From 18b0107e506e76cc5d4928297889150ad4f35689 Mon Sep 17 00:00:00 2001
From: Darren Cauthon <darren@cauthon.com>
Date: Sun, 3 Jan 2016 19:58:12 -0600
Subject: [PATCH] Add the http status agent.

---
 app/concerns/web_request_concern.rb           |   4 +-
 app/models/agents/http_status_agent.rb        |  81 ++++++
 spec/controllers/http_status_agent_spec.rb    | 260 ++++++++++++++++++
 .../shared_examples/web_request_concern.rb    |  11 +
 4 files changed, 355 insertions(+), 1 deletion(-)
 create mode 100644 app/models/agents/http_status_agent.rb
 create mode 100644 spec/controllers/http_status_agent_spec.rb

diff --git a/app/concerns/web_request_concern.rb b/app/concerns/web_request_concern.rb
index 756f6dbc..ef6adc4a 100644
--- a/app/concerns/web_request_concern.rb
+++ b/app/concerns/web_request_concern.rb
@@ -110,7 +110,9 @@ module WebRequestConcern
 
       builder.headers[:user_agent] = user_agent
 
-      builder.use FaradayMiddleware::FollowRedirects
+      unless boolify(interpolated['disable_redirect_follow'])
+        builder.use FaradayMiddleware::FollowRedirects
+      end
       builder.request :url_encoded
 
