Allow disabling host-key-checking in statemachine

The statemachine driver was ignoring the host-key-checking option.
Correct that by passing it in as a parameter to the keyscan function.

Additionally, the Azure driver had a typo which initialized the
the value for host-key-checking to the wrong value.  Correct that.

Change-Id: Ie4a6b5e960b0a4906421924435b768ae545a2057

nodepool/driver/azure/config.py

@@ -218,7 +218,7 @@ class AzurePool(ConfigPool):
         self.use_internal_ip = pool_config.get(
             'use-internal-ip', self.provider.use_internal_ip)
         self.host_key_checking = pool_config.get(
-            'host-key-checking', self.provider.use_internal_ip)
+            'host-key-checking', self.provider.host_key_checking)
 
     @staticmethod
     def getSchema():

nodepool/driver/metastatic/adapter.py

@@ -122,6 +122,7 @@ class MetastaticInstance(statemachine.Instance):
             self.shell_type = backing_node.shell_type
             self.connection_port = backing_node.connection_port
             self.connection_type = backing_node.connection_type
+            self.host_keys = backing_node.host_keys
             backing_node_id = backing_node.id
         else:
             backing_node_id = None

nodepool/driver/metastatic/config.py

@@ -73,6 +73,8 @@ class MetastaticPool(ConfigPool):
         self.labels = {}
         # We will just use the interface_ip of the backing node
         self.use_internal_ip = False
+        self.host_key_checking = False
+
         self.load(pool_config)
 
     def load(self, pool_config):

nodepool/driver/statemachine.py

@@ -32,7 +32,7 @@ from kazoo import exceptions as kze
 import cachetools
 
 
-def keyscan(node_id, interface_ip,
+def keyscan(host_key_checking, node_id, interface_ip,
             connection_type, connection_port,
             timeout):
     """A standalone function for scanning keys to pass to a thread/process
@@ -40,6 +40,8 @@ def keyscan(node_id, interface_ip,
     """
 
     keys = []
+    if not host_key_checking:
+        return keys
     try:
         if (connection_type == 'ssh' or
             connection_type == 'network_cli'):
@@ -156,7 +158,8 @@ class StateMachineNodeLauncher(stats.StatsReporter):
         # Optionally, if the node has updated values that we set from
         # the image attributes earlier, set those.
         for attr in ('username', 'python_path', 'shell_type',
-                     'connection_port', 'connection_type'):
+                     'connection_port', 'connection_type',
+                     'host_keys'):
             if hasattr(instance, attr):
                 setattr(node, attr, getattr(instance, attr))
 
@@ -175,7 +178,8 @@ class StateMachineNodeLauncher(stats.StatsReporter):
             if (self.state_machine.complete and self.keyscan_future
                 and self.keyscan_future.done()):
                 keys = self.keyscan_future.result()
-                node.host_keys = keys
+                if keys:
+                    node.host_keys = keys
                 self.log.debug(f"Node {node.id} is ready")
                 node.state = zk.READY
                 self.zk.storeNode(node)
@@ -206,6 +210,7 @@ class StateMachineNodeLauncher(stats.StatsReporter):
                                node.interface_ip)
                 future = self.manager.keyscan_worker.submit(
                     keyscan,
+                    self.handler.pool.host_key_checking,
                     node.id, node.interface_ip,
                     node.connection_type, node.connection_port,
                     self.manager.provider.boot_timeout)
@@ -717,6 +722,7 @@ class Instance:
     * shell_type: str
     * connection_port: str
     * connection_type: str
+    * host_keys: [str]
     """
     def __init__(self):
         self.ready = False