Cache Appearance instances in Redisappearances-caching-and-schema

This caches the result of Appearance.first in a similar fashion to how
ApplicationSetting instances are cached. We also add some NOT NULL
constraints to the table and correct the timestamp types.

Fixes gitlab-org/gitlab-ce#36066, fixes gitlab-org/gitlab-ce#31698

2 files changed, 37 insertions, 4 deletions

diff --git a/db/migrate/20170809142252_cleanup_appearances_schema.rb b/db/migrate/20170809142252_cleanup_appearances_schema.rb
new file mode 100644
index 00000000000..90d12925ba2
--- /dev/null
+++ b/db/migrate/20170809142252_cleanup_appearances_schema.rb
@@ -0,0 +1,33 @@
+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class CleanupAppearancesSchema < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  # Set this constant to true if this migration requires downtime.
+  DOWNTIME = false
+
+  NOT_NULL_COLUMNS = %i[title description description_html created_at updated_at]
+
+  TIME_COLUMNS = %i[created_at updated_at]
+
+  def up
+    NOT_NULL_COLUMNS.each do |column|
+      change_column_null :appearances, column, false
+    end
+
+    TIME_COLUMNS.each do |column|
+      change_column :appearances, column, :datetime_with_timezone
+    end
+  end
+
+  def down
+    NOT_NULL_COLUMNS.each do |column|
+      change_column_null :appearances, column, true
+    end
+
+    TIME_COLUMNS.each do |column|
+      change_column :appearances, column, :datetime # rubocop: disable Migration/Datetime
+    end
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index ed3cf70bcdd..ec92b185be2 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20170807160457) do
+ActiveRecord::Schema.define(version: 20170809142252) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -28,13 +28,13 @@ ActiveRecord::Schema.define(version: 20170807160457) do
   end
 
   create_table "appearances", force: :cascade do |t|
-    t.string "title"
-    t.text "description"
+    t.string "title", null: false
+    t.text "description", null: false
     t.string "header_logo"
     t.string "logo"
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
-    t.text "description_html"
+    t.text "description_html", null: false
     t.integer "cached_markdown_version"
   end