Windows Container Support for Red Hat OpenShift provides built-in support for running Microsoft Windows Server containers on OpenShift Container Platform. For those that administer heterogeneous environments with a mix of Linux and Windows workloads, OpenShift Container Platform allows you to deploy Windows workloads running on Windows Server containers while also providing traditional Linux workloads hosted on Red Hat Enterprise Linux CoreOS (RHCOS) or Red Hat Enterprise Linux (RHEL).

Multi-tenancy for clusters that have Windows nodes is not supported. Hostile multi-tenant usage introduces security concerns in all Kubernetes environments. Additional security features like pod security policies, or more fine-grained role-based access control (RBAC) for nodes, make exploits more difficult. However, if you choose to run hostile multi-tenant workloads, a hypervisor is the only security option you should use. The security domain for Kubernetes encompasses the entire cluster, not an individual node. For these types of hostile multi-tenant workloads, you should use physically isolated clusters.

Windows Server Containers provide resource isolation using a shared kernel but are not intended to be used in hostile multitenancy scenarios. Scenarios that involve hostile multitenancy should use Hyper-V Isolated Containers to strongly isolate tenants.

Windows Machine Config Operator prerequisites

The following information details the supported cloud provider versions, Windows Server versions, and networking configurations for the Windows Machine Config Operator. See the vSphere documentation for any information that is relevant to only that platform.

Supported cloud providers based on OpenShift Container Platform and WMCO versions

Cloud provider Supported OpenShift Container Platform version Supported WMCO version

Amazon Web Services (AWS)

4.6+

WMCO 1.0+

Microsoft Azure

4.6+

WMCO 1.0+

VMware vSphere

4.7+

WMCO 2.0+

Supported Windows Server versions

The following table lists the supported Windows Server version based on the applicable cloud provider. Any unlisted Windows Server version is not supported and will cause errors. To prevent these errors, only use the appropriate version according to the cloud provider in use.

Cloud provider Supported Windows Server version

Amazon Web Services (AWS)

Windows Server Long-Term Servicing Channel (LTSC): Windows Server 2019

Microsoft Azure

Windows Server Long-Term Servicing Channel (LTSC): Windows Server 2019

VMware vSphere

Windows Server Semi-Annual Channel (SAC): Windows Server 2004 and 20H2

Supported networking

Hybrid networking with OVN-Kubernetes is the only supported networking configuration. See the additional resources below for more information on this functionality. The following tables outline the type of networking configuration and Windows Server versions to use based on your cloud provider. You must specify the network configuration when you install the cluster. Be aware that OpenShift SDN networking is the default network for OpenShift Container Platform clusters. However, OpenShift SDN is not supported by WMCO.

Table 1. Cloud provider networking support
Cloud provider Supported networking

Amazon Web Services (AWS)

Hybrid networking with OVN-Kubernetes

Microsoft Azure

Hybrid networking with OVN-Kubernetes

VMware vSphere

Hybrid networking with OVN-Kubernetes with a custom VXLAN port

Table 2. Hybrid OVN-Kubernetes Windows Server support
Hybrid networking with OVN-Kubernetes Supported Windows Server version

Default VXLAN port

Windows Server Long-Term Servicing Channel (LTSC): Windows Server 2019

Custom VXLAN port

Windows Server Semi-Annual Channel (SAC): Windows Server 2004 and 20H2

Supported installation method

The installer-provisioned infrastructure installation method is the only supported installation method. This is consistent across all supported cloud providers. User-provisioned infrastructure installation method is not supported.

Windows workload management

To run Windows workloads in your cluster, you must first install the Windows Machine Config Operator (WMCO). The WMCO is a Linux-based Operator that runs on Linux-based control plane and compute nodes. The WMCO orchestrates the process of deploying and managing Windows workloads on a cluster.