Merge pull request #161 from alphagov/new-healthchecks

Add a couple of new healthchecks

CHANGELOG.md

@@ -1,3 +1,8 @@
+# 2.4.0
+
+* Add new GovukHealthcheck::Mongoid check
+* Add new GovukHealthcheck::RailsCache check
+
 # 2.3.0
 
 * Remove unused SidekiqQueueSizeCheck healthcheck base class

docs/healthchecks.md

@@ -73,6 +73,15 @@ if it must be subclassed to work, but a concrete class which works on its own
 doesn't need that suffix. You should aim to follow this convention in your own
 apps, ideally putting custom health checks into a `Healthcheck` module.
 
+### `RailsCache`
+
+This checks that the Rails cache store, such as Memcached, is acessible by
+writing and reading back a cache entry called "healthcheck-cache".
+
+### `Mongoid`
+
+This checks that the app has a connection to its Mongo database via Mongoid.
+
 ### `SidekiqRedis`
 
 This checks that the app has a connection to Redis via Sidekiq.

govuk_app_config.gemspec

@@ -25,7 +25,6 @@ Gem::Specification.new do |spec|
   spec.add_dependency "statsd-ruby", "~> 1.4.0"
   spec.add_dependency "unicorn", ">= 5.4", "< 5.8"
 
-  spec.add_development_dependency "bundler", "~> 1.15"
   spec.add_development_dependency "climate_control"
   spec.add_development_dependency "rack-test", "~> 1.1.0"
   spec.add_development_dependency "rails", "~> 6"

lib/govuk_app_config/govuk_healthcheck.rb

@@ -1,5 +1,7 @@
 require "govuk_app_config/govuk_healthcheck/checkup"
 require "govuk_app_config/govuk_healthcheck/active_record"
+require "govuk_app_config/govuk_healthcheck/mongoid"
+require "govuk_app_config/govuk_healthcheck/rails_cache"
 require "govuk_app_config/govuk_healthcheck/sidekiq_redis"
 require "govuk_app_config/govuk_healthcheck/threshold_check"
 require "govuk_app_config/govuk_healthcheck/sidekiq_queue_check"

lib/govuk_app_config/govuk_healthcheck/mongoid.rb

@@ -0,0 +1,14 @@
+module GovukHealthcheck
+  class Mongoid
+    def name
+      :database_connectivity
+    end
+
+    def status
+      ::Mongoid.default_client.database_names.any?
+      GovukHealthcheck::OK
+    rescue StandardError
+      GovukHealthcheck::CRITICAL
+    end
+  end
+end

lib/govuk_app_config/govuk_healthcheck/rails_cache.rb

@@ -0,0 +1,16 @@
+module GovukHealthcheck
+  class RailsCache
+    def name
+      :rails_cache
+    end
+
+    def status
+      ::Rails.cache.write("healthcheck-cache", true)
+      raise unless ::Rails.cache.read("healthcheck-cache")
+
+      GovukHealthcheck::OK
+    rescue StandardError
+      GovukHealthcheck::CRITICAL
+    end
+  end
+end

lib/govuk_app_config/rails_ext/action_dispatch/debug_exceptions.rb

@@ -27,7 +27,7 @@ def self.should_monkey_patch_log_error?(clazz = ::ActionDispatch::DebugException
 
       def self.monkey_patch_log_error(clazz = ::ActionDispatch::DebugExceptions)
         clazz.class_eval do
-        private
+          private
 
           def log_error(request, wrapper)
             logger = logger(request)

lib/govuk_app_config/version.rb

@@ -1,3 +1,3 @@
 module GovukAppConfig
-  VERSION = "2.3.0".freeze
+  VERSION = "2.4.0".freeze
 end

spec/lib/govuk_healthcheck/mongoid_spec.rb

@@ -0,0 +1,31 @@
+require "spec_helper"
+require "govuk_app_config/govuk_healthcheck"
+require_relative "shared_interface"
+
+RSpec.describe GovukHealthcheck::Mongoid do
+  let(:client) { double(:client, database_names: %w[db]) }
+  let(:mongoid) { double(:mongoid, default_client: client) }
+  before { stub_const("Mongoid", mongoid) }
+
+  describe ".status" do
+    context "when the database is connected" do
+      it_behaves_like "a healthcheck"
+
+      it "returns OK" do
+        expect(subject.status).to eq(GovukHealthcheck::OK)
+      end
+    end
+
+    context "when the database is not connected" do
+      before do
+        allow(client).to receive(:database_names) { raise }
+      end
+
+      it_behaves_like "a healthcheck"
+
+      it "returns CRITICAL" do
+        expect(subject.status).to eq(GovukHealthcheck::CRITICAL)
+      end
+    end
+  end
+end

spec/lib/govuk_healthcheck/rails_cache_spec.rb

@@ -0,0 +1,43 @@
+require "spec_helper"
+require "govuk_app_config/govuk_healthcheck"
+require_relative "shared_interface"
+
+RSpec.describe GovukHealthcheck::RailsCache do
+  let(:cache) { double(:cache, write: true, read: true) }
+  let(:rails) { double(:mongoid, cache: cache) }
+  before { stub_const("Rails", rails) }
+
+  describe ".status" do
+    context "when the cache is available" do
+      it_behaves_like "a healthcheck"
+
+      it "returns OK" do
+        expect(subject.status).to eq(GovukHealthcheck::OK)
+      end
+    end
+
+    context "when the cache is silently unavailable" do
+      before do
+        allow(cache).to receive(:read) { false }
+      end
+
+      it_behaves_like "a healthcheck"
+
+      it "returns CRITICAL" do
+        expect(subject.status).to eq(GovukHealthcheck::CRITICAL)
+      end
+    end
+
+    context "when the cache is loudly unavailable" do
+      before do
+        allow(cache).to receive(:read) { raise }
+      end
+
+      it_behaves_like "a healthcheck"
+
+      it "returns CRITICAL" do
+        expect(subject.status).to eq(GovukHealthcheck::CRITICAL)
+      end
+    end
+  end
+end