[Fix #50604] Restore compatibility of ARE configs with eager loading mode

Configure ActiveRecord::Encryption (ARE) on ActiveRecord::Base (AR)
loading, so that ARE configs are ready before AR models start using
`encrypts` to declare encrypted attributes.

This means that you can add ARE configurations in initializers, as long
as you don't trigger the loading of ActiveRecord::Base or your AR models
in prior initializers.

activerecord/CHANGELOG.md

@@ -1,3 +1,9 @@
+*   Fix an issue where `ActiveRecord::Encryption` configurations are not ready before the loading
+    of Active Record models, when an application is eager loaded. As a result, encrypted attributes
+    could be misconfigured in some cases.
+
+    *Maxime Réty*
+
 *   Deprecate defining an `enum` with keyword arguments.
 
     ```ruby

activerecord/lib/active_record/railtie.rb

@@ -378,23 +378,20 @@ To keep using the current cache store, you can turn off cache versioning entirel
     end
 
     initializer "active_record_encryption.configuration" do |app|
-      auto_filtered_parameters = ActiveRecord::Encryption::AutoFilteredParameters.new(app)
-
-      config.after_initialize do |app|
+      ActiveSupport.on_load(:active_record) do
         ActiveRecord::Encryption.configure \
           primary_key: app.credentials.dig(:active_record_encryption, :primary_key),
           deterministic_key: app.credentials.dig(:active_record_encryption, :deterministic_key),
           key_derivation_salt: app.credentials.dig(:active_record_encryption, :key_derivation_salt),
-          **config.active_record.encryption
+          **app.config.active_record.encryption
 
+        auto_filtered_parameters = ActiveRecord::Encryption::AutoFilteredParameters.new(app)
         auto_filtered_parameters.enable if ActiveRecord::Encryption.config.add_to_filter_parameters
 
-        ActiveSupport.on_load(:active_record) do
-          # Support extended queries for deterministic attributes and validations
-          if ActiveRecord::Encryption.config.extend_queries
-            ActiveRecord::Encryption::ExtendedDeterministicQueries.install_support
-            ActiveRecord::Encryption::ExtendedDeterministicUniquenessValidator.install_support
-          end
+        # Support extended queries for deterministic attributes and validations
+        if ActiveRecord::Encryption.config.extend_queries
+          ActiveRecord::Encryption::ExtendedDeterministicQueries.install_support
+          ActiveRecord::Encryption::ExtendedDeterministicUniquenessValidator.install_support
         end
       end
 

railties/test/application/configuration_test.rb

@@ -31,6 +31,13 @@ class ::MySanitizerVendor < ::Rails::HTML::Sanitizer
   end
 end
 
+class ::MyCustomKeyProvider
+  attr_reader :primary_key
+  def initialize(primary_key); @primary_key = primary_key; end
+end
+
+class ::MyOldKeyProvider; end
+
 module ApplicationTests
   class ConfigurationTest < ActiveSupport::TestCase
     include ActiveSupport::Testing::Isolation
@@ -3819,6 +3826,74 @@ module ApplicationTests
       assert_not_includes ActiveRecord::Base.filter_attributes, :content
     end
 
+    test "ActiveRecord::Encryption.config is ready for encrypted attributes when app is lazy loaded" do
+      add_to_config <<-RUBY
+        config.enable_reloading = false
+        config.eager_load = false
+      RUBY
+
+      app_file "config/initializers/active_record.rb", <<-RUBY
+        Rails.application.config.active_record.encryption.primary_key = "dummy_key"
+        Rails.application.config.active_record.encryption.previous = [ { key_provider: MyOldKeyProvider.new } ]
+
+        ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")
+        ActiveRecord::Migration.verbose = false
+        ActiveRecord::Schema.define(version: 1) do
+          create_table :posts do |t|
+            t.string :content
+          end
+        end
+
+        ActiveRecord::Base.connection.schema_cache.add("posts")
+      RUBY
+
+      app_file "app/models/post.rb", <<-RUBY
+        class Post < ActiveRecord::Base
+          encrypts :content, key_provider: MyCustomKeyProvider.new(ActiveRecord::Encryption.config.primary_key)
+        end
+      RUBY
+
+      app "development"
+
+      assert_kind_of ::MyOldKeyProvider, Post.attribute_types["content"].previous_schemes.first.key_provider
+      assert_kind_of ::MyCustomKeyProvider, Post.attribute_types["content"].scheme.key_provider
+      assert_equal "dummy_key", Post.attribute_types["content"].scheme.key_provider.primary_key
+    end
+
+    test "ActiveRecord::Encryption.config is ready for encrypted attributes when app is eager loaded" do
+      add_to_config <<-RUBY
+        config.enable_reloading = false
+        config.eager_load = true
+      RUBY
+
+      app_file "app/models/post.rb", <<-RUBY
+        class Post < ActiveRecord::Base
+          encrypts :content, key_provider: MyCustomKeyProvider.new(ActiveRecord::Encryption.config.primary_key)
+        end
+      RUBY
+
+      app_file "config/initializers/active_record.rb", <<-RUBY
+        Rails.application.config.active_record.encryption.primary_key = "dummy_key"
+        Rails.application.config.active_record.encryption.previous = [ { key_provider: MyOldKeyProvider.new } ]
+
+        ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")
+        ActiveRecord::Migration.verbose = false
+        ActiveRecord::Schema.define(version: 1) do
+          create_table :posts do |t|
+            t.string :content
+          end
+        end
+
+        ActiveRecord::Base.connection.schema_cache.add("posts")
+      RUBY
+
+      app "production"
+
+      assert_kind_of ::MyOldKeyProvider, Post.attribute_types["content"].previous_schemes.first&.key_provider
+      assert_kind_of ::MyCustomKeyProvider, Post.attribute_types["content"].scheme.key_provider
+      assert_equal "dummy_key", Post.attribute_types["content"].scheme.key_provider.primary_key
+    end
+
     test "ActiveStorage.routes_prefix can be configured via config.active_storage.routes_prefix" do
       app_file "config/environments/development.rb", <<-RUBY
         Rails.application.configure do