       if boolify(interpolated['disable_url_encoding'])
diff --git a/app/models/agents/http_status_agent.rb b/app/models/agents/http_status_agent.rb
new file mode 100644
index 00000000..780afdaa
--- /dev/null
+++ b/app/models/agents/http_status_agent.rb
@@ -0,0 +1,81 @@
+module Agents
+
+  class HttpStatusAgent < Agent
+
+    include WebRequestConcern
+    include FormConfigurable
+
+    can_dry_run!
+    can_order_created_events!
+
+    default_schedule "every_12h"
+
+    form_configurable :url
+    form_configurable :disable_redirect_follow, type: :array, values: ['true', 'false']
+
+    description <<-MD
+      The HttpStatusAgent will check a url and emit the resulting HTTP status code.
+
+      Specify a `Url` and the Http Status Agent will produce an event with the http status code.
+
+      The `disable redirect follow` option causes the Agent to not follow HTTP redirects. For example, setting this to `true` will cause an agent that receives a 301 redirect to `http://yahoo.com` to return a status of 301 instead of following the redirect and returning 200.
+    MD
+
+    event_description <<-MD
+      Events will have the following fields:
+
+          {
+            "url": "...",
+            "status": "..."
+          }
+    MD
+
+    def working?
+      memory['last_status'].to_i > 0
+    end
+
+    def default_options
+      {
+        'url' => "http://google.com",
+        'disable_redirect_follow' => "true",
+      }
+    end
+
+    def validate_options
+      errors.add(:base, "a url must be specified") unless options['url'].present?
+    end
+
+    def check
+      check_this_url interpolated[:url]
+    end
+
+    def receive(incoming_events)
+      incoming_events.each do |event|
+        interpolate_with(event) do
+          check_this_url interpolated[:url]
+        end
+      end
+    end
+
+    private
+
+    def check_this_url(url)
+      if result = ping(url)
+        create_event payload: { 'url' => url, 'status' => result.status.to_s, 'response_received' => true }
+        memory['last_status'] = result.status.to_s
+      else
+        create_event payload: { 'url' => url, 'response_received' => false }
+        memory['last_status'] = nil
+      end
+    end
+
+    def ping(url)
+      result = faraday.get url
+      result.status > 0 ? result : nil
+    rescue
+      nil
+    end
+
+  end
+
+end
diff --git a/spec/controllers/http_status_agent_spec.rb b/spec/controllers/http_status_agent_spec.rb
new file mode 100644
index 00000000..a78fa495
--- /dev/null
+++ b/spec/controllers/http_status_agent_spec.rb
@@ -0,0 +1,260 @@
+require 'rails_helper'
+
+describe 'HttpStatusAgent' do
+
+  let(:agent) do
+    Agents::HttpStatusAgent.new(:name => SecureRandom.uuid, :options => valid_params).tap do |a|
+      a.service = services(:generic)
+      a.user = users(:jane)
+      a.options['url'] = 'http://google.com'
+      a.save!
+
+      def a.interpolate_with(e, &block)
+        @the_event = e
+        block.call
+      end
+
+      def a.interpolated
+        @the_event.payload
+      end
+
+      def a.create_event event
+        @the_created_events ||= []
+        @the_created_events << event
+      end
+
+      def a.the_created_events
+        @the_created_events || []
+      end
+
+      def a.faraday
+        @faraday ||= Struct.new(:programmed_responses).new({}).tap do |f|
+                       def f.get url
+                         programmed_responses[url] || raise('invalid url')
+                       end
+
+                       def f.set url, response, time = nil
+                         sleep(time/1000) if time
+                         programmed_responses[url] = response
+                       end
+                     end
+      end
+    end
+  end
+
+  let(:valid_params) { {} }
+
+  describe "working" do
+    it "should be working when the last status is 200" do
+      agent.memory['last_status'] = '200'
+      expect(agent.working?).to eq(true)
+    end
+
+    it "should be working when the last status is 304" do
+      agent.memory['last_status'] = '304'
+      expect(agent.working?).to eq(true)
+    end
+
+    it "should not be working if the status is 0" do
+      agent.memory['last_status'] = '0'
+      expect(agent.working?).to eq(false)
+    end
+
+    it "should not be working if the status is missing" do
+      agent.memory['last_status'] = nil
+      expect(agent.working?).to eq(false)
+    end
+
+    it "should not be working if the status is -1" do
+      agent.memory['last_status'] = '-1'
+      expect(agent.working?).to eq(false)
+    end
+  end
+
+  describe "check" do
+
+    before do
+
+      def agent.interpolated
+        @interpolated ||= { :url => SecureRandom.uuid }
+      end
+
+      def agent.check_this_url url
+        @url = url
+      end
+
+      def agent.checked_url
+        @url
+      end
+
+    end
+
+    it "should check the url" do
+      agent.check
+      expect(agent.checked_url).to eq(agent.interpolated[:url])
+    end
+
+  end
+
+  describe "receive" do
+
+    describe "with an event with a successful ping" do
+
+      let(:successful_url) { SecureRandom.uuid }
+
+      let(:status_code) { 200 }
+
+      let(:event_with_a_successful_ping) do
+        agent.faraday.set(successful_url, Struct.new(:status).new(status_code))
+        Event.new.tap { |e| e.payload = { url: successful_url } }
+      end
+
+      let(:events) do
+        [event_with_a_successful_ping]
+      end
+
+      it "should create one event" do
