It seems view layouts from engines where the controller is also present in the host app do not load in production, but load fine in development.

Example

Github Repo

working

1. ./script/server
2. browse to http://localhost:3000/index

not working

1. ./script/server -e production
2. browse to http://localhost:3000/index

Explanation

Host Application

app/controller/application_controller.rb app/views/layouts/ {empty} app/views/other_controller/index.html.haml

%p content of app/view/other_controller/index.html.haml

Engine

vender/plugins/engine_name/app/controller/application_controller.rb vender/plugins/engine_name/app/controller/other_controller.rb

class OtherController < ApplicationController
...
end

vender/plugins/engine_name/app/views/layouts/application.html.haml

%h1 ApplicationController layouts content
= yield

HTML output in production

does not render the layouts

<p> content of app/view/other_controller/index.html.haml

HTML output in development

renders the layouts

<h1> ApplicationController layouts content</h1>
<p> content of app/view/other_controller/index.html.haml