Kubernetes with ETCD needs ETCD-Cluster installation


I have an Kubernetes-Cluster within Rancher by catalag installation. Therefore there is an “rancher/etcd:v2.3.7-13” container on every host.

When I install for example a postgres-cluster by Helm there is an ETCD cluster mandatory. Do I need this extra installation (for example by CoreOs) or can I use the ETCD installation done by Rancher in Kubernetes? When so, what is the endpoint address of this ETCD cluster.