Cleanly handle stop/restart when not running

Previously some rather uncomfortable looking output would be emitted at someone trying to restart
confluent if not running.  Be nicer and recognize when service is not running and a stop attempt is made.

confluent_server/confluent/sockapi.py

@@ -19,6 +19,7 @@
 # It implement unix and tls sockets
 # 
 
+import atexit
 import os
 import pwd
 import stat
@@ -222,6 +223,11 @@ def _tlsstartup(cnn):
                           server_side=True)
     sessionhdl(cnn, authname)
 
+def removesocket():
+    try:
+        os.remove("/var/run/confluent/api.sock")
+    except OSError:
+        pass
 
 def _unixdomainhandler():
     unixsocket = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
@@ -233,6 +239,7 @@ def _unixdomainhandler():
     os.chmod("/var/run/confluent/api.sock",
              stat.S_IWOTH | stat.S_IROTH | stat.S_IWGRP |
              stat.S_IRGRP | stat.S_IWUSR | stat.S_IRUSR)
+    atexit.register(removesocket)
     unixsocket.listen(5)
     while True:
         cnn, addr = unixsocket.accept()

confluent_server/sysvinit/confluent

@@ -21,8 +21,10 @@ fi
 
 case $1 in
 	restart)
-		echo -n 'Stopping Confluent '
-		/opt/confluent/bin/confetty shutdown /
+	    if [ -S /var/run/confluent/api.sock ]; then
+		    echo -n 'Stopping Confluent '
+		    /opt/confluent/bin/confetty shutdown /
+		fi
 		echo -n 'Starting Confluent '
 		/opt/confluent/bin/confluent
 		$LOG_SUCCESS
@@ -34,7 +36,9 @@ case $1 in
 		;;
 	stop)
 		echo -n 'Stopping Confluent '
-		/opt/confluent/bin/confetty shutdown /
+		if [ -S /var/run/confluent/api.sock ]; then
+		    /opt/confluent/bin/confetty shutdown /
+		fi
 		$LOG_SUCCESS
 		;;
 esac