feat: add missing prometheus metrics (#342)

Add missing prometheus metrics for monitoring

Signed-off-by: jcriadomarco <[email protected]>

Signed-off-by: jcriadomarco <[email protected]>

Author: javiercri

config-reloader/templates/prometheus.conf

@@ -12,4 +12,24 @@
   @type prometheus_output_monitor
   @id in_prometheus_output_monitor
 </source>
+
+<source>
+  @type prometheus_tail_monitor
+</source>
+
+<filter **>
+  @type prometheus
+  @id filter_prometheus
+  @log_level warn
+
+  <metric>
+    name fluentd_input_status_num_records_total
+    type counter
+    desc The total number of incoming records
+    <labels>
+      tag ${tag_parts[0]}
+      hostname ${hostname}
+    </labels>
+  </metric>
+</filter>
 {{- end -}}