Only activate the remote API socket if user makes cert

This prevents the useless networking socket from being opened
when it cannot be used.  This means most implementations will not
have an extra port to explain unless the user goes through the work
and knows what it would be.

confluent_server/confluent/sockapi.py

@@ -21,6 +21,8 @@
 #
 
 import atexit
+import ctypes
+import ctypes.util
 import errno
 import os
 import pwd
@@ -29,6 +31,7 @@ import struct
 import sys
 import traceback
 
+import eventlet.green.select as select
 import eventlet.green.socket as socket
 import eventlet.green.ssl as ssl
 import eventlet
@@ -54,6 +57,7 @@ except AttributeError:
     else:
         SO_PEERCRED = 17
 
+plainsocket = None
 
 class ClientConsole(object):
     def __init__(self, client):
@@ -252,6 +256,7 @@ def start_term(authname, cfm, connection, params, path, authdata, skipauth):
 
 
 def _tlshandler(bind_host, bind_port):
+    global plainsocket
     plainsocket = socket.socket(socket.AF_INET6)
     plainsocket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
     plainsocket.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
@@ -336,6 +341,36 @@ class SockApi(object):
         global tracelog
         tracelog = log.Logger('trace')
         auditlog = log.Logger('audit')
+        self.tlsserver = None
+        if self.should_run_remoteapi():
+            self.start_remoteapi()
+        else:
+            eventlet.spawn_n(self.watch_for_cert)
+        self.unixdomainserver = eventlet.spawn(_unixdomainhandler)
+
+    def watch_for_cert(self):
+        libc = ctypes.CDLL(ctypes.util.find_library('c'))
+        watcher = libc.inotify_init()
+        if libc.inotify_add_watch(watcher, '/etc/confluent/', 0x100) > -1:
+            while True:
+                select.select((watcher,), (), (), 86400)
+                if self.should_run_remoteapi():
+                    os.close(watcher)
+                    self.start_remoteapi()
+                    break
+
+    def should_run_remoteapi(self):
+        return os.path.exists("/etc/confluent/srvcert.pem")
+
+    def stop_remoteapi(self):
+        if self.tlsserver is None:
+            return
+        self.tlsserver.kill()
+        plainsocket.close()
+        self.tlsserver = None
+
+    def start_remoteapi(self):
+        if self.tlsserver is not None:
+            return
         self.tlsserver = eventlet.spawn(
             _tlshandler, self.bind_host, self.bind_port)
-        self.unixdomainserver = eventlet.spawn(_unixdomainhandler)