Prometheus – is a monitoring tool in cloud native environments like Kubernetes.
Prometheus mainly stores time series of numerical values. Each of these time series is identified by a combination of text based labels, which makes it filter through its query language called PromQL.
Prometheus can automatically discover metrics and start to scrape them literally from the first minute. This autodiscovery is not only limited to Kubernetes, but to platform specific resources like AWS, Azure, GCE, and others.