Now that we had Elasticsearch running in our cluster and knowing that it can handle almost any data type, a logical question could be whether we can use it to store our metrics besides logs. If you explore elastic.co (https://www.elastic.co/), you'll see that metrics are indeed something they advertise. If it could replace Prometheus, it would undoubtedly be beneficial to have a single tool that can handle not only logs but also metrics. On top of that, we could ditch Grafana and keep Kibana as a single UI for both data types.
Nevertheless, I would strongly advise against using Elasticsearch for metrics. It is a general-purpose free-text no-SQL database. That means that it can handle almost any data but, at the same time, it does not excel at any specific format. Prometheus, on the other hand, is designed to store time-series...