Large changes to the underlying architecture and installation process are applied in OKD v4, and many features from OKD v3 are now deprecated.

Features deprecated in OKD v4

Table 1. Features Deprecated in Latest
Feature Justification

Hawkular

Replaced by cluster monitoring.

Cassandra

Replaced by cluster monitoring.

Heapster

Replaced by Prometheus adapter.

Atomic Host

Replaced by Red Hat Enterprise Linux CoreOS.

System containers

Replaced by Red Hat Enterprise Linux CoreOS.

projectatomic/docker-1.13 additional search registries

CRI-O is the default container runtime for OpenShift v4 on RHCOS and Red Hat Enterprise Linux.

oc adm diagnostics

Operator-based diagnostics.

oc adm registry

Replaced by the Image Registry Operator.

Custom strategy builds using Docker

If you want to continue using custom builds, you should replace your Docker invocations with Podman or Buildah. The custom build strategy will not be removed, but the functionality changed significantly in OpenShift v4.

Cockpit

Improved OpenShift v4 web console.

Stand-alone registry installations

Quay is Red Hat’s enterprise container image registry.

DNSmasq

CoreDNS is the default.

External etcd nodes

etcd is always on the cluster in OpenShift v4.

CloudForms OpenShift Provider and Podified CloudForms

Replaced by built-in management tooling.

Volume Provisioning via installer

Replaced by dynamic volumes or, if NFS is required, NFS provisioner.

Blue-green installation method

Ease of upgrade is a core value of OpenShift v4.

OpenShift Service Broker and Service Catalog

The Service Catalog and the OpenShift service brokers are being replaced over the course of several future OpenShift v4 releases. Reference the Operator Framework and Operator Lifecycle Manager (OLM) to continue providing your applications to OpenShift v4 clusters. These new technologies provide many benefits around complete management of the lifecycle of your application.

oc adm ca

Certificates are managed by Operators internally.

oc adm create-api-client-config

Functions are managed by Operators internally.

oc adm create-bootstrap-policy-file

oc adm policy reconcile-sccs

Functions are managed by openshift-apiserver internally.

Web console

The web console from OpenShift v3 has been replaced by a new web console in OpenShift v4.