ssh: Support disabling strict host key checking.

mitogen/ssh.py

@@ -16,20 +16,28 @@ class Stream(mitogen.master.Stream):
     port = None
 
     def construct(self, hostname, username=None, ssh_path=None, port=None,
-                 **kwargs):
+                  check_host_keys=True, **kwargs):
         super(Stream, self).construct(**kwargs)
         self.hostname = hostname
         self.username = username
         self.port = port
+        self.check_host_keys = check_host_keys
         if ssh_path:
             self.ssh_path = ssh_path
 
     def get_boot_command(self):
         bits = [self.ssh_path]
+        bits += ['-o', 'BatchMode yes']
+
         if self.username:
             bits += ['-l', self.username]
         if self.port is not None:
             bits += ['-p', str(self.port)]
+        if not self.check_host_keys:
+            bits += [
+                '-o', 'StrictHostKeyChecking no',
+                '-o', 'UserKnownHostsFile /dev/null',
+            ]
         bits.append(self.hostname)
         base = super(Stream, self).get_boot_command()
         return bits + map(commands.mkarg, base)