Add Y Label field to yml and responses

Author: pawelchcki

config/additional_metrics.yml

@@ -2,6 +2,7 @@
   priority: 1
   metrics:
   - title: "Memory usage"
+    y_label: "Values"
     detect: container_memory_usage_bytes
     weight: 1
     queries:

lib/gitlab/prometheus/metric.rb

@@ -1,20 +1,21 @@
 module Gitlab::Prometheus
   class Metric
-    attr_reader :group, :title, :detect, :weight, :queries
+    attr_reader :group, :title, :detect, :weight, :y_label, :queries
 
-    def initialize(group, title, detect, weight, queries = [])
+    def initialize(group, title, detect, weight, y_label, queries = [])
       @group = group
       @title = title
       @detect = detect
       @weight = weight
+      @y_label = y_label || 'Values'
       @queries = queries
     end
 
     def self.metric_from_entry(group, entry)
       missing_fields = [:title, :detect, :weight, :queries].select { |key| !entry.has_key?(key) }
       raise ParsingError.new("entry missing required fields #{missing_fields}") unless missing_fields.empty?
 
-      Metric.new(group, entry[:title], entry[:detect], entry[:weight], entry[:queries])
+      Metric.new(group, entry[:title], entry[:detect], entry[:weight], entry[:y_label],entry[:queries])
     end
 
     def self.metrics_from_list(group, list)

lib/gitlab/prometheus/metrics_sources.rb

@@ -22,6 +22,7 @@ def query_metrics(query_context)
           {
             title: metric.title,
             weight: metric.weight,
+            y_label: metric.y_label,
             queries: metric.queries.map(&query_processor)
           }
         end