Web IDE & CodeSandbox

This enables JavaScripts projects to have live previews straight in the
browser without requiring any local configuration. This uses the
CodeSandbox package `sandpack` to compile it all inside of an iframe.

This feature is off by default and can be toggled on in the admin
settings. Only projects with a `package.json` and a `main` key are
supported.

Updates happen in real-time with hot-reloading. We just watch for
changes to files and then send them to `sandpack` to allow it to reload
the iframe. The iframe includes a very simple navigation bar, the text
bar is `readonly` to stop users navigating away from the preview and
the back and forward buttons just pop/splice the navigation stack
which is tracked by a listener on `sandpack`

There is a button inside the iframe which allows the user to open the
projects inside of CodeSandbox. This button is only visible on
**public** projects. On private or internal projects this button
get hidden to protect private code being leaked into an external
public URL.

Closes #47268

2 files changed, 21 insertions, 0 deletions

diff --git a/db/migrate/20180723135214_add_web_ide_client_side_preview_enabled_to_application_settings.rb b/db/migrate/20180723135214_add_web_ide_client_side_preview_enabled_to_application_settings.rb
new file mode 100644
index 00000000000..1ebb91da00c
--- /dev/null
+++ b/db/migrate/20180723135214_add_web_ide_client_side_preview_enabled_to_application_settings.rb
@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+class AddWebIdeClientSidePreviewEnabledToApplicationSettings < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    add_column_with_default(:application_settings, :web_ide_clientside_preview_enabled,
+                            :boolean,
+                            default: false,
+                            allow_null: false)
+  end
+
+  def down
+    remove_column(:application_settings, :web_ide_clientside_preview_enabled)
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 30b8147a474..c132f787530 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -169,6 +169,7 @@ ActiveRecord::Schema.define(version: 20180726172057) do
     t.boolean "mirror_available", default: true, null: false
     t.boolean "hide_third_party_offers", default: false, null: false
     t.boolean "instance_statistics_visibility_private", default: false, null: false
+    t.boolean "web_ide_clientside_preview_enabled", default: false, null: false
   end
 
   create_table "audit_events", force: :cascade do |t|