Add mon-exporter as scrape target in Prometheus

The Prometheus sidecar is expected to generate the scrape targets from
the config map and from the prometheus_jobs in MongoDB. MON is adding
mon-exporter as prometheus_job in MongoDB. There are race conditions in
the start of MON and Prometheus that prevent the sidecar to be aware
of the mon-exporter being added to prometheus_jobs collection in
MongoDB.

This change adds mon-exporter to the default scrape-targets and reconciles
the jobs in Mongo and the jobs in the configmap, prevailing the job in the
configmap if duplicated.

Change-Id: Ib6f1cb89723d7b4942eeb77fd0ea46a0d3493d58
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>
diff --git a/installers/docker/osm_pods/prometheus.yaml b/installers/docker/osm_pods/prometheus.yaml
index 2610710..241ed72 100644
--- a/installers/docker/osm_pods/prometheus.yaml
+++ b/installers/docker/osm_pods/prometheus.yaml
@@ -73,8 +73,10 @@
 
     # A scrape configuration containing exactly one endpoint to scrape:
     # Here it's Prometheus itself.
-    scrape_configs: []
-    # scrape_configs:
+    scrape_configs:
+      - job_name: 'mon_exporter'
+        static_configs:
+        - targets: ['mon:8000']
       # Add here other external targets, e.g. a pushgateway
       # - job_name: 'pushgateway'
       #   static_configs: