Static driver: fix node registration

After fulfilling a node request from zuul, it was possible for the
static driver to not have an accurate representation of the nodes
that were registered in ZK. It needs to re-read from ZK on each
node deletion notification.

Change-Id: I82e6934edabcb0c720e15593fb38e8fcfafa121c

nodepool/driver/static/provider.py

@@ -165,11 +165,11 @@ class StaticNodeProvider(Provider):
 
     def _start(self, zk_conn):
         self.zk = zk_conn
-        self.registered = self.getRegisteredNodeHostnames()
+        registered = self.getRegisteredNodeHostnames()
 
         for pool in self.provider.pools.values():
             for node in pool.nodes:
-                current_count = self.registered[node["name"]]
+                current_count = registered[node["name"]]
 
                 # Register nodes to synchronize with our configuration.
                 if current_count < node["max-parallel-jobs"]:
@@ -197,10 +197,10 @@ class StaticNodeProvider(Provider):
         # De-register nodes to synchronize with our configuration.
         # This case covers any registered nodes that no longer appear in
         # the config.
-        for hostname in list(self.registered):
+        for hostname in list(registered):
             if hostname not in self.static_nodes:
                 try:
-                    self.deregisterNode(self.registered[hostname], hostname)
+                    self.deregisterNode(registered[hostname], hostname)
                 except Exception:
                     self.log.exception("Couldn't deregister static node:")
                     continue
@@ -248,7 +248,13 @@ class StaticNodeProvider(Provider):
             return
 
         static_node = self.static_nodes[node.hostname]
-        current_count = self.registered[node.hostname]
+        try:
+            registered = self.getRegisteredNodeHostnames()
+        except Exception:
+            self.log.exception(
+                "Cannot get registered hostnames for node re-registration:")
+            return
+        current_count = registered[node.hostname]
 
         # It's possible we were not able to de-register nodes due to a config
         # change (because they were in use). In that case, don't bother to

nodepool/tests/test_driver_static.py

@@ -200,3 +200,33 @@ class TestDriverStatic(tests.DBTestCase):
         req = self.waitForNodeRequest(req)
         self.assertEqual(req.state, zk.FULFILLED)
         self.assertEqual(len(req.nodes), 1)
+
+    def test_static_request_handled(self):
+        '''
+        Test that a node is reregistered after handling a request.
+        '''
+        configfile = self.setup_config('static-basic.yaml')
+        pool = self.useNodepool(configfile, watermark_sleep=1)
+        pool.start()
+        nodes = self.waitForNodes('fake-label')
+        self.assertEqual(len(nodes), 1)
+
+        req = zk.NodeRequest()
+        req.state = zk.REQUESTED
+        req.node_types.append('fake-label')
+        self.zk.storeNodeRequest(req)
+
+        self.log.debug("Waiting for request %s", req.id)
+        req = self.waitForNodeRequest(req)
+        self.assertEqual(req.state, zk.FULFILLED)
+        self.assertEqual(len(req.nodes), 1)
+        self.assertEqual(req.nodes[0], nodes[0].id)
+
+        # Mark node as used
+        nodes[0].state = zk.USED
+        self.zk.storeNode(nodes[0])
+
+        # Our single node should have been used, deleted, then reregistered
+        new_nodes = self.waitForNodes('fake-label')
+        self.assertEqual(len(new_nodes), 1)
+        self.assertEqual(nodes[0].hostname, new_nodes[0].hostname)