Make RedisConnection Check Require Redis Instance Parameter

CHANGELOG.md

@@ -5,6 +5,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 
 ## [Unreleased]
 
+### Changed
+
+- **Breaking**: The Redis check now requires being configured with an instance of the Redis client, via the named `instance` parameter
+
 ### Added
 
 - The `static` check, which uses the provided check parameters to return the same result every time.

README.md

@@ -157,7 +157,7 @@ Requires a configured ActiveRecord connection, and that ActiveRecord migrations
 
 #### `redis`
 
-Requires a configured global Redis client. Does not support configuration. Indicates whether the global client is currently connected to the Redis database. On success, returns something in the following format:
+Requires the Redis gem. Requires configuration, an instance of a Redis client. Indicates whether the Redis client passed in is currently connected to the Redis database. On success, returns something in the following format:
 
 ```json
 {

lib/rack/ecg/check/redis_connection.rb

@@ -3,17 +3,26 @@ module Rack
   class ECG
     module Check
       # @!method initialize
-      #   Checks whether the global Redis client is currently connected to the
-      #   database.
+      #   Checks whether the given Redis client is currently connected to the
+      #   database as identified by the ++instance++ option.
       #
-      #   Does not take any options.
+      # @option parameters instance [Redis] The Redis client
       class RedisConnection
+        attr_reader :redis_instance
+
+        def initialize(parameters = {})
+          @redis_instance = parameters[:instance]
+        end
+
         def result
           value = ""
           status = Status::OK
           begin
-            if defined?(::Redis)
-              value = ::Redis.current.connected?
+            if redis_instance.nil?
+              status = Status::ERROR
+              value = "Redis instance parameters not found"
+            elsif defined?(::Redis)
+              value = redis_instance.connected?
               status = value ? Status::OK : Status::ERROR
             else
               status = Status::ERROR

spec/rack_middleware_spec.rb

@@ -195,24 +195,51 @@ def self.connection
 
     context "redis" do
       let(:options) do
-        { checks: [:redis] }
+        { checks: [[:redis, { instance: instance }]] }
       end
+      let(:instance) { instance_double("Redis", connected?: connected) }
+      let(:connected) { true }
+
+      before do
+        # make sure Redis is defined
+        class Redis
+          def connected?
+          end
+        end unless defined?(Redis)
+      end
+
       context "when available" do
-        let(:instance) { double("current") }
-        let(:connected) { true }
         it "is reported" do
-          class Redis
-            def self.current
-            end
-          end
-          expect(Redis).to(receive(:current).and_return(instance))
           expect(instance).to(receive(:connected?).and_return(connected))
           get "/_ecg"
           expect(json_body["redis"]["status"]).to(eq("ok"))
           expect(json_body["redis"]["value"]).to(eq(connected.to_s))
         end
       end
 
+      context "the instance is not connected" do
+        let(:connected) { false }
+
+        it "is reported" do
+          expect(instance).to(receive(:connected?).and_return(connected))
+          get "/_ecg"
+          expect(json_body["redis"]["status"]).to(eq("error"))
+          expect(json_body["redis"]["value"]).to(eq(connected.to_s))
+        end
+      end
+
+      context "without instance parameters" do
+        let(:options) do
+          { checks: [:redis] }
+        end
+
+        it "is reported" do
+          get "/_ecg"
+          expect(json_body["redis"]["status"]).to(eq("error"))
+          expect(json_body["redis"]["value"]).to(eq("Redis instance parameters not found"))
+        end
+      end
+
       context "when not available" do
         it "is reported" do
           Object.send(:remove_const, :Redis) if defined?(Redis)