plugin manhole: manhole debug plugin, first draft:

this plugin open a telnet server which open a Python interpreter and allows to inspect the backend while it is running.
To enable it, the settings "manhole_debug_dangerous_port_int" must be set to the desired TCP port in [DEFAULT] section of sat.conf.
A warning will be logged if the server is enabled.

Currently only a telnet server is available, and no login is required. This may change in the futur to enable login/password and ssh access, or even an XMPP access.
This is a debugging feature and must only be used during development.
Once in the Python interpreter, the "host" variable is accessible.

sat/plugins/plugin_dbg_manhole.py

@@ -0,0 +1,65 @@
+#!/usr/bin/env python2
+# -*- coding: utf-8 -*-
+
+# SAT plugin for debugging, using a manhole
+# Copyright (C) 2009-2019 Jérôme Poisson (goffi@goffi.org)
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+from sat.core.i18n import _
+from sat.core.constants import Const as C
+from sat.core.log import getLogger
+from twisted.conch.insults import insults
+from twisted.conch.telnet import TelnetTransport, TelnetBootstrapProtocol
+from twisted.internet import reactor, protocol
+from twisted.conch.manhole import ColoredManhole
+
+log = getLogger(__name__)
+
+PLUGIN_INFO = {
+    C.PI_NAME: u"Manhole debug plugin",
+    C.PI_IMPORT_NAME: u"manhole",
+    C.PI_TYPE: u"DEBUG",
+    C.PI_PROTOCOLS: [],
+    C.PI_DEPENDENCIES: [],
+    C.PI_MAIN: u"Manhole",
+    C.PI_HANDLER: u"no",
+    C.PI_DESCRIPTION: _(u"""Debug plugin to have a telnet server"""),
+}
+
+
+
+class Manhole(object):
+
+    def __init__(self, host):
+        self.host = host
+        port = int(host.memory.getConfig(None, "manhole_debug_dangerous_port_int"))
+        if port:
+            self.startManhole(port)
+
+    def startManhole(self, port):
+        log.warning(_(u"/!\\ Manhole debug server activated, be sure to not use it in "
+                      u"production, this is dangerous /!\\"))
+        log.info(_(u"You can connect to manhole server using telnet on port {port}")
+            .format(port=port))
+        f = protocol.ServerFactory()
+        namespace = {
+            u"host": self.host,
+        }
+        f.protocol = lambda: TelnetTransport(TelnetBootstrapProtocol,
+                                             insults.ServerProtocol,
+                                             ColoredManhole,
+                                             namespace=namespace,
+                                             )
+        reactor.listenTCP(port, f)