Use luci-config for infrequently changing settings, part 2.

appengine/auth_service/importer.py

Index: appengine/auth_service/importer.py
diff --git a/appengine/auth_service/importer.py b/appengine/auth_service/importer.py
index 8e7ec52ba8ef210f288aa65274b1195ff7122f86..ff2a1037ff6706fde3131963c3b0d02fee9bf2fd 100644
--- a/appengine/auth_service/importer.py
+++ b/appengine/auth_service/importer.py
@@ -35,17 +35,22 @@ service too.
 
 import collections
 import contextlib
+import json
 import logging
 import StringIO
 import tarfile
 
 from google.appengine.ext import ndb
 
+from google import protobuf
+
 from components import auth
 from components import net
 from components import utils
 from components.auth import model
 
+from proto import config_pb2
+
 
 class BundleImportError(Exception):
   """Base class for errors while fetching external bundle."""
@@ -94,92 +99,131 @@ def config_key():
 
 class GroupImporterConfig(ndb.Model):
   """Singleton entity with group importer configuration JSON."""
-  config = ndb.JsonProperty()
+  config = ndb.TextProperty() # legacy field with JSON config
+  config_proto = ndb.TextProperty()
   modified_by = auth.IdentityProperty(indexed=False)
   modified_ts = ndb.DateTimeProperty(auto_now=True, indexed=False)
 
 
-def is_valid_config(config):
-  """Checks config for correctness."""
-  if not isinstance(config, list):
-    return False
+def legacy_json_config_to_proto(config_json):
+  """Converts legacy JSON config to config_pb2.GroupImporterConfig message.
 
-  seen_systems = set(['external'])
-  seen_groups = set()
+  TODO(vadimsh): Remove once all instances of auth service use protobuf configs.
+  """
+  try:
+    config = json.loads(config_json)
+  except ValueError as ex:
+    logging.error('Invalid JSON: %s', ex)
+    return None
+  msg = config_pb2.GroupImporterConfig()
   for item in config:
-    if not isinstance(item, dict):
-      return False
-
-    # 'format' is an optional string describing the format of the imported
-    # source. The default format is 'tarball'.
     fmt = item.get('format', 'tarball')
-    if fmt not in ['tarball', 'plainlist']:
-      return False
-
-    # 'url' is a required string: where to fetch groups from.
-    url = item.get('url')
-    if not url or not isinstance(url, basestring):
-      return False
-
-    # 'oauth_scopes' is an optional list of strings: used when generating OAuth
-    # access_token to put in Authorization header.
-    oauth_scopes = item.get('oauth_scopes')
-    if oauth_scopes is not None:
-      if not all(isinstance(x, basestring) for x in oauth_scopes):
-        return False
-
-    # 'domain' is an optional string: will be used when constructing emails from
-    # naked usernames found in imported groups.
-    domain = item.get('domain')
-    if domain and not isinstance(domain, basestring):
-      return False
-
-    # 'tarball' format uses 'systems' and 'groups' fields.
     if fmt == 'tarball':
-      # 'systems' is a required list of strings: group systems expected to be
-      # found in the archive (they act as prefixes to group names, e.g 'ldap').
-      systems = item.get('systems')
-      if not systems or not isinstance(systems, list):
-        return False
-      if not all(isinstance(x, basestring) for x in systems):
-        return False
-
-      # There should be no overlap in systems between different bundles.
-      if set(systems) & seen_systems:
-        return False
-      seen_systems.update(systems)
-
-      # 'groups' is an optional list of strings: if given, filters imported
-      # groups only to this list.
-      groups = item.get('groups')
-      if groups and not all(isinstance(x, basestring) for x in groups):
-        return False
+      entry = msg.tarball.add()
+    elif fmt == 'plainlist':
+      entry = msg.plainlist.add()
+    else:
+      logging.error('Unrecognized format: %s', fmt)
+      continue
+    entry.url = item.get('url') or ''
+    entry.oauth_scopes.extend(item.get('oauth_scopes') or [])
+    if 'domain' in item:
+      entry.domain = item['domain']
+    if fmt == 'tarball':
+      entry.systems.extend(item.get('systems') or [])
+      entry.groups.extend(item.get('groups') or [])
     elif fmt == 'plainlist':
-      # 'group' is a required name of imported group. The full group name will
-      # be 'external/<group>'.
-      group = item.get('group')
-      if not group or not isinstance(group, basestring) or group in seen_groups:
-        return False
-      seen_groups.add(group)
+      entry.group = item.get('group') or ''
     else:
-      assert False, 'Unreachable'
+      assert False, 'Not reachable'
+  return msg
 
-  return True
 
+def validate_config(config):
+  """Checks config_pb2.GroupImporterConfig for correctness.
 
