Livereload and Hanami
2 min read August 05, 2016 hanami, livereload, ruby

I’ve spent a lot of time trying to figure out how to make LiveReload work in Hanami.

Installing LiveReload

Add that to your Gemfile:

gem 'guard'
gem 'guard-livereload', '~> 2.5', require: false
gem 'rack-livereload' # if you don't want to use browser extension

Then run bundle install.

Preparing Guard for watching our files

By default, guard-livereload is targeted for RoR. We should change Guardfile to:

guard 'livereload' do
  extensions = {
    css: :css,
    scss: :css,
    sass: :css,
    js: :js,
    coffee: :js,
    html: :html,
    png: :png,
    gif: :gif,
    jpg: :jpg,
    jpeg: :jpeg,
    # less: :less, # uncomment if you want LESS stylesheets done in browser

  extensions.each do |ext, type|
          (?:apps) # /apps/
          (?:/\w+/assets/\w+/(?<path>[^.]+) # /apps/<app_name>/assets/<folder>/<file>
           (?<ext>\.#{ext})) # matching extension (must be first encountered)
          (?:\.\w+|$) # other extensions
          }x) do |m|
      path = m[1]
      "/assets/#{path}.#{type}" # Hanami puts compiled assets in development env here

This config make Guard watch for ./apps/<app_name>/assets/<folder>/<file>. Once something will be changed there, guard-livereload will sent a RELOAD signal to our browser: RELOAD /assets/<file>.

Enabling LiveReload

Browser extension (preferred)

Install the corresponding extension for your browser:

You can find more ways to install it on the official website.

Rack gem

Add this code to / before run

require 'rack-livereload'
use Rack::LiveReload

This will enable rack-livereload globally.

Fixing Content Security Policy

If you run guard and hanami server and try to open your site, you’ll see Content Security Policy error in your console. The problem here is guard will host it’s own livereload.js at localhost:35729 and rack-livereload will be trying to inject it. But hanami does not allow including scripts and connecting to WebSockets from external resources.

We’ll change CSP to allow loading inline scripts and scripts from localhost:35729.

Change security.content_security_policy %{...} in apps/<app>/application.rb to:

security.content_security_policy %{
  script-src 'self' http://localhost:35729/ 'unsafe-inline';
  connect-src 'self' ws://localhost:35729/;

We allowed inline scripts because rack-livereload injects some variables in this way for livereload.js (such as RACK_LIVERELOAD_PORT and WEB_SOCKET_SWF_LOCATION).

We allowed scripts from localhost:35729 and connections to localhost:35729. livereload.js will be trying to connect to ws://localhost:35729. That’s why we allow to do it in CSP.

Testing LiveReload

Run guard and hanami server. Open localhost:2300 and change any resource (a css file for example). Your changes should be applied immediately.

If you’re using the extension for browser, don’t forget to connect to the livereload server by clicking on the toolbar button.

Have fun! :)

Archieved post