Prometheus: run queries against Elasticsearch and turn it into metrics and alerts

Long time no read. I'm in the middle of re-implementing our monitoring solution, this time using Prometheus.

We have tons of web- and application-server logs in Elasticsearch and need to query it for http 5xx error rates, application error rates and similar things to get that data into Prometheus for alerting fun.

Enter braedon's prometheus-es-exporter. There's a ready-to-go docker image on docker hub, so all it takes to get things working in kubernetes is this: