swallow_argv
 from IPython.kernel.kernelspec import NoSuchKernel
 from IPython.utils.path import filefind
-from IPython.utils.py3compat import str_to_bytes
 from IPython.utils.traitlets import (
-    Dict, List, Unicode, CUnicode, Int, CBool, Any
+    Dict, List, Unicode, CUnicode, CBool, Any
 )
 from IPython.kernel.zmq.kernelapp import (
     kernel_flags,
     kernel_aliases,
     IPKernelApp
 )
 from IPython.kernel.zmq.pylab.config import InlineBackend
 from IPython.kernel.zmq.session import Session, default_secure
 from IPython.kernel.zmq.zmqshell import ZMQInteractiveShell
 from IPython.kernel.connect import ConnectionFileMixin
 
 #-----------------------------------------------------------------------------
 # Network Constants
 #-----------------------------------------------------------------------------
 
 from IPython.utils.localinterfaces import localhost
 
 #-----------------------------------------------------------------------------
 # Globals
 #-----------------------------------------------------------------------------
 
 
 #-----------------------------------------------------------------------------
 # Aliases and Flags
 #-----------------------------------------------------------------------------
 
 flags = dict(kernel_flags)
 
 # the flags that are specific to the frontend
 # these must be scrubbed before being passed to the kernel,
 # or it will raise an error on unrecognized flags
 app_flags = {
     'existing' : ({'IPythonConsoleApp' : {'existing' : 'kernel*.json'}},
             "Connect to an existing kernel. If no argument specified, guess most recent"),
 }
 app_flags.update(boolean_flag(
     'confirm-exit', 'IPythonConsoleApp.confirm_exit',
     """Set to display confirmation dialog on exit. You can always use 'exit' or 'quit',
        to force a direct exit without any confirmation.
     """,
     """Don't prompt the user when exiting. This will terminate the kernel
        if it is owned by the frontend, and leave it alive if it is external.
     """
 ))
 flags.update(app_flags)
 
 aliases = dict(kernel_aliases)
 
 # also scrub aliases from the frontend
 app_aliases = dict(
     ip = 'IPythonConsoleApp.ip',
     transport = 'IPythonConsoleApp.transport',
     hb = 'IPythonConsoleApp.hb_port',
     shell = 'IPythonConsoleApp.shell_port',
     iopub = 'IPythonConsoleApp.iopub_port',
     stdin = 'IPythonConsoleApp.stdin_port',
     existing = 'IPythonConsoleApp.existing',
     f = 'IPythonConsoleApp.connection_file',
 
     kernel = 'IPythonConsoleApp.kernel_name',
 
     ssh = 'IPythonConsoleApp.sshserver',
 )
 aliases.update(app_aliases)
 
 #-----------------------------------------------------------------------------
 # Classes
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # IPythonConsole
 #-----------------------------------------------------------------------------
 
 classes = [IPKernelApp, ZMQInteractiveShell, KernelManager, ProfileDir, Session, InlineBackend]
 
 class IPythonConsoleApp(ConnectionFileMixin):
     name = 'ipython-console-mixin'
 
     description = """
         The IPython Mixin Console.
         
         This class contains the common portions of console client (QtConsole,
         ZMQ-based terminal console, etc).  It is not a full console, in that
         launched terminal subprocesses will not be able to accept input.
         
         The Console using this mixing supports various extra features beyond
         the single-process Terminal IPython shell, such as connecting to
         existing kernel, via:
         
             ipython <appname> --existing
         
         as well as tunnel via SSH
         
     """
 
     classes = classes
     flags = Dict(flags)
     aliases = Dict(aliases)
     kernel_manager_class = KernelManager
     kernel_client_class = BlockingKernelClient
 
     kernel_argv = List(Unicode)
     # frontend flags&aliases to be stripped when building kernel_argv
     frontend_flags = Any(app_flags)
     frontend_aliases = Any(app_aliases)
 
     # create requested profiles by default, if they don't exist:
     auto_create = CBool(True)
     # connection info:
     
     sshserver = Unicode('', config=True,
         help="""The SSH server to use to connect to the kernel.""")
     sshkey = Unicode('', config=True,
         help="""Path to the ssh key to use for logging in to the ssh server.""")
     
-    hb_port = Int(0, config=True,
-        help="set the heartbeat port [default: random]")
-    shell_port = Int(0, config=True,
-        help="set the shell (ROUTER) port [default: random]")
-    iopub_port = Int(0, config=True,
-        help="set the iopub (PUB) port [default: random]")
-    stdin_port = Int(0, config=True,
-        help="set the stdin (DEALER) port [default: random]")
-    connection_file = Unicode('', config=True,
-        help="""JSON file in which to store connection info [default: kernel-<pid>.json]
-
-        This file will contain the IP, ports, and authentication key needed to connect
-        clients to this kernel. By default, this file will be created in the security-dir
-        of the current profile, but can be specified by absolute path.
-        """)
     def _connection_file_default(self):
         return 'kernel-%i.json' % os.getpid()
 
     existing = CUnicode('', config=True,
         help="""Connect to an already running kernel""")
 
     kernel_name = Unicode('python', config=True,
         help="""The name of the default kernel to start.""")
 
     confirm_exit = CBool(True, config=True,
         help="""
         Set to display confirmation dialog on exit. You can always use 'exit' or 'quit',
         to force a direct exit without any confirmation.""",
     )
 
 
     def build_kernel_argv(self, argv=None):
         """build argv to be passed to kernel subprocess"""
         if argv is None:
             argv = sys.argv[1:]
         self.kernel_argv = swallow_argv(argv, self.frontend_aliases, self.frontend_flags)
         # kernel should inherit default config file from frontend
         self.kernel_argv.append("--IPKernelApp.parent_appname='%s'" % self.name)
     
     def init_connection_file(self):
         """find the connection file, and load the info if found.
         
         The current working directory and the current profile's security
         directory will be searched for the file if it is not given by
         absolute path.
         
         When attempting to connect to an existing kernel and the `--existing`
         argument does not match an existing file, it will be interpreted as a
         fileglob, and the matching file in the current profile's security dir
         with the latest access time will be used.
         
         After this method is called, self.connection_file contains the *full path*
         to the connection file, never just its name.
         """
         if self.existing:
             try:
                 cf = find_connection_file(self.existing)
             except Exception:
                 self.log.critical("Could not find existing kernel connection file %s", self.existing)
                 self.exit(1)
             self.log.debug("Connecting to existing kernel: %s" % cf)
             self.connection_file = cf
         else:
             # not existing, check if we are going to write the file
             # and ensure that self.connection_file is a full path, not just the shortname
             try:
                 cf = find_connection_file(self.connection_file)
             except Exception:
                 # file might not exist
                 if self.connection_file == os.path.basename(self.connection_file):
                     # just shortname, put it in security dir
                     cf = os.path.join(self.profile_dir.security_dir, self.connection_file)
                 else:
                     cf = self.connection_file
                 self.connection_file = cf
+        try:
+            self.connection_file = filefind(self.connection_file, ['.', self.profile_dir.security_dir])
+        except IOError:
+            self.log.debug("Connection File not found: %s", self.connection_file)
+            return
         
         # should load_connection_file only be used for existing?
         # as it is now, this allows reusing ports if an existing
         # file is requested
         try:
             self.load_connection_file()
         except Exception:
             self.log.error("Failed to load connection file: %r", self.connection_file, exc_info=True)
             self.exit(1)
     
-    def load_connection_file(self):
-        """load ip/port/hmac config from JSON connection file"""
-        # this is identical to IPKernelApp.load_connection_file
-        # perhaps it can be centralized somewhere?
-        try:
-            fname = filefind(self.connection_file, ['.', self.profile_dir.security_dir])
-        except IOError:
-            self.log.debug("Connection File not found: %s", self.connection_file)
-            return
-        self.log.debug(u"Loading connection file %s", fname)
-        with open(fname) as f:
-            cfg = json.load(f)
-        self.transport = cfg.get('transport', 'tcp')
-        self.ip = cfg.get('ip', localhost())
-        
-        for channel in ('hb', 'shell', 'iopub', 'stdin', 'control'):
-            name = channel + '_port'
-            if getattr(self, name) == 0 and name in cfg:
-                # not overridden by config or cl_args
-                setattr(self, name, cfg[name])
-        if 'key' in cfg:
-            self.config.Session.key = str_to_bytes(cfg['key'])
-        if 'signature_scheme' in cfg:
-            self.config.Session.signature_scheme = cfg['signature_scheme']
-    
     def init_ssh(self):
         """set up ssh tunnels, if needed."""
         if not self.existing or (not self.sshserver and not self.sshkey):
             return
         self.load_connection_file()
         
         transport = self.transport
         ip = self.ip
         
         if transport != 'tcp':
             self.log.error("Can only use ssh tunnels with TCP sockets, not %s", transport)
             sys.exit(-1)
         
         if self.sshkey and not self.sshserver:
             # specifying just the key implies that we are connecting directly
             self.sshserver = ip
             ip = localhost()
         
         # build connection dict for tunnels:
         info = dict(ip=ip,
                     shell_port=self.shell_port,
                     iopub_port=self.iopub_port,
                     stdin_port=self.stdin_port,
                     hb_port=self.hb_port
         )
         
         self.log.info("Forwarding connections to %s via %s"%(ip, self.sshserver))
         
         # tunnels return a new set of ports, which will be on localhost:
         self.ip = localhost()
         try:
             newports = tunnel_to_kernel(info, self.sshserver, self.sshkey)
         except:
             # even catch KeyboardInterrupt
             self.log.error("Could not setup tunnels", exc_info=True)
             self.exit(1)
         
         self.shell_port, self.iopub_port, self.stdin_port, self.hb_port = newports
         
         cf = self.connection_file
         base,ext = os.path.splitext(cf)
         base = os.path.basename(base)
         self.connection_file = os.path.basename(base)+'-ssh'+ext
         self.log.info("To connect another client via this tunnel, use:")
         self.log.info("--existing %s" % self.connection_file)
     
     def _new_connection_file(self):
         cf = ''
         while not cf:
             # we don't need a 128b id to distinguish kernels, use more readable
             # 48b node segment (12 hex chars).  Users running more than 32k simultaneous
             # kernels can subclass.
             ident = str(uuid.uuid4()).split('-')[-1]
             cf = os.path.join(self.profile_dir.security_dir, 'kernel-%s.json' % ident)
             # only keep if it's actually new.  Protect against unlikely collision
             # in 48b random search space
             cf = cf if not os.path.exists(cf) else ''
         return cf
 
     def init_kernel_manager(self):
         # Don't let Qt or ZMQ swallow KeyboardInterupts.
         if self.existing:
             self.kernel_manager = None
             return
         signal.signal(signal.SIGINT, signal.SIG_DFL)
 
         # Create a KernelManager and start a kernel.
         try:
             self.kernel_manager = self.kernel_manager_class(
                                     ip=self.ip,
                                     transport=self.transport,
                                     shell_port=self.shell_port,
                                     iopub_port=self.iopub_port,
                                     stdin_port=self.stdin_port,
                                     hb_port=self.hb_port,
                                     connection_file=self.connection_file,
                                     kernel_name=self.kernel_name,
                                     parent=self,
                                     ipython_dir=self.ipython_dir,
             )
         except NoSuchKernel:
             self.log.critical("Could not find kernel %s", self.kernel_name)
             self.exit(1)
 
         self.kernel_manager.client_factory = self.kernel_client_class
         self.kernel_manager.start_kernel(extra_arguments=self.kernel_argv)
         atexit.register(self.kernel_manager.cleanup_ipc_files)
 
         if self.sshserver:
             # ssh, write new connection file
             self.kernel_manager.write_connection_file()
 
         # in case KM defaults / ssh writing changes things:
         km = self.kernel_manager
         self.shell_port=km.shell_port
         self.iopub_port=km.iopub_port
         self.stdin_port=km.stdin_port
         self.hb_port=km.hb_port
         self.connection_file = km.connection_file
 
         atexit.register(self.kernel_manager.cleanup_connection_file)
 
     def init_kernel_client(self):
         if self.kernel_manager is not None:
             self.kernel_client = self.kernel_manager.client()
         else:
             self.kernel_client = self.kernel_client_class(
                                 ip=self.ip,
                                 transport=self.transport,
                                 shell_port=self.shell_port,
                                 iopub_port=self.iopub_port,
                                 stdin_port=self.stdin_port,
                                 hb_port=self.hb_port,
                                 connection_file=self.connection_file,
                                 parent=self,
             )
 
         self.kernel_client.start_channels()
 
 
 
     def initialize(self, argv=None):
         """
         Classes which mix this class in should call:
                IPythonConsoleApp.initialize(self,argv)
         """
         self.init_connection_file()
         default_secure(self.config)
         self.init_ssh()
         self.init_kernel_manager()
         self.init_kernel_client()
 

IPython/kernel/connect.py

@@ -1,562 +1,569 b''
 """Utilities for connecting to kernels
 
-Authors:
-
-* Min Ragan-Kelley
-
+Notable contents: 
+- ConnectionFileMixin class
+    encapsulates the logic related to writing and reading connections files.
 """
-
-#-----------------------------------------------------------------------------
-#  Copyright (C) 2013  The IPython Development Team
-#
-#  Distributed under the terms of the BSD License.  The full license is in
-#  the file COPYING, distributed as part of this software.
-#-----------------------------------------------------------------------------
+# Copyright (c) IPython Development Team.
+# Distributed under the terms of the Modified BSD License.
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 from __future__ import absolute_import
 
 import glob
 import json
 import os
 import socket
 import sys
 from getpass import getpass
 from subprocess import Popen, PIPE
 import tempfile
 
 import zmq
 
 # external imports
 from IPython.external.ssh import tunnel
 
 # IPython imports
 from IPython.config import Configurable
 from IPython.core.profiledir import ProfileDir
 from IPython.utils.localinterfaces import localhost
 from IPython.utils.path import filefind, get_ipython_dir
 from IPython.utils.py3compat import (str_to_bytes, bytes_to_str, cast_bytes_py2,
                                      string_types)
 from IPython.utils.traitlets import (
     Bool, Integer, Unicode, CaselessStrEnum,
 )
 
 
 #-----------------------------------------------------------------------------
 # Working with Connection Files
 #-----------------------------------------------------------------------------
 
 def write_connection_file(fname=None, shell_port=0, iopub_port=0, stdin_port=0, hb_port=0,
                          control_port=0, ip='', key=b'', transport='tcp',
                          signature_scheme='hmac-sha256',
                          ):
     """Generates a JSON config file, including the selection of random ports.
     
     Parameters
     ----------
 
     fname : unicode
         The path to the file to write
 
     shell_port : int, optional
         The port to use for ROUTER (shell) channel.
 
     iopub_port : int, optional
         The port to use for the SUB channel.
 
     stdin_port : int, optional
         The port to use for the ROUTER (raw input) channel.
 
     control_port : int, optional
         The port to use for the ROUTER (control) channel.
 
     hb_port : int, optional
         The port to use for the heartbeat REP channel.
 
     ip  : str, optional
         The ip address the kernel will bind to.
 
     key : str, optional
         The Session key used for message authentication.
     
     signature_scheme : str, optional
         The scheme used for message authentication.
         This has the form 'digest-hash', where 'digest'
         is the scheme used for digests, and 'hash' is the name of the hash function
         used by the digest scheme.
         Currently, 'hmac' is the only supported digest scheme,
         and 'sha256' is the default hash function.
 
     """
     if not ip:
         ip = localhost()
     # default to temporary connector file
     if not fname:
         fd, fname = tempfile.mkstemp('.json')
         os.close(fd)
     
     # Find open ports as necessary.
     
     ports = []
     ports_needed = int(shell_port <= 0) + \
                    int(iopub_port <= 0) + \
                    int(stdin_port <= 0) + \
                    int(control_port <= 0) + \
                    int(hb_port <= 0)
     if transport == 'tcp':
         for i in range(ports_needed):
             sock = socket.socket()
             # struct.pack('ii', (0,0)) is 8 null bytes
             sock.setsockopt(socket.SOL_SOCKET, socket.SO_LINGER, b'\0' * 8)
             sock.bind(('', 0))
             ports.append(sock)
         for i, sock in enumerate(ports):
             port = sock.getsockname()[1]
             sock.close()
             ports[i] = port
     else:
         N = 1
         for i in range(ports_needed):
             while os.path.exists("%s-%s" % (ip, str(N))):
                 N += 1
             ports.append(N)
             N += 1
     if shell_port <= 0:
         shell_port = ports.pop(0)
     if iopub_port <= 0:
         iopub_port = ports.pop(0)
     if stdin_port <= 0:
         stdin_port = ports.pop(0)
     if control_port <= 0:
         control_port = ports.pop(0)
     if hb_port <= 0:
         hb_port = ports.pop(0)
     
     cfg = dict( shell_port=shell_port,
                 iopub_port=iopub_port,
                 stdin_port=stdin_port,
                 control_port=control_port,
                 hb_port=hb_port,
               )
     cfg['ip'] = ip
     cfg['key'] = bytes_to_str(key)
     cfg['transport'] = transport
     cfg['signature_scheme'] = signature_scheme
     
     with open(fname, 'w') as f:
         f.write(json.dumps(cfg, indent=2))
     
     return fname, cfg
 
 
 def get_connection_file(app=None):
     """Return the path to the connection file of an app
     
     Parameters
     ----------
     app : IPKernelApp instance [optional]
         If unspecified, the currently running app will be used
     """
     if app is None:
         from IPython.kernel.zmq.kernelapp import IPKernelApp
         if not IPKernelApp.initialized():
             raise RuntimeError("app not specified, and not in a running Kernel")
 
         app = IPKernelApp.instance()
     return filefind(app.connection_file, ['.', app.profile_dir.security_dir])
 
 
 def find_connection_file(filename, profile=None):
     """find a connection file, and return its absolute path.
     
     The current working directory and the profile's security
     directory will be searched for the file if it is not given by
     absolute path.
     
     If profile is unspecified, then the current running application's
     profile will be used, or 'default', if not run from IPython.
     
     If the argument does not match an existing file, it will be interpreted as a
     fileglob, and the matching file in the profile's security dir with
     the latest access time will be used.
     
     Parameters
     ----------
     filename : str
         The connection file or fileglob to search for.
     profile : str [optional]
         The name of the profile to use when searching for the connection file,
         if different from the current IPython session or 'default'.
     
     Returns
     -------
     str : The absolute path of the connection file.
     """
     from IPython.core.application import BaseIPythonApplication as IPApp
     try:
         # quick check for absolute path, before going through logic
         return filefind(filename)
     except IOError:
         pass
     
     if profile is None:
         # profile unspecified, check if running from an IPython app
         if IPApp.initialized():
             app = IPApp.instance()
             profile_dir = app.profile_dir
         else:
             # not running in IPython, use default profile
             profile_dir = ProfileDir.find_profile_dir_by_name(get_ipython_dir(), 'default')
     else:
         # find profiledir by profile name:
         profile_dir = ProfileDir.find_profile_dir_by_name(get_ipython_dir(), profile)
     security_dir = profile_dir.security_dir
     
     try:
         # first, try explicit name
         return filefind(filename, ['.', security_dir])
     except IOError:
         pass
     
     # not found by full name
     
     if '*' in filename:
         # given as a glob already
         pat = filename
     else:
         # accept any substring match
         pat = '*%s*' % filename
     matches = glob.glob( os.path.join(security_dir, pat) )
     if not matches:
         raise IOError("Could not find %r in %r" % (filename, security_dir))
     elif len(matches) == 1:
         return matches[0]
     else:
         # get most recent match, by access time:
         return sorted(matches, key=lambda f: os.stat(f).st_atime)[-1]
 
 
 def get_connection_info(connection_file=None, unpack=False, profile=None):
     """Return the connection information for the current Kernel.
     
     Parameters
     ----------
     connection_file : str [optional]
         The connection file to be used. Can be given by absolute path, or
         IPython will search in the security directory of a given profile.
         If run from IPython, 
         
         If unspecified, the connection file for the currently running
         IPython Kernel will be used, which is only allowed from inside a kernel.
     unpack : bool [default: False]
         if True, return the unpacked dict, otherwise just the string contents
         of the file.
     profile : str [optional]
         The name of the profile to use when searching for the connection file,
         if different from the current IPython session or 'default'.
         
     
     Returns
     -------
     The connection dictionary of the current kernel, as string or dict,
     depending on `unpack`.
     """
     if connection_file is None:
         # get connection file from current kernel
         cf = get_connection_file()
     else:
         # connection file specified, allow shortnames:
         cf = find_connection_file(connection_file, profile=profile)
     
     with open(cf) as f:
         info = f.read()
     
     if unpack:
         info = json.loads(info)
         # ensure key is bytes:
         info['key'] = str_to_bytes(info.get('key', ''))
     return info
 
 
 def connect_qtconsole(connection_file=None, argv=None, profile=None):
     """Connect a qtconsole to the current kernel.
     
     This is useful for connecting a second qtconsole to a kernel, or to a
     local notebook.
     
     Parameters
     ----------
     connection_file : str [optional]
         The connection file to be used. Can be given by absolute path, or
         IPython will search in the security directory of a given profile.
         If run from IPython, 
         
         If unspecified, the connection file for the currently running
         IPython Kernel will be used, which is only allowed from inside a kernel.
     argv : list [optional]
         Any extra args to be passed to the console.
     profile : str [optional]
         The name of the profile to use when searching for the connection file,
         if different from the current IPython session or 'default'.
     
     
     Returns
     -------
     subprocess.Popen instance running the qtconsole frontend
     """
     argv = [] if argv is None else argv
     
     if connection_file is None:
         # get connection file from current kernel
         cf = get_connection_file()
     else:
         cf = find_connection_file(connection_file, profile=profile)
     
     cmd = ';'.join([
         "from IPython.qt.console import qtconsoleapp",
         "qtconsoleapp.main()"
     ])
     
     return Popen([sys.executable, '-c', cmd, '--existing', cf] + argv,
         stdout=PIPE, stderr=PIPE, close_fds=(sys.platform != 'win32'),
     )
 
 
 def tunnel_to_kernel(connection_info, sshserver, sshkey=None):
     """tunnel connections to a kernel via ssh
     
     This will open four SSH tunnels from localhost on this machine to the
     ports associated with the kernel.  They can be either direct
     localhost-localhost tunnels, or if an intermediate server is necessary,
     the kernel must be listening on a public IP.
     
     Parameters
     ----------
     connection_info : dict or str (path)
         Either a connection dict, or the path to a JSON connection file
     sshserver : str
         The ssh sever to use to tunnel to the kernel. Can be a full
         `user@server:port` string. ssh config aliases are respected.
     sshkey : str [optional]
         Path to file containing ssh key to use for authentication.
         Only necessary if your ssh config does not already associate
         a keyfile with the host.
     
     Returns
     -------
     
     (shell, iopub, stdin, hb) : ints
         The four ports on localhost that have been forwarded to the kernel.
     """
     if isinstance(connection_info, string_types):
         # it's a path, unpack it
         with open(connection_info) as f:
             connection_info = json.loads(f.read())
     
     cf = connection_info
     
     lports = tunnel.select_random_ports(4)
     rports = cf['shell_port'], cf['iopub_port'], cf['stdin_port'], cf['hb_port']
     
     remote_ip = cf['ip']
     
     if tunnel.try_passwordless_ssh(sshserver, sshkey):
         password=False
     else:
         password = getpass("SSH Password for %s: " % cast_bytes_py2(sshserver))
     
     for lp,rp in zip(lports, rports):
         tunnel.ssh_tunnel(lp, rp, sshserver, remote_ip, sshkey, password)
     
     return tuple(lports)
 
 
 #-----------------------------------------------------------------------------
 # Mixin for classes that work with connection files
 #-----------------------------------------------------------------------------
 
 channel_socket_types = {
     'hb' : zmq.REQ,
     'shell' : zmq.DEALER,
     'iopub' : zmq.SUB,
     'stdin' : zmq.DEALER,
     'control': zmq.DEALER,
 }
 
 port_names = [ "%s_port" % channel for channel in ('shell', 'stdin', 'iopub', 'hb', 'control')]
 
 class ConnectionFileMixin(Configurable):
     """Mixin for configurable classes that work with connection files"""
 
     # The addresses for the communication channels
-    connection_file = Unicode('')
+    connection_file = Unicode('', config=True, 
+    help="""JSON file in which to store connection info [default: kernel-<pid>.json]
+    
+    This file will contain the IP, ports, and authentication key needed to connect
+    clients to this kernel. By default, this file will be created in the security dir
+    of the current profile, but can be specified by absolute path.
+    """)
     _connection_file_written = Bool(False)
 
     transport = CaselessStrEnum(['tcp', 'ipc'], default_value='tcp', config=True)
 
     ip = Unicode(config=True,
         help="""Set the kernel\'s IP address [default localhost].
         If the IP address is something other than localhost, then
         Consoles on other machines will be able to connect
         to the Kernel, so be careful!"""
     )
 
     def _ip_default(self):
         if self.transport == 'ipc':
             if self.connection_file:
                 return os.path.splitext(self.connection_file)[0] + '-ipc'
             else:
                 return 'kernel-ipc'
         else:
             return localhost()
 
     def _ip_changed(self, name, old, new):
         if new == '*':
             self.ip = '0.0.0.0'
 
     # protected traits
 
-    shell_port = Integer(0)
-    iopub_port = Integer(0)
-    stdin_port = Integer(0)
-    control_port = Integer(0)
-    hb_port = Integer(0)
+    hb_port = Integer(0, config=True,
+            help="set the heartbeat port [default: random]")
+    shell_port = Integer(0, config=True,
+            help="set the shell (ROUTER) port [default: random]")
+    iopub_port = Integer(0, config=True,
+            help="set the iopub (PUB) port [default: random]")
+    stdin_port = Integer(0, config=True,
+            help="set the stdin (ROUTER) port [default: random]")
+    control_port = Integer(0, config=True,
+            help="set the control (ROUTER) port [default: random]")
 
     @property
     def ports(self):
         return [ getattr(self, name) for name in port_names ]
 
     #--------------------------------------------------------------------------
     # Connection and ipc file management
     #--------------------------------------------------------------------------
 
     def get_connection_info(self):
         """return the connection info as a dict"""
         return dict(
             transport=self.transport,
             ip=self.ip,
             shell_port=self.shell_port,
             iopub_port=self.iopub_port,
             stdin_port=self.stdin_port,
             hb_port=self.hb_port,
             control_port=self.control_port,
             signature_scheme=self.session.signature_scheme,
             key=self.session.key,
         )
 
     def cleanup_connection_file(self):
         """Cleanup connection file *if we wrote it*
 
         Will not raise if the connection file was already removed somehow.
         """
         if self._connection_file_written:
             # cleanup connection files on full shutdown of kernel we started
             self._connection_file_written = False
             try:
                 os.remove(self.connection_file)
             except (IOError, OSError, AttributeError):
                 pass
 
     def cleanup_ipc_files(self):
         """Cleanup ipc files if we wrote them."""
         if self.transport != 'ipc':
             return
         for port in self.ports:
             ipcfile = "%s-%i" % (self.ip, port)
             try:
                 os.remove(ipcfile)
             except (IOError, OSError):
                 pass
 
     def write_connection_file(self):
         """Write connection info to JSON dict in self.connection_file."""
         if self._connection_file_written and os.path.exists(self.connection_file):
             return
 
         self.connection_file, cfg = write_connection_file(self.connection_file,
             transport=self.transport, ip=self.ip, key=self.session.key,
             stdin_port=self.stdin_port, iopub_port=self.iopub_port,
             shell_port=self.shell_port, hb_port=self.hb_port,
             control_port=self.control_port,
             signature_scheme=self.session.signature_scheme,
         )
         # write_connection_file also sets default ports:
         for name in port_names:
             setattr(self, name, cfg[name])
 
         self._connection_file_written = True
 
     def load_connection_file(self):
         """Load connection info from JSON dict in self.connection_file."""
+        self.log.debug(u"Loading connection file %s", self.connection_file)
         with open(self.connection_file) as f:
-            cfg = json.loads(f.read())
+            cfg = json.load(f)
+        self.transport = cfg.get('transport', self.transport)
+        self.ip = cfg.get('ip', self._ip_default())
 
-        self.transport = cfg.get('transport', 'tcp')
-        self.ip = cfg['ip']
         for name in port_names:
+            if getattr(self, name) == 0 and name in cfg:
+                # not overridden by config or cl_args
             setattr(self, name, cfg[name])
         if 'key' in cfg:
-            self.session.key = str_to_bytes(cfg['key'])
-        if cfg.get('signature_scheme'):
-            self.session.signature_scheme = cfg['signature_scheme']
-
+            self.config.Session.key = str_to_bytes(cfg['key'])
+        if 'signature_scheme' in cfg:
+            self.config.Session.signature_scheme = cfg['signature_scheme']
     #--------------------------------------------------------------------------
     # Creating connected sockets
     #--------------------------------------------------------------------------
 
     def _make_url(self, channel):
         """Make a ZeroMQ URL for a given channel."""
         transport = self.transport
         ip = self.ip
         port = getattr(self, '%s_port' % channel)
 
         if transport == 'tcp':
             return "tcp://%s:%i" % (ip, port)
         else:
             return "%s://%s-%s" % (transport, ip, port)
 
     def _create_connected_socket(self, channel, identity=None):
         """Create a zmq Socket and connect it to the kernel."""
         url = self._make_url(channel)
         socket_type = channel_socket_types[channel]
         self.log.debug("Connecting to: %s" % url)
         sock = self.context.socket(socket_type)
         if identity:
             sock.identity = identity
         sock.connect(url)
         return sock
 
     def connect_iopub(self, identity=None):
         """return zmq Socket connected to the IOPub channel"""
         sock = self._create_connected_socket('iopub', identity=identity)
         sock.setsockopt(zmq.SUBSCRIBE, b'')
         return sock
 
     def connect_shell(self, identity=None):
         """return zmq Socket connected to the Shell channel"""
         return self._create_connected_socket('shell', identity=identity)
 
     def connect_stdin(self, identity=None):
         """return zmq Socket connected to the StdIn channel"""
         return self._create_connected_socket('stdin', identity=identity)
 
     def connect_hb(self, identity=None):
         """return zmq Socket connected to the Heartbeat channel"""
         return self._create_connected_socket('hb', identity=identity)
 
     def connect_control(self, identity=None):
         """return zmq Socket connected to the Heartbeat channel"""
         return self._create_connected_socket('control', identity=identity)
 
 
 __all__ = [
     'write_connection_file',
     'get_connection_file',
     'find_connection_file',
     'get_connection_info',
     'connect_qtconsole',
     'tunnel_to_kernel',
 ]

IPython/kernel/zmq/kernelapp.py

@@ -1,473 +1,411 b''
 """An Application for launching a kernel
-
-Authors
--------
-* MinRK
 """
-#-----------------------------------------------------------------------------
-#  Copyright (C) 2011  The IPython Development Team
-#
-#  Distributed under the terms of the BSD License.  The full license is in
-#  the file COPYING.txt, distributed as part of this software.
-#-----------------------------------------------------------------------------
+# Copyright (c) IPython Development Team.
+# Distributed under the terms of the Modified BSD License.
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 from __future__ import print_function
 
 # Standard library imports
 import atexit
-import json
 import os
 import sys
 import signal
 
 # System library imports
 import zmq
 from zmq.eventloop import ioloop
 from zmq.eventloop.zmqstream import ZMQStream
 
 # IPython imports
 from IPython.core.ultratb import FormattedTB
 from IPython.core.application import (
     BaseIPythonApplication, base_flags, base_aliases, catch_config_error
 )
 from IPython.core.profiledir import ProfileDir
 from IPython.core.shellapp import (
     InteractiveShellApp, shell_flags, shell_aliases
 )
 from IPython.utils import io
-from IPython.utils.localinterfaces import localhost
 from IPython.utils.path import filefind
-from IPython.utils.py3compat import str_to_bytes
 from IPython.utils.traitlets import (
-    Any, Instance, Dict, Unicode, Integer, Bool, CaselessStrEnum,
-    DottedObjectName,
+    Any, Instance, Dict, Unicode, Integer, Bool, DottedObjectName,
 )
 from IPython.utils.importstring import import_item
 from IPython.kernel import write_connection_file
+from IPython.kernel.connect import ConnectionFileMixin
 
 # local imports
 from .heartbeat import Heartbeat
 from .ipkernel import Kernel
 from .parentpoller import ParentPollerUnix, ParentPollerWindows
 from .session import (
     Session, session_flags, session_aliases, default_secure,
 )
 from .zmqshell import ZMQInteractiveShell
 
 #-----------------------------------------------------------------------------
 # Flags and Aliases
 #-----------------------------------------------------------------------------
 
 kernel_aliases = dict(base_aliases)
 kernel_aliases.update({
     'ip' : 'IPKernelApp.ip',
     'hb' : 'IPKernelApp.hb_port',
     'shell' : 'IPKernelApp.shell_port',
     'iopub' : 'IPKernelApp.iopub_port',
     'stdin' : 'IPKernelApp.stdin_port',
     'control' : 'IPKernelApp.control_port',
     'f' : 'IPKernelApp.connection_file',
     'parent': 'IPKernelApp.parent_handle',
     'transport': 'IPKernelApp.transport',
 })
 if sys.platform.startswith('win'):
     kernel_aliases['interrupt'] = 'IPKernelApp.interrupt'
 
 kernel_flags = dict(base_flags)
 kernel_flags.update({
     'no-stdout' : (
             {'IPKernelApp' : {'no_stdout' : True}},
             "redirect stdout to the null device"),
     'no-stderr' : (
             {'IPKernelApp' : {'no_stderr' : True}},
             "redirect stderr to the null device"),
     'pylab' : (
         {'IPKernelApp' : {'pylab' : 'auto'}},
         """Pre-load matplotlib and numpy for interactive use with
         the default matplotlib backend."""),
 })
 
 # inherit flags&aliases for any IPython shell apps
 kernel_aliases.update(shell_aliases)
 kernel_flags.update(shell_flags)
 
 # inherit flags&aliases for Sessions
 kernel_aliases.update(session_aliases)
 kernel_flags.update(session_flags)
 
 _ctrl_c_message = """\
 NOTE: When using the `ipython kernel` entry point, Ctrl-C will not work.
 
 To exit, you will have to explicitly quit this process, by either sending
 "quit" from a client, or using Ctrl-\\ in UNIX-like environments.
 
 To read more about this, see https://github.com/ipython/ipython/issues/2049
 
 """
 
 #-----------------------------------------------------------------------------
 # Application class for starting an IPython Kernel
 #-----------------------------------------------------------------------------
 
-class IPKernelApp(BaseIPythonApplication, InteractiveShellApp):
+class IPKernelApp(BaseIPythonApplication, InteractiveShellApp,
+        ConnectionFileMixin):
     name='ipkernel'
     aliases = Dict(kernel_aliases)
     flags = Dict(kernel_flags)
     classes = [Kernel, ZMQInteractiveShell, ProfileDir, Session]
     # the kernel class, as an importstring
     kernel_class = DottedObjectName('IPython.kernel.zmq.ipkernel.Kernel', config=True,
     help="""The Kernel subclass to be used.
     
     This should allow easy re-use of the IPKernelApp entry point
     to configure and launch kernels other than IPython's own.
     """)
     kernel = Any()
     poller = Any() # don't restrict this even though current pollers are all Threads
     heartbeat = Instance(Heartbeat)
     session = Instance('IPython.kernel.zmq.session.Session')
     ports = Dict()
     
     # ipkernel doesn't get its own config file
     def _config_file_name_default(self):
         return 'ipython_config.py'
     
     # inherit config file name from parent:
     parent_appname = Unicode(config=True)
     def _parent_appname_changed(self, name, old, new):
         if self.config_file_specified:
             # it was manually specified, ignore
             return
         self.config_file_name = new.replace('-','_') + u'_config.py'
         # don't let this count as specifying the config file
         self.config_file_specified.remove(self.config_file_name)
         
     # connection info:
-    transport = CaselessStrEnum(['tcp', 'ipc'], default_value='tcp', config=True)
-    ip = Unicode(config=True,
-        help="Set the IP or interface on which the kernel will listen.")
-    def _ip_default(self):
-        if self.transport == 'ipc':
-            if self.connection_file:
-                return os.path.splitext(self.abs_connection_file)[0] + '-ipc'
-            else:
-                return 'kernel-ipc'
-        else:
-            return localhost()
-    
-    hb_port = Integer(0, config=True, help="set the heartbeat port [default: random]")
-    shell_port = Integer(0, config=True, help="set the shell (ROUTER) port [default: random]")
-    iopub_port = Integer(0, config=True, help="set the iopub (PUB) port [default: random]")
-    stdin_port = Integer(0, config=True, help="set the stdin (ROUTER) port [default: random]")
-    control_port = Integer(0, config=True, help="set the control (ROUTER) port [default: random]")
-    connection_file = Unicode('', config=True, 
-    help="""JSON file in which to store connection info [default: kernel-<pid>.json]
-    
-    This file will contain the IP, ports, and authentication key needed to connect
-    clients to this kernel. By default, this file will be created in the security dir
-    of the current profile, but can be specified by absolute path.
-    """)
+    
     @property
     def abs_connection_file(self):
         if os.path.basename(self.connection_file) == self.connection_file:
             return os.path.join(self.profile_dir.security_dir, self.connection_file)
         else:
             return self.connection_file
         
 
     # streams, etc.
     no_stdout = Bool(False, config=True, help="redirect stdout to the null device")
     no_stderr = Bool(False, config=True, help="redirect stderr to the null device")
     outstream_class = DottedObjectName('IPython.kernel.zmq.iostream.OutStream',
         config=True, help="The importstring for the OutStream factory")
     displayhook_class = DottedObjectName('IPython.kernel.zmq.displayhook.ZMQDisplayHook',
         config=True, help="The importstring for the DisplayHook factory")
 
     # polling
     parent_handle = Integer(0, config=True,
         help="""kill this process if its parent dies.  On Windows, the argument
         specifies the HANDLE of the parent process, otherwise it is simply boolean.
         """)
     interrupt = Integer(0, config=True,
         help="""ONLY USED ON WINDOWS
         Interrupt this process when the parent is signaled.
         """)
 
     def init_crash_handler(self):
         # Install minimal exception handling
         sys.excepthook = FormattedTB(mode='Verbose', color_scheme='NoColor',
                                      ostream=sys.__stdout__)
 
     def init_poller(self):
         if sys.platform == 'win32':
             if self.interrupt or self.parent_handle:
                 self.poller = ParentPollerWindows(self.interrupt, self.parent_handle)
         elif self.parent_handle:
             self.poller = ParentPollerUnix()
 
     def _bind_socket(self, s, port):
         iface = '%s://%s' % (self.transport, self.ip)
         if self.transport == 'tcp':
             if port <= 0:
                 port = s.bind_to_random_port(iface)
             else:
                 s.bind("tcp://%s:%i" % (self.ip, port))
         elif self.transport == 'ipc':
             if port <= 0:
                 port = 1
                 path = "%s-%i" % (self.ip, port)
                 while os.path.exists(path):
                     port = port + 1
                     path = "%s-%i" % (self.ip, port)
             else:
                 path = "%s-%i" % (self.ip, port)
             s.bind("ipc://%s" % path)
         return port
 
-    def load_connection_file(self):
-        """load ip/port/hmac config from JSON connection file"""
-        try:
-            fname = filefind(self.connection_file, ['.', self.profile_dir.security_dir])
-        except IOError:
-            self.log.debug("Connection file not found: %s", self.connection_file)
-            # This means I own it, so I will clean it up:
-            atexit.register(self.cleanup_connection_file)
-            return
-        self.log.debug(u"Loading connection file %s", fname)
-        with open(fname) as f:
-            s = f.read()
-        cfg = json.loads(s)
-        self.transport = cfg.get('transport', self.transport)
-        if self.ip == self._ip_default() and 'ip' in cfg:
-            # not overridden by config or cl_args
-            self.ip = cfg['ip']
-        for channel in ('hb', 'shell', 'iopub', 'stdin', 'control'):
-            name = channel + '_port'
-            if getattr(self, name) == 0 and name in cfg:
-                # not overridden by config or cl_args
-                setattr(self, name, cfg[name])
-        if 'key' in cfg:
-            self.config.Session.key = str_to_bytes(cfg['key'])
-    
     def write_connection_file(self):
         """write connection info to JSON file"""
         cf = self.abs_connection_file
         self.log.debug("Writing connection file: %s", cf)
         write_connection_file(cf, ip=self.ip, key=self.session.key, transport=self.transport,
         shell_port=self.shell_port, stdin_port=self.stdin_port, hb_port=self.hb_port,
         iopub_port=self.iopub_port, control_port=self.control_port)
     
     def cleanup_connection_file(self):
         cf = self.abs_connection_file
         self.log.debug("Cleaning up connection file: %s", cf)
         try:
             os.remove(cf)
         except (IOError, OSError):
             pass
         
         self.cleanup_ipc_files()
     
-    def cleanup_ipc_files(self):
-        """cleanup ipc files if we wrote them"""
-        if self.transport != 'ipc':
-            return
-        for port in (self.shell_port, self.iopub_port, self.stdin_port, self.hb_port, self.control_port):
-            ipcfile = "%s-%i" % (self.ip, port)
-            try:
-                os.remove(ipcfile)
-            except (IOError, OSError):
-                pass
-    
     def init_connection_file(self):
         if not self.connection_file:
             self.connection_file = "kernel-%s.json"%os.getpid()
         try:
+            self.connection_file = filefind(self.connection_file, ['.', self.profile_dir.security_dir])
+        except IOError:
+            self.log.debug("Connection file not found: %s", self.connection_file)
+            # This means I own it, so I will clean it up:
+            atexit.register(self.cleanup_connection_file)
+            return
+        try:
             self.load_connection_file()
         except Exception:
             self.log.error("Failed to load connection file: %r", self.connection_file, exc_info=True)
             self.exit(1)
     
     def init_sockets(self):
         # Create a context, a session, and the kernel sockets.
         self.log.info("Starting the kernel at pid: %i", os.getpid())
         context = zmq.Context.instance()
         # Uncomment this to try closing the context.
         # atexit.register(context.term)
 
         self.shell_socket = context.socket(zmq.ROUTER)
         self.shell_port = self._bind_socket(self.shell_socket, self.shell_port)
         self.log.debug("shell ROUTER Channel on port: %i" % self.shell_port)
 
         self.iopub_socket = context.socket(zmq.PUB)
         self.iopub_port = self._bind_socket(self.iopub_socket, self.iopub_port)
         self.log.debug("iopub PUB Channel on port: %i" % self.iopub_port)
 
         self.stdin_socket = context.socket(zmq.ROUTER)
         self.stdin_port = self._bind_socket(self.stdin_socket, self.stdin_port)
         self.log.debug("stdin ROUTER Channel on port: %i" % self.stdin_port)
 
         self.control_socket = context.socket(zmq.ROUTER)
         self.control_port = self._bind_socket(self.control_socket, self.control_port)
         self.log.debug("control ROUTER Channel on port: %i" % self.control_port)
     
     def init_heartbeat(self):
         """start the heart beating"""
         # heartbeat doesn't share context, because it mustn't be blocked
         # by the GIL, which is accessed by libzmq when freeing zero-copy messages
         hb_ctx = zmq.Context()
         self.heartbeat = Heartbeat(hb_ctx, (self.transport, self.ip, self.hb_port))
         self.hb_port = self.heartbeat.port
         self.log.debug("Heartbeat REP Channel on port: %i" % self.hb_port)
         self.heartbeat.start()
     
     def log_connection_info(self):
         """display connection info, and store ports"""
         basename = os.path.basename(self.connection_file)
         if basename == self.connection_file or \
             os.path.dirname(self.connection_file) == self.profile_dir.security_dir:
             # use shortname
             tail = basename
             if self.profile != 'default':
                 tail += " --profile %s" % self.profile
         else:
             tail = self.connection_file
         lines = [
             "To connect another client to this kernel, use:",
             "    --existing %s" % tail,
         ]
         # log connection info
         # info-level, so often not shown.
         # frontends should use the %connect_info magic
         # to see the connection info
         for line in lines:
             self.log.info(line)
         # also raw print to the terminal if no parent_handle (`ipython kernel`)
         if not self.parent_handle:
             io.rprint(_ctrl_c_message)
             for line in lines:
                 io.rprint(line)
 
         self.ports = dict(shell=self.shell_port, iopub=self.iopub_port,
                                 stdin=self.stdin_port, hb=self.hb_port,
                                 control=self.control_port)
 
     def init_session(self):
         """create our session object"""
         default_secure(self.config)
         self.session = Session(parent=self, username=u'kernel')
 
     def init_blackhole(self):
         """redirects stdout/stderr to devnull if necessary"""
         if self.no_stdout or self.no_stderr:
             blackhole = open(os.devnull, 'w')
             if self.no_stdout:
                 sys.stdout = sys.__stdout__ = blackhole
             if self.no_stderr:
                 sys.stderr = sys.__stderr__ = blackhole
     
     def init_io(self):
         """Redirect input streams and set a display hook."""
         if self.outstream_class:
             outstream_factory = import_item(str(self.outstream_class))
             sys.stdout = outstream_factory(self.session, self.iopub_socket, u'stdout')
             sys.stderr = outstream_factory(self.session, self.iopub_socket, u'stderr')
         if self.displayhook_class:
             displayhook_factory = import_item(str(self.displayhook_class))
             sys.displayhook = displayhook_factory(self.session, self.iopub_socket)
 
     def init_signal(self):
         signal.signal(signal.SIGINT, signal.SIG_IGN)
 
     def init_kernel(self):
         """Create the Kernel object itself"""
         shell_stream = ZMQStream(self.shell_socket)
         control_stream = ZMQStream(self.control_socket)
         
         kernel_factory = import_item(str(self.kernel_class))
 
         kernel = kernel_factory(parent=self, session=self.session,
                                 shell_streams=[shell_stream, control_stream],
                                 iopub_socket=self.iopub_socket,
                                 stdin_socket=self.stdin_socket,
                                 log=self.log,
                                 profile_dir=self.profile_dir,
                                 user_ns=self.user_ns,
         )
         kernel.record_ports(self.ports)
         self.kernel = kernel
 
     def init_gui_pylab(self):
         """Enable GUI event loop integration, taking pylab into account."""
 
         # Provide a wrapper for :meth:`InteractiveShellApp.init_gui_pylab`
         # to ensure that any exception is printed straight to stderr.
         # Normally _showtraceback associates the reply with an execution,
         # which means frontends will never draw it, as this exception
         # is not associated with any execute request.
 
         shell = self.shell
         _showtraceback = shell._showtraceback
         try:
             # replace pyerr-sending traceback with stderr
             def print_tb(etype, evalue, stb):
                 print ("GUI event loop or pylab initialization failed",
                        file=io.stderr)
                 print (shell.InteractiveTB.stb2text(stb), file=io.stderr)
             shell._showtraceback = print_tb
             InteractiveShellApp.init_gui_pylab(self)
         finally:
             shell._showtraceback = _showtraceback
 
     def init_shell(self):
         self.shell = self.kernel.shell
         self.shell.configurables.append(self)
 
     @catch_config_error
     def initialize(self, argv=None):
         super(IPKernelApp, self).initialize(argv)
         self.init_blackhole()
         self.init_connection_file()
         self.init_session()
         self.init_poller()
         self.init_sockets()
         self.init_heartbeat()
         # writing/displaying connection info must be *after* init_sockets/heartbeat
         self.log_connection_info()
         self.write_connection_file()
         self.init_io()
         self.init_signal()
         self.init_kernel()
         # shell init steps
         self.init_path()
         self.init_shell()
         self.init_gui_pylab()
         self.init_extensions()
         self.init_code()
         # flush stdout/stderr, so that anything written to these streams during
         # initialization do not get associated with the first execution request
         sys.stdout.flush()
         sys.stderr.flush()
 
     def start(self):
         if self.poller is not None:
             self.poller.start()
         self.kernel.start()
         try:
             ioloop.IOLoop.instance().start()
         except KeyboardInterrupt:
             pass
 
 launch_new_instance = IPKernelApp.launch_instance
 
 def main():
     """Run an IPKernel as an application"""
     app = IPKernelApp.instance()
     app.initialize()
     app.start()
 
 
 if __name__ == '__main__':
     main()