Allow enabling/disabling _created metrics from code (#973)

Signed-off-by: Chris Marchbanks <[email protected]>

prometheus_client/__init__.py

@@ -11,7 +11,10 @@
     write_to_textfile,
 )
 from .gc_collector import GC_COLLECTOR, GCCollector
-from .metrics import Counter, Enum, Gauge, Histogram, Info, Summary
+from .metrics import (
+    Counter, disable_created_metrics, enable_created_metrics, Enum, Gauge,
+    Histogram, Info, Summary,
+)
 from .metrics_core import Metric
 from .platform_collector import PLATFORM_COLLECTOR, PlatformCollector
 from .process_collector import PROCESS_COLLECTOR, ProcessCollector
@@ -27,6 +30,8 @@
     'Histogram',
     'Info',
     'Enum',
+    'enable_created_metrics',
+    'disable_created_metrics',
     'CONTENT_TYPE_LATEST',
     'generate_latest',
     'MetricsHandler',

prometheus_client/metrics.py

@@ -70,6 +70,18 @@ def _get_use_created() -> bool:
 _use_created = _get_use_created()
 
 
+def disable_created_metrics():
+    """Disable exporting _created metrics on counters, histograms, and summaries."""
+    global _use_created
+    _use_created = False
+
+
+def enable_created_metrics():
+    """Enable exporting _created metrics on counters, histograms, and summaries."""
+    global _use_created
+    _use_created = True
+
+
 class MetricWrapperBase(Collector):
     _type: Optional[str] = None
     _reserved_labelnames: Sequence[str] = ()