changes in Metric Writer to Prometheus.

- start_http_server() call is move to main
- CollectorRegistory variable is removed

src/kpi_value_writer/service/MetricWriterToPrometheus.py

@@ -18,7 +18,7 @@ import ast
 import time
 import threading
 import logging
-from prometheus_client import start_http_server, Gauge, CollectorRegistry
+from prometheus_client import Gauge, CollectorRegistry
 from common.proto.kpi_sample_types_pb2 import KpiSampleType
 
 from common.proto.kpi_value_api_pb2 import KpiValue
@@ -26,7 +26,6 @@ from common.proto.kpi_manager_pb2 import KpiDescriptor
 
 LOGGER         = logging.getLogger(__name__)
 PROM_METRICS   = {}
-PROM_REGISTERY = CollectorRegistry()
 
 class MetricWriterToPrometheus:
     '''
@@ -34,13 +33,7 @@ class MetricWriterToPrometheus:
     cooked KPI value = KpiDescriptor (gRPC message) + KpiValue (gRPC message)
     '''
     def __init__(self):
-        # prometheus server address and configs
-        self.start_prometheus_client()
         pass
-    
-    def start_prometheus_client(self):
-        start_http_server(10808, registry=PROM_REGISTERY)
-        LOGGER.debug("Prometheus client is started on port 10808")
 
     def merge_kpi_descriptor_and_kpi_value(self, kpi_descriptor, kpi_value):
             # Creating a dictionary from the kpi_descriptor's attributes
@@ -71,8 +64,7 @@ class MetricWriterToPrometheus:
                 PROM_METRICS[metric_name] = Gauge ( 
                     metric_name,
                     cooked_kpi['kpi_description'],
-                    metric_tags,
-                    registry=PROM_REGISTERY
+                    metric_tags
                 )
             LOGGER.debug("Metric is created with labels: {:}".format(metric_tags))
             PROM_METRICS[metric_name].labels(

src/kpi_value_writer/service/__main__.py

@@ -13,6 +13,7 @@
 # limitations under the License.
 
 import logging, signal, sys, threading
+from prometheus_client import start_http_server
 from kpi_value_writer.service.KpiValueWriter import KpiValueWriter
 from common.Settings import get_log_level
 
@@ -38,6 +39,8 @@ def main():
     grpc_service = KpiValueWriter()
     grpc_service.start()
 
+    start_http_server(10808)
+    LOGGER.debug("Prometheus client is started on port 10808")
     # Wait for Ctrl+C or termination signal
     while not terminate.wait(timeout=1.0): pass