fix recursion loop

refs INTEROP-8632

Test plan
- Change the constant in DeveloperKey::DEFAULT_KEY_NAME
- restart your docker container for good measure
- run DeveloperKey.default in a console (might have to do dc down && dc
  up)
- there should be no infinite loop. a new Dk should have been reated.
- hard-delete the new key (DK.where(id: DK.default).delete_all), undo
  your DEFAULT_KEY_NAME code change
- restart your docker container for good measure
- try to turn off the default DK account binding in the UI, it won't let
  you (original protection change)

Change-Id: I7a41435cd0c0eda7fa552bae0be4adfd261b9e10
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/354641
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
Reviewed-by: Steven McGee <steve.mcgee@instructure.com>
QA-Review: Steven McGee <steve.mcgee@instructure.com>
Product-Review: Evan Battaglia <ebattaglia@instructure.com>

app/models/developer_key.rb

@@ -177,11 +177,11 @@ class DeveloperKey < ActiveRecord::Base
   end
 
   class << self
-    def default
-      get_special_key(DeveloperKey::DEFAULT_KEY_NAME)
+    def default(create_if_missing: true)
+      get_special_key(DeveloperKey::DEFAULT_KEY_NAME, create_if_missing:)
     end
 
-    def get_special_key(default_key_name)
+    def get_special_key(default_key_name, create_if_missing: true)
       Shard.birth.activate do
         @special_keys ||= {}
 
@@ -192,6 +192,7 @@ class DeveloperKey < ActiveRecord::Base
           key = DeveloperKey.where(id: key_id).first
         end
         return @special_keys[default_key_name] = key if key
+        return nil unless create_if_missing
 
         key = DeveloperKey.create!(name: default_key_name)
         key.developer_key_account_bindings.update_all(workflow_state: "on")

app/models/developer_key_account_binding.rb

@@ -123,16 +123,19 @@ class DeveloperKeyAccountBinding < ApplicationRecord
 
   private
 
+  def for_default_key?
+    developer_key&.name == DeveloperKey::DEFAULT_KEY_NAME &&
+      developer_key == DeveloperKey.default(create_if_missing: false)
+  end
+
   # DeveloperKey.default is for user-generated tokens and must always be ON
   def enable_default_key
-    if developer_key.name == DeveloperKey::DEFAULT_KEY_NAME && developer_key == DeveloperKey.default
-      self.workflow_state = :on
-    end
+    self.workflow_state = :on if !on? && for_default_key?
   end
 
   # DeveloperKey.default is for user-generated tokens and must always be ON
   def protect_default_key_binding
-    raise "Please don't turn off the default developer key" if developer_key.name == DeveloperKey::DEFAULT_KEY_NAME && developer_key == DeveloperKey.default && !on?
+    raise "Please don't turn off the default developer key" if !on? && for_default_key?
   end
 
   def update_lti_registration_account_binding

spec/models/developer_key_spec.rb

@@ -1186,6 +1186,26 @@ describe DeveloperKey do
   end
 
   describe "default" do
+    context "when create_if_missing: false is passed" do
+      before do
+        allow(DeveloperKey).to receive(:get_special_key) do |*args, **kwargs|
+          DeveloperKey.original_get_special_key(*args, **kwargs)
+        end
+      end
+
+      it "does not create a key" do
+        DeveloperKey.delete_all
+        expect(DeveloperKey.count).to eq 0
+        DeveloperKey.default(create_if_missing: false)
+        expect(DeveloperKey.count).to eq 0
+      end
+
+      it "finds existing keys" do
+        expect(DeveloperKey.default).to_not be_nil
+        expect(DeveloperKey.default(create_if_missing: false)).to_not be_nil
+      end
+    end
+
     context "sharding" do
       specs_require_sharding
 

spec/spec_helper.rb

@@ -1027,12 +1027,20 @@ Shoulda::Matchers.configure do |config|
 end
 
 module DeveloperKeyStubs
-  def get_special_key(default_key_name)
+  @@original_get_special_key = DeveloperKey.method(:get_special_key)
+
+  def original_get_special_key(*args, **kwargs)
+    @@original_get_special_key.call(*args, **kwargs)
+  end
+
+  def get_special_key(default_key_name, create_if_missing: true)
     Shard.birth.activate do
       @special_keys ||= {}
 
       # TODO: we have to do this because tests run in transactions
       testkey = DeveloperKey.where(name: default_key_name).first_or_initialize
+      return nil if testkey.new_record? && !create_if_missing
+
       testkey.auto_expire_tokens = false if testkey.new_record?
       testkey.sns_arn = "arn:aws:s3:us-east-1:12345678910:foo/bar"
       testkey.save! if testkey.changed?