Use rack-cache

Gemfile

@@ -8,6 +8,7 @@ gem 'fixer'
 gem 'kgio'
 gem 'newrelic_rpm'
 gem 'oj'
+gem 'rack-cache'
 gem 'rack-cors'
 gem 'rake'
 gem 'sequel_pg'

Gemfile.lock

@@ -21,6 +21,8 @@ GEM
       method_source (~> 0.8.1)
       slop (~> 3.4)
     rack (1.6.5)
+    rack-cache (1.6.1)
+      rack (>= 0.4)
     rack-cors (0.4.0)
     rack-protection (1.5.3)
       rack
@@ -65,6 +67,7 @@ DEPENDENCIES
   newrelic_rpm
   oj
   pry
+  rack-cache
   rack-cors
   rack-test
   rake

config/app.rb

@@ -1,12 +1,10 @@
 # frozen_string_literal: true
-
-require 'dalli'
 require 'pathname'
 
 # Encapsulates app configuration
 module App
   class << self
-    attr_reader :cache, :version, :released_at
+    attr_reader :version
 
     def env
       ENV['RACK_ENV'] || 'development'
@@ -17,7 +15,5 @@ module App
     end
   end
 
-  @cache = Dalli::Client.new
-  @released_at = `git show -s --format=%ci HEAD`
   @version = `git rev-parse --short HEAD 2>/dev/null`.strip!
 end

lib/api.rb

@@ -1,11 +1,22 @@
 # frozen_string_literal: true
-
+require 'dalli'
 require 'oj'
 require 'sinatra'
+require 'rack/cache'
 require 'rack/cors'
 require 'quote'
 
-set :cache_ttl, 900 # 15 minutes
+use Rack::Cache,
+    verbose: true,
+    metastore: "memcached://#{ENV['MEMCACHE_SERVERS']}/meta",
+    entitystore: "memcached://#{ENV['MEMCACHE_SERVERS']}/body"
+
+use Rack::Cors do
+  allow do
+    origins '*'
+    resource '*', headers: :any, methods: :get
+  end
+end
 
 configure :development do
   set :show_exceptions, :after_handler
@@ -46,46 +57,30 @@ helpers do
   def encode_json(data)
     Oj.dump(data, mode: :compat)
   end
-
-  def cache
-    App.cache.fetch request.fullpath, settings.cache_ttl do
-      yield
-    end
-  end
-end
-
-use Rack::Cors do
-  allow do
-    origins '*'
-    resource '*', headers: :any, methods: :get
-  end
 end
 
 options '*' do
   200
 end
 
-before do
-  content_type 'application/json'
+get '*' do
+  cache_control :public, :must_revalidate, max_age: 900
+  pass
 end
 
 get '/' do
-  last_modified App.released_at
+  etag App.version
   jsonp details: 'http://fixer.io', version: App.version
 end
 
 get '/latest' do
-  cache do
-    last_modified quote_attributes[:date]
+  last_modified quote.date
   jsonp quote_attributes
-  end
 end
 
 get(/(?<date>\d{4}-\d{2}-\d{2})/) do
-  cache do
-    last_modified quote_attributes[:date]
+  last_modified quote.date
   jsonp quote_attributes
-  end
 end
 
 not_found do

spec/api_spec.rb

@@ -1,5 +1,4 @@
 # frozen_string_literal: true
-
 require_relative 'helper'
 require 'rack/test'
 require 'api'
@@ -12,7 +11,7 @@ describe 'the API' do
   let(:headers) { last_response.headers }
 
   before do
-    App.cache.flush
+    Dalli::Client.new.flush
   end
 
   it 'describes itself' do
@@ -61,13 +60,25 @@ describe 'the API' do
     json['rates'].wont_be :empty?
   end
 
-  it 'returns a last modified header' do
+  it 'returns a cache control header' do
     %w(/ /latest /2012-11-20).each do |path|
+      get path
+      headers['Cache-Control'].wont_be_nil
+    end
+  end
+
+  it 'returns a last modified header' do
+    %w(/latest /2012-11-20).each do |path|
       get path
       headers['Last-Modified'].wont_be_nil
     end
   end
 
+  it 'returns an etag header' do
+    get '/'
+    headers['ETag'].wont_be_nil
+  end
+
   it 'allows cross-origin requests' do
     %w(/ /latest /2012-11-20).each do |path|
       header 'Origin', '*'
@@ -91,12 +102,6 @@ describe 'the API' do
     json['rates']['USD'].must_be :>, 100
   end
 
-  it 'caches quotes' do
-    App.cache.set '/latest', 'foo'
-    get '/latest'
-    last_response.body.must_equal 'foo'
-  end
-
   it 'sets Content-Type header to JSON when caching' do
     2.times do
       get '/latest'

spec/edge_cases_spec.rb

@@ -1,5 +1,4 @@
 # frozen_string_literal: true
-
 require_relative 'helper'
 require 'rack/test'
 require 'api'
@@ -11,7 +10,7 @@ describe 'the API' do
   let(:json) { Oj.load(last_response.body) }
 
   before do
-    App.cache.flush
+    Dalli::Client.new.flush
   end
 
   it 'handles unfound pages' do