feat: add prometheus metrics to worker

app/util/has_prometheus_metrics.rb

@@ -7,6 +7,11 @@ module HasPrometheusMetrics
     registry.register(counter)
   end
 
+  def register_prometheus_histogram(name, **kwargs)
+    histogram = Prometheus::Client::Histogram.new(name, **kwargs)
+    registry.register(histogram)
+  end
+
   def increment_prometheus_counter(name, labels: {})
     counter = registry.get(name)
     return if counter.nil?
@@ -14,6 +19,13 @@ module HasPrometheusMetrics
     counter.increment(labels: labels)
   end
 
+  def observe_prometheus_histogram(name, time, labels: {})
+    histogram = registry.get(name)
+    return if histogram.nil?
+
+    histogram.observe(time, labels: labels)
+  end
+
   private
 
   def registry