Allow Nginx cached static content to be purged (#9857) [deploy]

* Only bust_fastly_cache if fastly is enabled

* Conditionally bust nginx cache from CacheBuster#bust

* Don't _actually_ call out to openresty

* Remove redundant check for FASTLY_API_KEY in CacheBuster

* Clean up and add a spec

* Do not call .purge_ methods if fastly is not configured

* Add OPENRESTY_ ENV vars to .env_sample

* Remove extra / prepending path

* Remove ConfigurationError, clean up Purgeable concern

* Use raise instead of fail like fastly-ruby

* No longer check for Rails.env.production?

* Use let! to create article in BustMultipleCachesWorker spec

.env_sample

@@ -2,6 +2,10 @@
 export APP_DOMAIN="localhost:3000"
 export APP_PROTOCOL="http://"
 
+# Openresty domain + Protocol setting for development
+export OPENRESTY_DOMAIN=""
+export OPENRESTY_PROTOCOL=""
+
 # Community Related Variables
 export COMMUNITY_NAME="DEV(local)"
 

app/labor/cache_buster.rb

@@ -18,18 +18,49 @@ module CacheBuster
     # fastly.purge(path)
     #
     # https://github.com/fastly/fastly-ruby#efficient-purging
-    return unless Rails.env.production?
-    return if ApplicationConfig["FASTLY_API_KEY"].blank?
-
-    HTTParty.post("https://api.fastly.com/purge/https://#{ApplicationConfig['APP_DOMAIN']}#{path}",
-                  headers: { "Fastly-Key" => ApplicationConfig["FASTLY_API_KEY"] })
-    HTTParty.post("https://api.fastly.com/purge/https://#{ApplicationConfig['APP_DOMAIN']}#{path}?i=i",
-                  headers: { "Fastly-Key" => ApplicationConfig["FASTLY_API_KEY"] })
+    if fastly_enabled?
+      bust_fastly_cache(path)
+    elsif nginx_enabled?
+      bust_nginx_cache(path)
+    end
   rescue URI::InvalidURIError => e
     Rails.logger.error("Trying to bust cache of an invalid uri: #{e}")
     DatadogStatsClient.increment("cache_buster.invalid_uri", tags: ["path:#{path}"])
   end
 
+  def self.fastly_enabled?
+    ApplicationConfig["FASTLY_API_KEY"].present? && ApplicationConfig["FASTLY_SERVICE_ID"].present?
+  end
+
+  def self.nginx_enabled?
+    ApplicationConfig["OPENRESTY_PROTOCOL"].present? && ApplicationConfig["OPENRESTY_DOMAIN"].present?
+  end
+
+  def self.bust_fastly_cache(path)
+    HTTParty.post(
+      "https://api.fastly.com/purge/https://#{ApplicationConfig['APP_DOMAIN']}#{path}",
+      headers: {
+        "Fastly-Key" => ApplicationConfig["FASTLY_API_KEY"]
+      },
+    )
+    HTTParty.post(
+      "https://api.fastly.com/purge/https://#{ApplicationConfig['APP_DOMAIN']}#{path}?i=i",
+      headers: {
+        "Fastly-Key" => ApplicationConfig["FASTLY_API_KEY"]
+      },
+    )
+  end
+
+  def self.bust_nginx_cache(path)
+    uri = URI.parse("#{ApplicationConfig['OPENRESTY_PROTOCOL']}#{ApplicationConfig['OPENRESTY_DOMAIN']}#{path}")
+    http = Net::HTTP.new(uri.host, uri.port)
+    response = http.request Net::HTTP::NginxPurge.new(uri.request_uri)
+
+    raise StandardError, "NginxPurge request failed: #{response.body}" unless response.is_a?(Net::HTTPSuccess)
+
+    response.body
+  end
+
   def self.bust_comment(commentable)
     return unless commentable
 
@@ -206,3 +237,12 @@ module CacheBuster
     end
   end
 end
+
+# Creates our own purge method for an HTTP request,
+# which is used by Nginx to bust a cache.
+# See Net::HTTPGenericRequest for attributes/methods.
+class Net::HTTP::NginxPurge < Net::HTTPRequest # rubocop:disable Style/ClassAndModuleChildren
+  METHOD = "PURGE".freeze
+  REQUEST_HAS_BODY = false
+  RESPONSE_HAS_BODY = true
+end

app/models/article.rb

@@ -645,8 +645,6 @@ class Article < ApplicationRecord
   end
 
   def bust_cache
-    return unless Rails.env.production?
-
     CacheBuster.bust(path)
     CacheBuster.bust("#{path}?i=i")
     CacheBuster.bust("#{path}?preview=#{password}")