-def read_config():
-  """Returns currently stored config or [] if not set."""
+  Raises:
+    ValueError if config has invalid structure.
+  """
+  if not isinstance(config, config_pb2.GroupImporterConfig):
+    raise ValueError('Not GroupImporterConfig proto message')
+
+  # TODO(vadimsh): Can be made stricter.
+
+  # Validate fields common to Tarball and Plainlist.
+  for entry in list(config.tarball) + list(config.plainlist):
+    if not entry.url:
+      raise ValueError(
+          '"url" field is required in %s' % entry.__class__.__name__)
+
+  # Validate tarball fields.
+  seen_systems = set(['external'])
+  for tarball in config.tarball:
+    if not tarball.systems:
+      raise ValueError(
+          '"tarball" entry "%s" needs "systems" field' % tarball.url)
+    # There should be no overlap in systems between different bundles.
+    twice = set(tarball.systems) & seen_systems
+    if twice:
+      raise ValueError(
+          'A system is imported twice by "%s": %s' %
+          (tarball.url, sorted(twice)))
+    seen_systems.update(tarball.systems)
+
+  # Validate plainlist fields.
+  seen_groups = set()
+  for plainlist in config.plainlist:
+    if not plainlist.group:
+      raise ValueError(
+          '"plainlist" entry "%s" needs "group" field' % plainlist.url)
+    if plainlist.group in seen_groups:
+      raise ValueError(
+          'In "%s" the group is imported twice: %s' %
+          (plainlist.url, plainlist.group))
+    seen_groups.add(plainlist.group)
+
+
+def read_config_text():
+  """Returns importer config as a text blob (or '' if not set)."""
+  e = config_key().get()
+  if not e:
+    return ''
+  if e.config_proto:
+    return e.config_proto
+  if e.config:
+    msg = legacy_json_config_to_proto(e.config)
+    if not msg:
+      return ''
+    return protobuf.text_format.MessageToString(msg)
+  return ''
+
+
+def read_legacy_config():
+  """Returns legacy JSON config stored in GroupImporterConfig entity.
+
+  TODO(vadimsh): Remove once all instance of auth service use protobuf configs.
+  """
+  # Note: we do not care to do it in transaction.
   e = config_key().get()
-  return (e.config if e else []) or []
+  return e.config if e else None
 
 
-def write_config(config):
-  """Updates stored configuration."""
-  if not is_valid_config(config):
-    raise ValueError('Invalid config')
+def write_config_text(text):
+  """Validates config text blobs and puts it into the datastore.
+
+  Raises:
+    ValueError on invalid format.
+  """
+  msg = config_pb2.GroupImporterConfig()
+  try:
+    protobuf.text_format.Merge(text, msg)
+  except protobuf.text_format.ParseError as ex:
+    raise ValueError('Config is badly formated: %s' % ex)
+  validate_config(msg)
   e = GroupImporterConfig(
       key=config_key(),
-      config=config,
+      config=read_legacy_config(),
+      config_proto=text,
       modified_by=auth.get_current_identity())
   e.put()
 
@@ -190,34 +234,40 @@ def import_external_groups():
   Runs as a cron task. Raises BundleImportError in case of import errors.
   """
   # Missing config is not a error.
-  config = read_config()
-  if not config:
+  config_text = read_config_text()
+  if not config_text:
     logging.info('Not configured')
     return
-  if not is_valid_config(config):
-    raise BundleImportError('Bad config')
+  config = config_pb2.GroupImporterConfig()
+  try:
+    protobuf.text_format.Merge(config_text, config)
+  except protobuf.text_format.ParseError as ex:
+    raise BundleImportError('Bad config format: %s' % ex)
+  try:
+    validate_config(config)
+  except ValueError as ex:
+    raise BundleImportError('Bad config structure: %s' % ex)
 
   # Fetch all files specified in config in parallel.
-  futures = [fetch_file_async(p['url'], p.get('oauth_scopes')) for p in config]
+  entries = list(config.tarball) + list(config.plainlist)
+  futures = [fetch_file_async(e.url, e.oauth_scopes) for e in entries]
 
   # {system name -> group name -> list of identities}
   bundles = {}
-  for p, future in zip(config, futures):
-    fmt = p.get('format', 'tarball')
-
+  for e, future in zip(entries, futures):
     # Unpack tarball into {system name -> group name -> list of identities}.
-    if fmt == 'tarball':
+    if isinstance(e, config_pb2.GroupImporterConfig.TarballEntry):
       fetched = load_tarball(
-          future.get_result(), p['systems'], p.get('groups'), p.get('domain'))
+          future.get_result(), e.systems, e.groups, e.domain)
       assert not (
           set(fetched) & set(bundles)), (fetched.keys(), bundles.keys())
       bundles.update(fetched)
       continue
 
     # Add plainlist group to 'external/*' bundle.
-    if fmt == 'plainlist':
-      group = load_group_file(future.get_result(), p.get('domain'))
-      name = 'external/%s' % p['group']
+    if isinstance(e, config_pb2.GroupImporterConfig.PlainlistEntry):
+      group = load_group_file(future.get_result(), e.domain)
+      name = 'external/%s' % e.group
       if 'external' not in bundles:
         bundles['external'] = {}
       assert name not in bundles['external'], name