fix(prometheus): strip period from prometheus metrics names DEVX-637 (#…

…677)

* Make sure metrics names based on span name don't include disallowed chars for prometheus

see: https://reddit.slack.com/archives/CCM109VKM/p1654127902504289
see: https://github.com/prometheus/client_python/blob/748ffb00600dc25fbd22d37d549578e8e370d996/prometheus_client/metrics_core.py#L10

* remove spacing (linting)

baseplate/lib/prometheus_metrics.py

@@ -1,4 +1,5 @@
 import logging
+import re
 
 from typing import Any
 from typing import Dict
@@ -446,6 +447,11 @@ def get_active_requests_metric(cls) -> Gauge:
 
 
 def get_metrics_for_prefix(prefix: str) -> PrometheusGenericSpanMetrics:
+    # make sure metric names don't include disallowed chars
+    # https://github.com/prometheus/client_python/blob/748ffb00600dc25fbd22d37d549578e8e370d996/prometheus_client/metrics_core.py#L10
+    prefix = prefix.replace(".", "_")
+    prefix = re.sub("[^0-9a-zA-Z_:]+", "", prefix)
+
     if prefix not in generic_metrics:
         # local labels and metrics
         labels = [