+        agent.receive events
+        expect(agent.the_created_events.count).to eq(1)
+      end
+
+      it "should note that the successful response succeeded" do
+        agent.receive events
+        expect(agent.the_created_events[0][:payload]['response_received']).to eq(true)
+      end
+
+      it "should return the status code" do
+        agent.receive events
+        expect(agent.the_created_events[0][:payload]['status']).to eq('200')
+      end
+
+      it "should remember the status" do
+        agent.receive events
+        expect(agent.memory['last_status']).to eq('200')
+      end
+
+      describe "but the status code is not 200" do
+        let(:status_code) { 500 }
+
+        it "should return the status code" do
+          agent.receive events
+          expect(agent.the_created_events[0][:payload]['status']).to eq('500')
+        end
+
+        it "should remember the status" do
+          agent.receive events
+          expect(agent.memory['last_status']).to eq('500')
+        end
+      end
+
+      it "should return the original url" do
+        agent.receive events
+        expect(agent.the_created_events[0][:payload]['url']).to eq(successful_url)
+      end
+
+      describe "but the ping returns a status code of 0" do
+
+        let(:event_with_a_successful_ping) do
+          agent.faraday.set(successful_url, Struct.new(:status).new(0))
+          Event.new.tap { |e| e.payload = { url: successful_url } }
+        end
+
+        it "should create one event" do
+          agent.receive events
+          expect(agent.the_created_events.count).to eq(1)
+        end
+
+        it "should note that no response was received" do
+          agent.receive events
+          expect(agent.the_created_events[0][:payload]['response_received']).to eq(false)
+        end
+
+        it "should return the original url" do
+          agent.receive events
+          expect(agent.the_created_events[0][:payload]['url']).to eq(successful_url)
+        end
+
+        it "should remember no status" do
+          agent.memory['last_status'] = '200'
+          agent.receive events
+          expect(agent.memory['last_status']).to be_nil
+        end
+
+      end
+
+      describe "but the ping returns a status code of -1" do
+
+        let(:event_with_a_successful_ping) do
+          agent.faraday.set(successful_url, Struct.new(:status).new(-1))
+          Event.new.tap { |e| e.payload = { url: successful_url } }
+        end
+
+        it "should create one event" do
+          agent.receive events
+          expect(agent.the_created_events.count).to eq(1)
+        end
+
+        it "should note that no response was received" do
+          agent.receive events
+          expect(agent.the_created_events[0][:payload]['response_received']).to eq(false)
+        end
+
+        it "should return the original url" do
+          agent.receive events
+          expect(agent.the_created_events[0][:payload]['url']).to eq(successful_url)
+        end
+
+      end
+
+      describe "and with one event with a failing ping" do
+
+        let(:failing_url)    { SecureRandom.uuid }
+        let(:event_with_a_failing_ping)    { Event.new.tap { |e| e.payload = { url: failing_url } } }
+
+        let(:events) do
+          [event_with_a_successful_ping, event_with_a_failing_ping]
+        end
+
+        it "should create two events" do
+          agent.receive events
+          expect(agent.the_created_events.count).to eq(2)
+        end
+
+        it "should note that the failed response failed" do
+          agent.receive events
+          expect(agent.the_created_events[1][:payload]['response_received']).to eq(false)
+        end
+
+        it "should note that the successful response succeeded" do
+          agent.receive events
+          expect(agent.the_created_events[0][:payload]['response_received']).to eq(true)
+        end
+
+        it "should return the original url on both events" do
+          agent.receive events
+          expect(agent.the_created_events[0][:payload]['url']).to eq(successful_url)
+          expect(agent.the_created_events[1][:payload]['url']).to eq(failing_url)
+        end
+
+      end
+
+    end
+
+    describe "validations" do
+      before do
+        expect(agent).to be_valid
+      end
+
+      it "should validate url" do
+        agent.options['url'] = ""
+        expect(agent).not_to be_valid
+
+        agent.options['url'] = "http://www.google.com"
+        expect(agent).to be_valid
+      end
+    end
+
+  end
+
+
+end
diff --git a/spec/support/shared_examples/web_request_concern.rb b/spec/support/shared_examples/web_request_concern.rb
index fd0612c0..8fc0b2ec 100644
--- a/spec/support/shared_examples/web_request_concern.rb
+++ b/spec/support/shared_examples/web_request_concern.rb
@@ -156,6 +156,17 @@ shared_examples_for WebRequestConcern do
       agent.options['disable_url_encoding'] = 'true'
       expect(agent.faraday.options.params_encoder).to eq(WebRequestConcern::DoNotEncoder)
     end
+
+    describe "redirect follow" do
+      it "should use FollowRedirects by default" do
+        expect(agent.faraday.builder.handlers).to include(FaradayMiddleware::FollowRedirects)
+      end
+
+      it "should not use FollowRedirects when disabled" do
+        agent.options['disable_redirect_follow'] = true
+        expect(agent.faraday.builder.handlers).not_to include(FaradayMiddleware::FollowRedirects)
+      end
+    end
   end
 
   describe WebRequestConcern::DoNotEncoder do