Extract PrometheusMetrics to its own file

bin/gitlab-mon-ssh

@@ -24,28 +24,6 @@ class GitRunner
   end
 end
 
-class PrometheusMetrics
-  def initialize
-    @metrics = {}
-  end
-
-  def add(name, value, **labels)
-    @metrics[name] = { value: value, labels: labels, timestamp: (Time.now.to_f * 1000).to_i}
-  end
-
-  def to_s
-    buffer = StringIO.new
-    @metrics.each { |name, metrics|
-      buffer.write("#{name}")
-      labels = (metrics[:labels] || {}).map { |label, value| "#{label}=\"#{value}\"" }.join(",")
-      buffer.write("{#{labels}}") unless labels.empty?
-      buffer.write(" #{metrics[:value]} #{metrics[:timestamp]}\n")
-    }
-    buffer.rewind
-    buffer.read
-  end
-end
-
 def main
   runner = GitRunner.new(File.expand_path("~/dev/emptyness"))
   metrics = PrometheusMetrics.new

lib/gitlab_monitor.rb

 module GitLab
   module Monitor
     autoload :TimeTracker, "gitlab_monitor/util"
+    autoload :PrometheusMetrics,  "gitlab_monitor/prometheus"
   end
 end

lib/gitlab_monitor/prometheus.rb

+module GitLab
+  module Monitor
+    class PrometheusMetrics
+      def initialize
+        @metrics = {}
+      end
+
+      def add(name, value, **labels)
+        @metrics[name] = { value: value, labels: labels, timestamp: (Time.now.to_f * 1000).to_i}
+        self
+      end
+
+      def to_s
+        buffer = StringIO.new
+        @metrics.each { |name, metrics|
+          buffer.write("#{name}")
+          labels = (metrics[:labels] || {}).map { |label, value| "#{label}=\"#{value}\"" }.join(",")
+          buffer.write("{#{labels}}") unless labels.empty?
+          buffer.write(" #{metrics[:value]} #{metrics[:timestamp]}\n")
+        }
+        buffer.rewind
+        buffer.read
+      end
+    end
+  end
+end

spec/util_spec.rb

@@ -5,3 +5,18 @@ describe GitLab::Monitor::TimeTracker do
     expect(subject.track { sleep 0.1 }).to satisfy {|v| v >= 0.1}
   end
 end
+
+describe GitLab::Monitor::PrometheusMetrics do
+  it "supports simple metrics" do
+    expect(subject.add("mymetric", 1.1).to_s).to match(/mymetric 1.1 \d*$/)
+  end
+
+  it "supports metrics with one label" do
+    expect(subject.add("mymetric", 1.2, mylabel: "x").to_s).to match(/mymetric{mylabel="x"} 1.2 \d*$/)
+  end
+
+  it "supports metrics with many labels" do
+    expect(subject.add("mymetric", 1.3, mylabel: "x", myotherlabel: "y").to_s).to match(
+      /mymetric{mylabel="x",myotherlabel="y"} 1.3 \d*$/)
+  end
+end