Fix SSH connectivity issues.

- increase SSH connection attempts number to 60 (5 minutes)
- avoiding using host heys to prevent connection failures

Change-Id: I10babbbd650d9a595b7c5361886da7ad0f3df2a0

tobiko/shell/ssh/_client.py

@@ -292,8 +292,7 @@ def ssh_connect(hostname, username=None, port=None, connection_interval=None,
                 connection_attempts=None, proxy_command=None,
                 proxy_client=None, **parameters):
     client = paramiko.SSHClient()
-    client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
-    client.load_system_host_keys()
+    client.set_missing_host_key_policy(paramiko.WarningPolicy())
 
     login = _command.ssh_login(hostname=hostname, username=username, port=port)
     attempts = connection_attempts or 1
@@ -317,7 +316,8 @@ def ssh_connect(hostname, username=None, port=None, connection_interval=None,
             if attempt >= attempts:
                 raise
 
-            LOG.debug("Error logging in to %r: \n(%s)", login, ex)
+            LOG.debug("Error logging in to %r: \n(%s)", login, ex,
+                      exc_info=1)
             sleep_time = start_time + interval - time.time()
             if sleep_time > 0.:
                 LOG.debug("Retrying connecting to %r in %d seconds...", login,

tobiko/shell/ssh/config.py

@@ -52,7 +52,7 @@ def register_tobiko_options(conf):
                            default=5.,
                            help="SSH connect timeout in seconds"),
               cfg.IntOpt('connection_attempts',
-                         default=24,
+                         default=60,
                          help=("Incremental seconds to wait after every "
                                "failed SSH connection attempt")),
               cfg.FloatOpt('connection_interval',