Prometheus is a general purpose monitoring tool that can also collect and analyze metrics from applications running on a Kubernetes cluster.
Prometheus is available from https://prometheus.io/
The Prometheus Operator makes the Prometheus configuration Kubernetes native and manages Prometheus instances on top of Kubernetes. For information about the Prometheus Operator project, see https://github.com/coreos/prometheus-operator.
kube-prometheus is a repository in the Prometheus Operator project. It includes manifests, Grafana dashboards, and Prometheus rules, documentation, and scripts, to provide single-command deployments of end-to-end Kubernetes cluster monitoring with Prometheus. For information about kube-prometheus, see https://github.com/coreos/prometheus-operator/tree/master/contrib/kube-prometheus.
To deploy Prometheus instances that are managed by the Prometheus Operator, use the assets in kube-prometheus repository.