bugfix: prometheus scrape jobs populate function called before mongoDB was ready to use

Change-Id: I6bcf6df2c5609394d92a8a7838f53cb06154bf88
Signed-off-by: bravof <fbravo@whitestack.com>
diff --git a/osm_mon/server/service.py b/osm_mon/server/service.py
index 584a42f..d1b408b 100755
--- a/osm_mon/server/service.py
+++ b/osm_mon/server/service.py
@@ -60,7 +60,8 @@
     def populate_prometheus(self):
         # This method can be executed infinite number of times
         # without side-effects.
-        self.common_db.common_db.set_one(
+        log.info("Setting up MON Exporter in prometheus")
+        result = self.common_db.common_db.set_one(
             "prometheus_jobs", {"job_name": "mon_exporter"}, {
                 "job_name": "mon_exporter",
                 "static_configs": [
@@ -74,3 +75,4 @@
             fail_on_empty=False,
             upsert=True
         )
+        log.info("Prometheus Jobs added > {}".format(result))