Switch ipresolver to always be defined in the storage context

We now use a no-op IP resolver instead of an IF check

Fixes https://jira.prod.coreos.systems/browse/QS-38

storage/__init__.py

@@ -4,6 +4,7 @@ from storage.fakestorage import FakeStorage
 from storage.distributedstorage import DistributedStorage
 from storage.swift import SwiftStorage
 from storage.downloadproxy import DownloadProxy
+from util.ipresolver import NoopIPResolver
 
 STORAGE_DRIVER_CLASSES = {
   'LocalStorage': LocalStorage,
@@ -33,7 +34,7 @@ class StorageContext(object):
     self.metric_queue = metric_queue
     self.chunk_cleanup_queue = chunk_cleanup_queue
     self.config_provider = config_provider
-    self.ip_resolver = ip_resolver
+    self.ip_resolver = ip_resolver or NoopIPResolver()
 
 
 class Storage(object):

storage/cloud.py

@@ -622,7 +622,7 @@ class CloudFrontedS3Storage(S3Storage):
       
     resolved_ip_info = None
     logger.debug('Got direct download request for path "%s" with IP "%s"', path, request_ip)
-    if request_ip is not None and self._context.ip_resolver is not None:
+    if request_ip is not None:
       # Lookup the IP address in our resolution table and determine whether it is under AWS.
       # If it is, then return an S3 signed URL, since we are in-network.
       resolved_ip_info = self._context.ip_resolver.resolve_ip(request_ip)

util/ipresolver/__init__.py

@@ -2,6 +2,9 @@ import logging
 import json
 import requests
 
+from abc import ABCMeta, abstractmethod
+from six import add_metaclass
+
 from cachetools import ttl_cache, lru_cache
 from collections import namedtuple, defaultdict
 from netaddr import IPNetwork, IPAddress, IPSet, AddrFormatError
@@ -9,6 +12,8 @@ from netaddr import IPNetwork, IPAddress, IPSet, AddrFormatError
 import geoip2.database
 import geoip2.errors
 
+from util.abchelpers import nooper
+
 ResolvedLocation = namedtuple('ResolvedLocation', ['provider', 'region', 'service', 'sync_token'])
 
 logger = logging.getLogger(__name__)
@@ -28,7 +33,25 @@ def update_resolver_datafiles():
       f.write(response.text)
       logger.debug('Successfully wrote %s', filename)
 
-class IPResolver(object):
+
+@add_metaclass(ABCMeta)
+class IPResolverInterface(object):
+  """ Helper class for resolving information about an IP address. """
+  @abstractmethod
+  def resolve_ip(self, ip_address):
+    """ Attempts to return resolved information about the specified IP Address. If such an attempt
+        fails, returns None.
+    """
+    pass
+
+
+@nooper
+class NoopIPResolver(IPResolverInterface):
+  """ No-op version of the security scanner API. """
+  pass
+
+
+class IPResolver(IPResolverInterface):
   def __init__(self, app):
     self.app = app
     self.geoip_db = geoip2.database.Reader('util/ipresolver/GeoLite2-Country.mmdb')