Purge Bunny.net CDN on release (#43)

* Create release phase command

* Create rake task to purge cache

* Skip for review apps

Procfile

@@ -1 +1,2 @@
-web: bin/bridgetown start
+web: bin/bridgetown start
+release: rake cache:purge

Rakefile

@@ -1,4 +1,8 @@
 require "bridgetown"
+require 'uri'
+require 'net/http'
+require 'openssl'
+require 'dotenv/tasks'
 
 Bridgetown.load_tasks
 
@@ -37,6 +41,31 @@ namespace :frontend do
   end
 end
 
+namespace :cache do
+  desc "Purge Bunny.net CDN cache"
+  task :purge => :dotenv do
+    puts "Purging the CDN cache"
+
+    if ENV['REVIEW'] != 'true'
+      url = URI("https://api.bunny.net/pullzone/#{ENV['BUNNY_ZONE_ID']}/purgeCache")
+
+      http = Net::HTTP.new(url.host, url.port)
+      http.use_ssl = true
+
+      request = Net::HTTP::Post.new(url)
+      request["AccessKey"] = ENV['BUNNY_API_KEY']
+
+      response = http.request(request)
+      if response.code != "204"
+        raise "Unexpected response from CDN. Expected 204, got #{response.code}\n Response body: #{response.body}"
+      end
+      puts "Cache purged"
+    else
+      puts "Skipping. In review app."
+    end
+  end
+end
+
 task "assets:precompile" do
   Rake::Task[:deploy].invoke
 end