Support passing revision as query string param

[mikeys]

Currently, It's not possible to pass a revision as a query string param to the EmberController, in order to load a different index.html (based on the revision).

This can be a very helpful feature, in order to be able to assert that a version you've just deployed is working correctly in production, before actually releasing ('activating') it.

However, I couldn't figure out an elegant way of solving this without altering code in both ember-cli-rails-deploy-redis AND ember-cli-rails. Would love to hear your input:

From ember-cli-rails gem source, app/helpers/ember_rails_helper.rb:

module EmberRailsHelper
  def render_ember_app(name, &block)
    EmberCli[name].build

    markup_capturer = HtmlPage::Capture.new(self, &block)

    head, body = markup_capturer.capture

    render inline: EmberCli[name].index_html(head: head, body: body)
  end
end

render_ember_app is being called from the main ember view, which then calls EmberCli::App's instance index_html method, passing head and body params.

EmberCli::App#index_html method looks like this:

    def index_html(head:, body:)
      html = HtmlPage::Renderer.new(
        head: head,
        body: body,
        content: deploy.index_html,
      )

      html.render
    end

That means that the actual deploy instance (In this case, an instance of EmberCli::Deploy::Redis) cannot receive additional options (like revision from the request params) on index_html.

A relatively easy solution would be to pass the request context to App#index_html as part of EmberRailsHelper#render_ember_app which in turn will forward it to Deploy#index_html.

Then in ember-cli-rails-deploy-redis
EmberCli::Deploy::Redis#index_html we can do something like this:

def index_html(request)
  revision = request.params[:revision]
  redis_client.get(deploy_key(revision: revision)).presence || index_html_missing!
end

Would love to hear a better solution...