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About Red Hat OpenShift support for Windows Containers

Windows Container Support for Red Hat OpenShift enables running Windows compute nodes in an OKD cluster. Running Windows workloads is possible by using the Red Hat Windows Machine Config Operator (WMCO) to install and manage Windows nodes. With Windows nodes available, you can run Windows container workloads in OKD.

The release notes for Red Hat OpenShift for Windows Containers tracks the development of the WMCO, which provides all Windows container workload capabilities in OKD.

Release notes for Red Hat Windows Machine Config Operator 5.0.0

This release of the WMCO provides bug fixes for running Windows compute nodes in an OKD cluster. The components of the WMCO 5.0.0 were released in RHSA-2022:0577.

  • Previously, Windows Containers on Windows Nodes could get assigned an incorrect DNS server IP. This caused DNS resolution to fail. This fix removes the hard-coded cluster DNS information and the DNS server IP is now passed as a command-line argument. As a result, Windows Containers on Windows Nodes get assigned a valid DNS Server IP and DNS resolution works for Windows workloads. (BZ#1994859)

  • Previously, certain commands being run by the WMCO against Windows VMs that used PowerShell as the default SSH shell were not parsed correctly. As a result, these VMs could not be added to a cluster as a node. With this fix the WMCO identifies the default SSH shell of a VM and runs commands accordingly. As a result, VMs with PowerShell as the default SSH shell can now be added to the cluster as a node. (BZ#2000772)

  • Previously, if a Bring-Your-Own-Host (BYOH) VM was specified with a DNS object, the WMCO was not properly associating the VM with its node object. This caused the WMCO to attempt to configure VMs that were already fully configured. With this fix the WMCO correctly resolves the DNS address of the VMs when looking for an associated node. As a result, BYOH VMs are now only configured when needed. (BZ#2005360)

  • Previously, if the windows-exporter metrics endpoint object contained a reference to a deleted machine, the WMCO ignored Deleting phase notification event for those machines. This fix removes the validation of the machine object from event filtering. As a result, the windows-exporter metrics endpoint object is correctly updated even when the machine is still deleting. (BZ#2008601)

  • Previously, if an entity other than the WMCO modified the certificate signing request (CSR) associated with a BYOH node, the WMCO would have a stale reference to the CSR and would be unable to approve it. With this fix, if an update conflict is detected, the WMCO retries the CSR approval until a specified timeout. As a result, the CSR processing completes as expected. (BZ#2032048)

Windows Machine Config Operator prerequisites

The following information details the supported platform 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 platforms based on OKD and WMCO versions

Platform Supported OKD version Supported WMCO version Installer-provisioned infrastructure installation support User-provisioned infrastructure installation support

Amazon Web Services (AWS)

4.6+

WMCO 1.0+

GA

Microsoft Azure

4.6+

WMCO 1.0+

GA

VMware vSphere

4.7+

WMCO 2.0+

GA

Supported platforms for Bring-Your-Own-Host (BYOH) instances based on OKD and WMCO versions

Platform Supported OKD version Supported WMCO version BYOH for installer-provisioned infrastructure installation support BYOH for user-provisioned infrastructure installation support

Amazon Web Services (AWS)

4.8+

WMCO 3.1+

GA

Microsoft Azure

4.8+

WMCO 3.1+

GA

VMware vSphere

4.8+

WMCO 3.1+

GA

Provider agnostic (Platform: none)

4.8+

WMCO 3.1+

GA

Supported Windows Server versions

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

Platform 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 20H2

bare metal

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

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 platform. You must specify the network configuration when you install the cluster. Be aware that OpenShift SDN networking is the default network for OKD clusters. However, OpenShift SDN is not supported by WMCO.

Table 1. Platform networking support
Platform 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

bare metal

Hybrid networking with OVN-Kubernetes

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 20H2

Running Windows container workloads is not supported for clusters in a restricted network or disconnected environment.

Version 5.x of the WMCO is only compatible with OKD 4.10.