Combine multiple probers into one

Gemfile.lock

 PATH
   remote: .
   specs:
-    gitlab-monitor (0.0.5)
+    gitlab-monitor (0.0.6)
       pg (~> 0.18.4)
       sinatra (~> 1.4.7)
 

config/gitlab-monitor.yml.example

@@ -3,12 +3,14 @@ server:
   listen_port: 4567
 
 probes:
-  dead_tuples_count:
-    class_name: Database::DeadTuplesProber
-    methods:
-      - probe_db
-    opts:
-      connection_string: dbname=gitlabhq_development user=postgres
+  database:
+    multiple: true
+    dead_tuples_count:
+      class_name: Database::DeadTuplesProber
+      methods:
+        - probe_db
+      opts:
+        connection_string: dbname=gitlabhq_development user=postgres
   git:
     methods:
       - probe_pull

lib/gitlab_monitor.rb

@@ -11,5 +11,6 @@ module GitLab
     autoload :Database,          "gitlab_monitor/database"
     autoload :ProcessProber,     "gitlab_monitor/process"
     autoload :WebExporter,       "gitlab_monitor/web_exporter"
+    autoload :Prober,            "gitlab_monitor/prober"
   end
 end

lib/gitlab_monitor/prober.rb

+module GitLab
+  module Monitor
+    # A class to combine multiple probers into one
+    class Prober
+      def initialize(prober_opts, metrics: PrometheusMetrics.new)
+        @prober_opts = prober_opts
+        @metrics     = metrics
+
+        resolve_prober_classes
+      end
+
+      def probe_all
+        @prober_opts.each do |_probe_name, params|
+          Utils.wrap_in_array(params[:opts]).each do |opts|
+            prober = params[:class].new(opts, metrics: @metrics)
+            params[:methods].each do |meth|
+              prober.send(meth)
+            end
+          end
+        end
+      end
+
+      def write_to(target)
+        target.write(@metrics.to_s)
+      end
+
+      private
+
+      def resolve_prober_classes
+        @prober_opts.each do |probe_name, params|
+          prober_class_name = params[:class_name] || Utils.camel_case_string("#{probe_name}_prober")
+
+          klass = prober_class_name.split("::").reduce(GitLab::Monitor) { |a, e| a.const_get(e) }
+
+          params[:class] = klass
+        end
+      end
+    end
+  end
+end

lib/gitlab_monitor/version.rb

 module GitLab
   module Monitor
-    VERSION = "0.0.5".freeze
+    VERSION = "0.0.6".freeze
   end
 end

lib/gitlab_monitor/web_exporter.rb

@@ -17,30 +17,25 @@ module GitLab
           set(:port, config.fetch(:listen_port, 4567))
         end
 
-        def setup_probes(config) # rubocop:disable Metrics/AbcSize
+        def setup_probes(config)
           (config || {}).each do |probe_name, params|
-            prober_class_name = params.delete(:class_name) || Utils.camel_case_string("#{probe_name}_prober")
-            prober_class = resolve_prober_class(prober_class_name)
+            opts =
+              if params.delete(:multiple)
+                params
+              else
+                { probe_name => params }
+              end
 
             get "/#{probe_name}" do
-              Utils.wrap_in_array(params[:opts]).each do |opts|
-                prober = prober_class.new(opts, metrics: PrometheusMetrics.new(include_timestamp: false))
-                params[:methods].each do |meth|
-                  prober.send(meth)
-                end
-                prober.write_to(response)
-              end
+              prober = Prober.new(opts, metrics: PrometheusMetrics.new(include_timestamp: false))
+
+              prober.probe_all
+              prober.write_to(response)
 
               response
             end
           end
         end
-
-        def resolve_prober_class(prober_class_name)
-          prober_class_name.split("::").reduce(GitLab::Monitor) do |ancestor, const_name|
-            ancestor.const_get(const_name)
-          end
-        end
       end
     end
   end