Improve ssh concurrency on websocket

ssh module was pausing input for the
entire websocket while doing the simple 'write' operation.

Change to background the actual
logon processing,
rather than blocking what should be a fairly trivial write operation.

confluent_server/confluent/plugins/shell/ssh.py

@@ -120,6 +120,10 @@ class SshShell(conapi.Console):
         return
 
     def logon(self):
+        self.inputmode = -3
+        eventlet.spawn_n(self.do_logon)
+    
+    def do_logon(self):
         self.ssh = paramiko.SSHClient()
         self.ssh.set_missing_host_key_policy(
                 HostKeyHandler(self.nodeconfig, self.node))
@@ -186,6 +190,8 @@ class SshShell(conapi.Console):
         if self.inputmode == -2:
             self.datacallback(conapi.ConsoleEvent.Disconnect)
             return
+        elif self.inputmode == -3:
+            return
         elif self.inputmode == -1:
             while len(data) and data[0:1] == b'\x7f' and len(self.keyaction):
                 self.datacallback('\b \b')  # erase previously echoed value