fix ipv6 support for prometheus

prometheus.py

@@ -6,6 +6,7 @@ import logging
 from time import time
 from collections import defaultdict
 from http.server import BaseHTTPRequestHandler, HTTPServer
+from socket import AF_INET6
 from urllib.parse import parse_qs, urlparse
 from prometheus_client import (
     CollectorRegistry, Gauge, generate_latest, CONTENT_TYPE_LATEST
@@ -96,6 +97,8 @@ class Prometheus():
         return registry
 
     def listen(self, addr=("127.0.0.1", 8080)):
+        if "::" in addr[0]:
+            HTTPServer.address_family = AF_INET6
         server = HTTPServer(addr, DynamicMetricsHandler.factory(self.handler))
         server.serve_forever()