include prometheus metrics, refs #200

owrx/controllers/metrics.py

@@ -1,9 +1,30 @@
 from . import Controller
-from owrx.metrics import Metrics
+from owrx.metrics import CounterMetric, DirectMetric, Metrics
 import json
 
 
 class MetricsController(Controller):
     def indexAction(self):
-        data = json.dumps(Metrics.getSharedInstance().getMetrics())
+        data = json.dumps(Metrics.getSharedInstance().getHierarchicalMetrics())
         self.send_response(data, content_type="application/json")
+
+    def prometheusAction(self):
+        metrics = Metrics.getSharedInstance().getFlatMetrics()
+
+        def prometheusFormat(key, metric):
+            value = metric.getValue()
+            if isinstance(metric, CounterMetric):
+                key += "_total"
+                value = value["count"]
+            elif isinstance(metric, DirectMetric):
+                pass
+            else:
+                raise ValueError("Unexpected metric type for metric {}".format(repr(metric)))
+
+            return "{key} {value}".format(key=key.replace(".", "_"), value=value)
+
+        data = ["# https://prometheus.io/docs/instrumenting/exposition_formats/"] + [
+            prometheusFormat(k, v) for k, v in metrics.items()
+        ]
+
+        self.send_response("\n".join(data), content_type="text/plain; version=0.0.4")