Protocol, UI and smoke test for Primary <-> Replica linking process.

services/auth_service/common/replication.py

 # Copyright 2014 The Swarming Authors. All rights reserved.
 # Use of this source code is governed by the Apache v2.0 license that can be
 # found in the LICENSE file.
 
 """Primary side of Primary <-> Replica protocol."""
 
 from google.appengine.ext import ndb
 
 from components import datastore_utils
 
@@ skipping 10 matching lines @@
   # How to convert this entity to serializable dict.
   serializable_properties = {
     'replica_url': datastore_utils.READABLE,
     'auth_db_rev': datastore_utils.READABLE,
     'rev_modified_ts': datastore_utils.READABLE,
   }
 
   # URL of a host to push AuthDB updates to, especially useful on dev_appserver.
   replica_url = ndb.StringProperty(indexed=False)
   # Revision of auth DB replica is synced to.
-  auth_db_rev = ndb.IntegerProperty(indexed=False)
+  auth_db_rev = ndb.IntegerProperty(default=0, indexed=False)
   # Time when auth_db_rev was created (by primary clock).
   rev_modified_ts = ndb.DateTimeProperty(indexed=False)
-  # Secret known to both Primary and Replica.
-  shared_secret = ndb.BlobProperty(indexed=False)

[M-A, 2014/06/30 01:18:31]

Why not use asymmetric encryption?

[vadimsh, 2014/06/30 22:58:52]

Good idea. I initially (~several months ago) wanted to do so, and forgot since
then. I'll use built-in APIs
(https://developers.google.com/appengine/docs/python/appidentity/functions):
sign_blob and get_public_certificates.

 
 
-def register_replica(app_id, replica_url, shared_secret):
-  """Create a new AuthReplicaState or reset the state of existing one."""

[M-A, 2014/06/30 01:18:31]

Creates
resets

[vadimsh, 2014/06/30 22:58:52]

Done.

+def register_replica(app_id, replica_url):
+  """Creates a new AuthReplicaState or resets the state of existing one."""
   ent = AuthReplicaState(
       id=app_id,
       parent=REPLICAS_ROOT_KEY,
-      replica_url=replica_url,
-      auth_db_rev=0,

[M-A, 2014/06/30 01:18:31]

Why not use default=0?

[vadimsh, 2014/06/30 22:58:52]

Done.

-      rev_modified_ts=None,

[M-A, 2014/06/30 01:18:31]

Not really necessary?

[vadimsh, 2014/06/30 22:58:52]

Done.

-      shared_secret=shared_secret)
+      replica_url=replica_url)
   ent.put()