securityscanner: add a min image id option

This will enable us to force some instances of the securityworker to
scan only new images.

config.py

@@ -313,6 +313,9 @@ class DefaultConfig(object):
   # The number of seconds between indexing intervals in the security scanner
   SECURITY_SCANNER_INDEXING_INTERVAL = 30
 
+  # If specified, the security scanner will only index images newer than the provided ID.
+  SECURITY_SCANNER_INDEXING_MIN_ID = None
+
   # If specified, the endpoint to be used for all POST calls to the security scanner.
   SECURITY_SCANNER_ENDPOINT_BATCH = None
 

data/model/image.py

@@ -495,10 +495,13 @@ def get_image_id():
   return Image.id
 
 
-def get_images_eligible_for_scan(clair_version):
+def get_images_eligible_for_scan(clair_version, min_id=None):
   """ Returns a query that gives all images eligible for a clair scan """
-  return (get_image_with_storage_and_parent_base()
-          .where(Image.security_indexed_engine < clair_version))
+  query = (get_image_with_storage_and_parent_base()
+           .where(Image.security_indexed_engine < clair_version))
+  if min_id is not None:
+    query = query.where(Image.id >= min_id)
+  return query
 
 
 def get_image_with_storage_and_parent_base():

test/test_secscan.py

@@ -589,11 +589,11 @@ class TestSecurityScanner(unittest.TestCase):
 
     # Ensure no images are available for scanning.
     self.assertIsNone(model.image.get_min_id_for_sec_scan(expected_version))
-    self.assertTrue(len(model.image.get_images_eligible_for_scan(expected_version)) == 0)
+    self.assertTrue(len(model.image.get_images_eligible_for_scan(expected_version, None)) == 0)
 
     # Check for a higher version.
     self.assertIsNotNone(model.image.get_min_id_for_sec_scan(expected_version + 1))
-    self.assertTrue(len(model.image.get_images_eligible_for_scan(expected_version + 1)) > 0)
+    self.assertTrue(len(model.image.get_images_eligible_for_scan(expected_version + 1, None)) > 0)
 
   def test_notification_worker(self):
     layer1 = model.tag.get_tag_image(ADMIN_ACCESS_USER, SIMPLE_REPO, 'latest', include_storage=True)

workers/securityworker.py

@@ -42,7 +42,7 @@ class SecurityWorker(Worker):
 
   def _index_images(self):
     def batch_query():
-      return get_images_eligible_for_scan(self._target_version)
+      return get_images_eligible_for_scan(self._target_version, app.config.get('SECURITY_SCANNER_INDEXING_MIN_ID', None))
 
     # Get the ID of the last image we can analyze. Will be None if there are no images in the
     # database.