[autoscaler] Sometimes instances are restarted even when they don't need to be (#1385)

* fix hash

* Update autoscaler.py

python/ray/autoscaler/autoscaler.py

@@ -493,7 +493,8 @@ def with_head_node_ip(cmds):
 
 def hash_launch_conf(node_conf, auth):
     hasher = hashlib.sha1()
-    hasher.update(json.dumps([node_conf, auth]).encode("utf-8"))
+    hasher.update(
+        json.dumps([node_conf, auth], sort_keys=True).encode("utf-8"))
     return hasher.hexdigest()
 
 
@@ -516,7 +517,7 @@ def hash_runtime_conf(file_mounts, extra_objs):
                 hasher.update(f.read().encode("utf-8"))
 
     hasher.update(json.dumps(sorted(file_mounts.items())).encode("utf-8"))
-    hasher.update(json.dumps(extra_objs).encode("utf-8"))
+    hasher.update(json.dumps(extra_objs, sort_keys=True).encode("utf-8"))
     for local_path in sorted(file_mounts.values()):
         add_content_hashes(local_path)
 

python/ray/autoscaler/commands.py

@@ -80,12 +80,13 @@ def get_or_create_head_node(config, no_restart):
     if not head_node:
         confirm("This will create a new cluster")
     elif not no_restart:
-        confirm("This will restart your cluster")
+        confirm("This will restart cluster services")
 
     launch_hash = hash_launch_conf(config["head_node"], config["auth"])
     if head_node is None or provider.node_tags(head_node).get(
             TAG_RAY_LAUNCH_CONFIG) != launch_hash:
         if head_node is not None:
+            confirm("Head node config out-of-date. It will be terminated")
             print("Terminating outdated head node {}".format(head_node))
             provider.terminate_node(head_node)
         print("Launching new head node...")