Update example-prometheus.yml

Signed-off-by: pincher95 <yuri.tsuprun@logz.io>

Author: pincher95

examples/example-prometheus.yml

@@ -1,19 +1,33 @@
 scrape_configs:
   - job_name: es-multi
     metrics_path: /probe
+    # Default parameters for all scrapes in this job.
+    # Can be overridden by labels on a per-target basis.
     params:
-      auth_module: [prod_key] # default for all targets in this block
+      auth_module: [prod_key]
     static_configs:
+      # This is a target group. All targets here will use the default 'prod_key' auth_module.
       - targets:
-          - https://es-prod:9200 # uses prod_key
+          - https://es-prod-1:9200
+          - https://es-prod-2:9200
+      # This is another target group.
       - targets:
-          - https://es-stage:9200 # will override auth_module below
+          - https://es-stage:9200
+        # The __param_ prefix on a label causes it to be added as a URL parameter.
+        # This will override the default auth_module for this target.
         labels:
           __param_auth_module: staging_basic
     relabel_configs:
+      # The following relabeling rules are applied to every target.
+
+      # 1. The special label __address__ (the target address) is saved as the 'target' URL parameter.
       - source_labels: [__address__]
         target_label: __param_target
+
+      # 2. The 'target' parameter is used as the 'instance' label for the scraped metrics.
       - source_labels: [__param_target]
         target_label: instance
+
+      # 3. The scrape address is rewritten to point to the exporter.
       - target_label: __address__
         replacement: exporter:9114 # host:port of the single exporter