Add a monkey patch that will squelch warnings for legacy Fog gems

Gemfile

@@ -95,7 +95,9 @@ gem 'mini_magick'
 
 # for backups
 gem 'fog-aws', '~> 3.3'
-gem 'fog-core', '~> 2.1'
+# Locked until fog-google resolves https://github.com/fog/fog-google/issues/421.
+# Also see config/initializers/fog_core_patch.rb.
+gem 'fog-core', '= 2.1.0'
 gem 'fog-google', '~> 1.8'
 gem 'fog-local', '~> 0.6'
 gem 'fog-openstack', '~> 1.0'

Gemfile.lock

@@ -1005,7 +1005,7 @@ DEPENDENCIES
   flowdock (~> 0.7)
   fog-aliyun (~> 0.3)
   fog-aws (~> 3.3)
-  fog-core (~> 2.1)
+  fog-core (= 2.1.0)
   fog-google (~> 1.8)
   fog-local (~> 0.6)
   fog-openstack (~> 1.0)

config/initializers/fog_core_patch.rb

+# fog-core v2 changed the namespace format:
+#
+# Old: Fog::<service>::<provider> (e.g. Fog::Storage::AWS).
+# New: Fog::<provider>::<service> (e.g. Fog::AWS::Storage)
+#
+# To preserve backwards compatibility, fog-core v2.1.0 tries to load the
+# old schema first, but falls back to the older version if that
+# fails. This creates misleading warnings with fog-aws. See
+# https://github.com/fog/fog-aws/issues/504#issuecomment-468067991 for
+# more details.
+#
+# fog-core v2.1.2 reverses the load order
+# (https://github.com/fog/fog-core/pull/229), which works for fog-aws
+# but causes a stream of deprecation warnings for fog-google.
+# fog-google locked the dependency on fog-core v2.1.0 as a result
+# (https://github.com/fog/fog-google/issues/421) until the new namespace
+# is supported.
+#
+# Since we currently have some Fog gems that have not been updated, this
+# monkey patch makes a smarter decision about which namespace to try
+# first. This squelches a significant number of warning messages.
+#
+# Since this patch is mostly cosmetic, it can be removed safely at any
+# time, but it's probably best to wait until the following issues are
+# closed:
+#
+# fog-google: https://github.com/fog/fog-google/issues/421
+# fog-rackspace: https://github.com/fog/fog-rackspace/issues/29
+# fog-aliyun: https://github.com/fog/fog-aliyun/issues/23
+module Fog
+  module ServicesMixin
+    # Gems that have not yet updated with the new fog-core namespace
+    LEGACY_FOG_PROVIDERS = %w(google rackspace aliyun).freeze
+
+    def service_provider_constant(service_name, provider_name)
+      args = service_provider_search_args(service_name, provider_name)
+      Fog.const_get(args.first).const_get(*const_get_args(args.second))
+    rescue NameError  # Try to find the constant from in an alternate location
+      Fog.const_get(args.second).const_get(*const_get_args(args.first))
+    end
+
+    def service_provider_search_args(service_name, provider_name)
+      if LEGACY_FOG_PROVIDERS.include?(provider_name.downcase)
+        [service_name, provider_name]
+      else
+        [provider_name, service_name]
+      end
+    end
+  end
+end