Initial version of basic service worker

.gitignore

@@ -34,3 +34,4 @@
 
 # Add back any keep files that might have been excluded by the above
 !.keep
+node_modules

Gemfile

@@ -34,7 +34,7 @@ gem 'jbuilder'
 gem 'paperclip', '~> 5.3'
 gem 'maxminddb'
 gem 'redcarpet'
-
+gem 'serviceworker-rails'
 gem 'aws-sdk', '~> 2.0'
 
 group :development, :test do

Gemfile.lock

@@ -97,8 +97,8 @@ GEM
     database_cleaner (1.6.2)
     delayed-web (0.4.4)
       rails (>= 3.2.13)
-    delayed_job (4.1.3)
-      activesupport (>= 3.0, < 5.2)
+    delayed_job (4.1.5)
+      activesupport (>= 3.0, < 5.3)
     delayed_job_active_record (4.1.2)
       activerecord (>= 3.0, < 5.2)
       delayed_job (>= 3.0, < 5)
@@ -266,6 +266,8 @@ GEM
       tilt (>= 1.1, < 3)
     scrypt (3.0.5)
       ffi-compiler (>= 1.0, < 2.0)
+    serviceworker-rails (0.5.5)
+      railties (>= 3.1)
     shoulda-matchers (3.1.2)
       activesupport (>= 4.0.0)
     slack-notifier (2.3.1)
@@ -349,6 +351,7 @@ DEPENDENCIES
   redcarpet
   rspec-rails
   sass-rails (~> 5.0)
+  serviceworker-rails
   shoulda-matchers
   slack-notifier
   test_after_commit
@@ -359,4 +362,4 @@ DEPENDENCIES
   will_paginate
 
 BUNDLED WITH
-   1.16.6
+   1.17.2

app/assets/javascripts/serviceworker.js.erb

@@ -0,0 +1,32 @@
+/**
+ * Welcome to your Workbox-powered service worker!
+ *
+ * You'll need to register this file in your web app and you should
+ * disable HTTP caching for this file too.
+ * See https://goo.gl/nhQhGp
+ *
+ * The rest of the code is auto-generated. Please don't update this file
+ * directly; instead, make changes to your Workbox build configuration
+ * and re-run your build process.
+ * See https://goo.gl/2aRDsh
+ */
+
+importScripts("https://storage.googleapis.com/workbox-cdn/releases/4.1.1/workbox-sw.js");
+
+workbox.core.skipWaiting();
+
+workbox.core.clientsClaim();
+
+/**
+ * The workboxSW.precacheAndRoute() method efficiently caches and responds to
+ * requests for URLs in the manifest.
+ * See https://goo.gl/S9QRab
+ */
+self.__precacheManifest = [].concat(self.__precacheManifest || []);
+workbox.precaching.precacheAndRoute(self.__precacheManifest, {});
+
+workbox.routing.registerRoute(/.*.html/, new workbox.strategies.NetworkOnly({ "cacheName":"parliament-petitions-html-cache-", plugins: [] }), 'GET');
+workbox.routing.registerRoute(/https:\/\/www.(?:googletagmanager|google-analytics).com\/(.*)/, new workbox.strategies.NetworkOnly({ "cacheName":"parliament-petitions-analytics-cache-", plugins: [] }), 'GET');
+workbox.routing.registerRoute(/count.json/, new workbox.strategies.NetworkOnly({ "cacheName":"parliament-petitions-data-cache-", plugins: [] }), 'GET');
+workbox.routing.registerRoute(/.*.(?:css|js)/, new workbox.strategies.CacheFirst({ "cacheName":"parliament-petitions-application-cache-", plugins: [new workbox.expiration.Plugin({ maxAgeSeconds: 2592000, purgeOnQuotaError: false })] }), 'GET');
+workbox.routing.registerRoute(/.*.(?:png|jpg|jpeg|ico|gif)/, new workbox.strategies.CacheFirst({ "cacheName":"parliament-petitions-image-cache-", plugins: [new workbox.expiration.Plugin({ maxAgeSeconds: 2592000, purgeOnQuotaError: false })] }), 'GET');