app/models/concerns/purgeable.rb

@@ -1,19 +1,20 @@
 # Copied from the deprecated fastly-rails gem
 # https://github.com/fastly/fastly-rails/blob/master/lib/fastly-rails/active_record/surrogate_key.rb
 #
-# This concern handles purge and purge_all calls to purge the edge cache (Fastly)
+# This concern handles purge and purge_all calls to purge Fastly's edge cache.
+# If Fastly has not been configured, these methods will short circuit and not be invoked.
 module Purgeable
   extend ActiveSupport::Concern
 
   module ClassMethods
     def purge_all
-      return if Rails.env.development?
+      return unless fastly
 
       service.purge_by_key(table_key)
     end
 
     def soft_purge_all
-      return if Rails.env.development?
+      return unless fastly
 
       service.purge_by_key(table_key, true)
     end
@@ -23,13 +24,14 @@ module Purgeable
     end
 
     def fastly
-      return if Rails.env.development?
+      return false if Rails.env.development?
+      return false if ApplicationConfig["FASTLY_API_KEY"].blank? || ApplicationConfig["FASTLY_SERVICE_ID"].blank?
 
       Fastly.new(api_key: ApplicationConfig["FASTLY_API_KEY"])
     end
 
     def service
-      return if Rails.env.development?
+      return unless fastly
 
       Fastly::Service.new({ id: ApplicationConfig["FASTLY_SERVICE_ID"] }, fastly)
     end
@@ -45,13 +47,13 @@ module Purgeable
   end
 
   def purge
-    return if Rails.env.development?
+    return unless fastly
 
     service.purge_by_key(record_key)
   end
 
   def soft_purge
-    return if Rails.env.development?
+    return unless fastly
 
     service.purge_by_key(record_key, true)
   end

spec/labor/cache_buster_spec.rb

@@ -11,6 +11,31 @@ RSpec.describe CacheBuster, type: :labor do
   let(:podcast_episode) { create(:podcast_episode, podcast_id: podcast.id) }
   let(:tag) { create(:tag) }
 
+  describe "#bust_nginx_cache" do
+    before do
+      allow(cache_buster).to receive(:bust_nginx_cache).and_call_original
+      allow(ApplicationConfig).to receive(:[]).with("OPENRESTY_PROTOCOL").and_return("http://")
+      allow(ApplicationConfig).to receive(:[]).with("OPENRESTY_DOMAIN").and_return("localhost:9090")
+    end
+
+    it "can bust an nginx cache when configured" do
+      cache_buster.bust_nginx_cache("/#{user.username}")
+    end
+  end
+
+  describe "#bust_fastly_cache" do
+    before do
+      allow(cache_buster).to receive(:bust_fastly_cache).and_call_original
+      allow(ApplicationConfig).to receive(:[]).with("APP_DOMAIN").and_return("fake-key")
+      allow(ApplicationConfig).to receive(:[]).with("FASTLY_API_KEY").and_return("fake-key")
+      allow(ApplicationConfig).to receive(:[]).with("FASTLY_SERVICE_ID").and_return("localhost:3000")
+    end
+
+    it "can bust a fastly cache when configured" do
+      cache_buster.bust_fastly_cache("/#{user.username}")
+    end
+  end
+
   describe "#bust_comment" do
     it "busts comment" do
       cache_buster.bust_comment(comment.commentable)

spec/models/concerns/purgeable_spec.rb

@@ -18,6 +18,8 @@ RSpec.describe Purgeable do
   let(:fastly_service) { instance_double(Fastly::Service) }
 
   before do
+    allow(ApplicationConfig).to receive(:[]).with("FASTLY_API_KEY").and_return("fake-key")
+    allow(ApplicationConfig).to receive(:[]).with("FASTLY_SERVICE_ID").and_return("fake-service-id")
     allow(Fastly::Service).to receive(:new).and_return(fastly_service)
   end
 

spec/rails_helper.rb

@@ -139,6 +139,9 @@ RSpec.configure do |config|
     stub_request(:post, /api.fastly.com/)
       .to_return(status: 200, body: "".to_json, headers: {})
 
+    stub_request(:any, /localhost:9090/)
+      .to_return(status: 200, body: "OK".to_json, headers: {})
+
     stub_request(:post, /api.bufferapp.com/)
       .to_return(status: 200, body: { fake_text: "so fake" }.to_json, headers: {})
 

spec/workers/articles/bust_multiple_caches_worker_spec.rb

@@ -2,7 +2,9 @@ require "rails_helper"
 
 RSpec.describe Articles::BustMultipleCachesWorker, type: :worker do
   describe "#perform" do
-    let(:article) { create(:article) }
+    # Explicitly create article before the test is invoked, since
+    # creating an article will invoke CacheBuster#bust in a callback.
+    let!(:article) { create(:article) }
     let(:path) { article.path }
     let(:worker) { subject }