run canvas_cache config earlier in initialization order

closes FOO-1896

Change-Id: I44458ee05813c2c131366fa9f1136d67e24b8d28
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/263347
Reviewed-by: Jeremy Stanley <jeremy@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
QA-Review: Jeremy Stanley <jeremy@instructure.com>
QA-Review: Jackson Howe <jackson.howe@instructure.com>
Product-Review: Ethan Vizitei <evizitei@instructure.com>
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>

config/application.rb

@@ -374,6 +374,10 @@ module CanvasRails
       end
     end
 
+    initializer "canvas.cache_config", before: "canvas.extend_shard" do
+      CanvasCacheInit.apply!
+    end
+
     initializer "canvas.extend_shard", before: "active_record.initialize_database" do
       # have to do this before the default shard loads
       Switchman::Shard.serialize :settings, Hash

config/initializers/canvas_cache.rb

@@ -16,15 +16,4 @@
 # You should have received a copy of the GNU Affero General Public License along
 # with this program. If not, see <http://www.gnu.org/licenses/>.
 
-# to avoid having to pull this out as a full engine yet.
+CanvasCacheInit.apply!
-# we may extract Setting into an engine or an abstract gem
-# or something, for now this pattern breaks the explicit dependency.
-CanvasCache.settings_store = Setting
-
-# It would be great to pull out Canvas::Errors as a gem, and we should do so.
-# The problem is it has a dependency on RequestContextGenerator, which
-# has a dependency on Canvas::Security, which has a dependency on
-# our caching, and so we have to break the chain somewhere.  We're starting
-# with the caching.  TODO: Once canvas errors is out on it's own we can let
-# CanvasCache take a dependency on it directly and forego this injection.
-CanvasCache.on_captured_error = ->(e){ Canvas::Errors.capture_exception(:redis, e, :warn) }

lib/canvas_cache_init.rb

@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+#
+# Copyright (C) 2021 - present Instructure, Inc.
+#
+# This file is part of Canvas.
+#
+# Canvas is free software: you can redistribute it and/or modify it under
+# the terms of the GNU Affero General Public License as published by the Free
+# Software Foundation, version 3 of the License.
+#
+# Canvas is distributed in the hope that it will be useful, but WITHOUT ANY
+# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+# A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Affero General Public License along
+# with this program. If not, see <http://www.gnu.org/licenses/>.
+
+# This would normally be in an initializer, but
+# other initialization processes can depend on it.
+# By putting it in this module we can invoke it from
+# an initializer in config/initializers and also from application.rb to force
+# it to run early in the init order.
+class CanvasCacheInit
+  def self.apply!
+    unless CanvasCache.settings_store(true) == Setting
+      # to avoid having to pull this out as a full engine yet.
+      # we may extract Setting into an engine or an abstract gem
+      # or something, for now this pattern breaks the explicit dependency.
+      CanvasCache.settings_store = Setting
+
+      # It would be great to pull out Canvas::Errors as a gem, and we should do so.
+      # The problem is it has a dependency on RequestContextGenerator, which
+      # has a dependency on Canvas::Security, which has a dependency on
+      # our caching, and so we have to break the chain somewhere.  We're starting
+      # with the caching.  TODO: Once canvas errors is out on it's own we can let
+      # CanvasCache take a dependency on it directly and forego this injection.
+      CanvasCache.on_captured_error = ->(e){ Canvas::Errors.capture_exception(:redis, e, :warn) }
+    end
+  end
+end