app/views/application/_service_worker.html.erb

@@ -0,0 +1,9 @@
+<script type="module">
+import {Workbox} from 'https://storage.googleapis.com/workbox-cdn/releases/4.0.0/workbox-window.prod.mjs';
+
+if ('serviceWorker' in navigator) {
+  const wb = new Workbox('/serviceworker.js');
+
+  wb.register();
+}
+</script>

app/views/layouts/application.html.erb

@@ -59,5 +59,7 @@
         <%= javascript_include_tag 'character-counter' %>
       <% end %>
     <% end %>
+
+    <%= render 'application/service_worker' %>
   </body>
 </html>

config/initializers/assets.rb

@@ -21,3 +21,4 @@
 
 # Compress JavaScript assets.
 Rails.application.config.assets.js_compressor = :uglifier
+Rails.configuration.assets.precompile += %w[serviceworker.js]

config/initializers/serviceworker.rb

@@ -0,0 +1,25 @@
+Rails.application.configure do
+  config.serviceworker.routes.draw do
+    # map to assets implicitly
+    match "/serviceworker.js"
+
+    # Examples
+    #
+    # map to a named asset explicitly
+    # match "/proxied-serviceworker.js" => "nested/asset/serviceworker.js"
+    # match "/nested/serviceworker.js" => "another/serviceworker.js"
+    #
+    # capture named path segments and interpolate to asset name
+    # match "/captures/*segments/serviceworker.js" => "%{segments}/serviceworker.js"
+    #
+    # capture named parameter and interpolate to asset name
+    # match "/parameter/:id/serviceworker.js" => "project/%{id}/serviceworker.js"
+    #
+    # insert custom headers
+    # match "/header-serviceworker.js" => "another/serviceworker.js",
+    #   headers: { "X-Resource-Header" => "A resource" }
+    #
+    # anonymous glob exposes `paths` variable for interpolation
+    # match "/*/serviceworker.js" => "%{paths}/serviceworker.js"
+  end
+end

config/workbox-config.js

@@ -0,0 +1,57 @@
+module.exports = {
+    // output to an ERB file so can be consumed by 'serviceworker-rails' gem
+    swDest: 'app/assets/javascripts/serviceworker.js.erb',
+    // globbing only used for pre-caching
+    globDirectory: '.',
+    globPatterns: [],
+    // only allow caching of files under 1MB
+    maximumFileSizeToCacheInBytes: 1 * 1024 * 1024,
+    // use CDN version of WB (can also be local or disabled)
+    importWorkboxFrom: 'cdn',
+    // claim any browser tabs that are running immediately
+    clientsClaim: true,
+    // skip the wait and init immediately
+    skipWaiting: true,
+    // define custom caching routes for more flexibility
+    runtimeCaching: [
+        // HTML will always be served from the network
+        {
+            urlPattern: new RegExp('.*\.html'),
+            handler: 'NetworkOnly'
+        },
+        // Analytics always comes from the network
+        {
+            urlPattern: new RegExp('https://www.(?:googletagmanager|google-analytics).com/(.*)'),
+            handler: 'NetworkOnly'
+        },
+        // JSON file to update the counter always comes from the network
+        {
+            urlPattern: new RegExp('count.json'),
+            handler: 'NetworkOnly'
+        },
+        // CSS / JS assets using cache first strategy since filenames are revisioned
+        {
+            urlPattern: new RegExp('.*.(?:css|js)'),
+            handler: 'CacheFirst',
+            options: {
+                cacheName: 'parliament-petitions-application-cache-',
+                // assets only cached for 30 days ensuring older revisions clear out after this time
+                expiration: {
+                    maxAgeSeconds: 30 * 24 * 60 * 60
+                }
+            }
+        },
+        // Image assets using cache first strategy since filenames are revisioned
+        {
+            urlPattern: new RegExp('.*.(?:png|jpg|jpeg|ico|gif)'),
+            handler: 'CacheFirst',
+            options: {
+                cacheName: 'parliament-petitions-image-cache-',
+                // assets only cached for 30 days ensuring older revisions clear out after this time
+                expiration: {
+                    maxAgeSeconds: 30 * 24 * 60 * 60
+                }
+            }
+        }
+    ]
+};