Added sample configs for prometheus.

README.md

@@ -37,4 +37,59 @@ curl -XPOST -H 'Content-Type: application/json;' leader.mesos:8080/v2/apps -d '{
   },
   "healthChecks": [{"protocol": "HTTP", "path": "/metrics"}]
 }'
-`
+```
+
+## Scrape config on prometheus
+
+A sample prometheus target yaml example if you already have have mesos-dns:
+
+```yaml
+  - job_name: 'marathon-app'
+    dns_sd_configs:
+      - names: ['_marathon-app-exporter-prom._tcp.marathon.mesos']
+```
+
+## Alerts on prometheus
+
+And some sample alert rules for firing alerts from Prometheus:
+
+```
+ALERT MarathonAppIsRunningOnReducedCapacity
+  IF sum(marathon_apps_instances{job="marathon-app"} - marathon_apps_tasksRunning{job="marathon-app"}) by (id) > 0
+  FOR 30m
+  SUMMARY "Marathon app hass less instances that it should have."
+  DESCRIPTION "Check why this app hass less instancess that it should heve. Possibly a cancelled deployment or resource starvation issue."
+
+ALERT MarathonAppIsNotHealthy
+  IF sum(
+       marathon_apps_tasksHealthy{job="marathon-app"} > 0 and
+       marathon_apps_instances{job="marathon-app"} > marathon_apps_tasksRunning{job="marathon-app"}
+     ) by (id)
+  FOR 10m
+  SUMMARY "Marathon app does not have enough healthy instances."
+  DESCRIPTION "Check if there is resource starvation or constraints forcing app to be installed a a specific node with problems."
+
+ALERT MarathonAppCantGetSuitableOffers
+  IF sum(marathon_queue_delay_overdue{job="marathon-app"} == 1) by (id)
+  FOR 15m
+  SUMMARY "No suitable offers for this app."
+  DESCRIPTION "This app can't be scheduled to any suitable node, check constraints or any resource starvation."
+
+ALERT MarathonAppDeploymentDelayed
+  IF sum(
+       marathon_queue_delay_timeLeftSeconds{job="marathon-app"} > 0 and
+       marathon_queue_delay_overdue{job="marathon-app"} == 0
+     ) by (id)
+  FOR 30m
+  SUMMARY "Delayed deployment."
+  DESCRIPTION "Delayed deployment."
+
+ALERT MarathonAppHasTasksWithOldConfig
+  IF sum(
+       marathon_apps_taskStats_totalSummary_stats_counts_running{job="marathon-app"} -
+       marathon_apps_taskStats_withLatestConfig_stats_counts_running{job="marathon-app"} > 0
+     ) by (id)
+  FOR 30m
+  SUMMARY "App with old instance configs."
+  DESCRIPTION "There could be some deployments cancelled"
+```