Chapter 2. Red Hat OpenShift support for Windows Containers release notes
2.1. About Red Hat OpenShift support for Windows Containers
Windows Container Support for Red Hat OpenShift enables running Windows compute nodes in an OpenShift Container Platform 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 OpenShift Container Platform.
These release notes track the development of the WMCO, which provides all Windows container workload capabilities in OpenShift Container Platform.
2.2. Getting support
Windows Container Support for Red Hat OpenShift is provided and available as an optional, installable component. Windows Container Support for Red Hat OpenShift is not part of the OpenShift Container Platform subscription. It requires an additional Red Hat subscription and is supported according to the Scope of coverage and Service level agreements.
You must have this separate subscription to receive support for Windows Container Support for Red Hat OpenShift. Without this additional Red Hat subscription, deploying Windows container workloads in production clusters is not supported. You can request support through the Red Hat Customer Portal.
For more information, see the Red Hat OpenShift Container Platform Life Cycle Policy document for Red Hat OpenShift support for Windows Containers.
If you do not have this additional Red Hat subscription, you can use the Community Windows Machine Config Operator, a distribution that lacks official support.
2.3. Release notes for Red Hat Windows Machine Config Operator 8.1.2
This release of the WMCO provides new features and bug fixes for running Windows compute nodes in an OpenShift Container Platform cluster. The components of WMCO 8.1.2 were released in RHSA-2024:1477.
2.3.1. Bug fixes
- Previously, because of bad logic in the networking configuration script, the WICD was incorrectly reading carriage returns in the CNI configuration file as changes, and identified the file as modified. This caused the CNI configuration to be unnecessarily reloaded, potentially resulting in container restarts and brief network outages. With this fix, the WICD now reloads the CNI configuration only when the CNI configuration is actually modified. (OCPBUGS-27046)
- Previously, because of a lack of synchronization between Windows machine set nodes and BYOH instances, during an update the machine set nodes and the BYOH instances could update simultaneously. This could impact running workloads. This fix introduces a locking mechanism so that machine set nodes and BYOH instances update individually. (OCPBUGS-23016)
2.4. Release notes for Red Hat Windows Machine Config Operator 8.1.1
This release of the WMCO provides new features and bug fixes for running Windows compute nodes in an OpenShift Container Platform cluster. The components of WMCO 8.1.1 were released in RHBA-2023:7709.
2.4.1. Bug fixes
- Previously, the WMCO did not properly wait for Windows virtual machines (VMs) to finish rebooting. This led to occasional timing issues where the WMCO would attempt to interact with a node that was in the middle of a reboot, causing WMCO to log an error and restart node configuration. Now, the WMCO waits for the instance to completely reboot. (OCPBUGS-20259)
- Previously, the WMCO configuration was missing the DeleteEmptyDirData: true field, which is required for draining nodes that have emptyDir volumes attached. As a consequence, customers that had nodes with emptyDir volumes would see the following error in the logs: cannot delete Pods with local storage. With this fix, the DeleteEmptyDirData: true field was added to the node drain helper struct in the WMCO. As a result, customers are able to drain nodes with emptyDir volumes attached. (OCPBUGS-22748)
2.5. Release notes for Red Hat Windows Machine Config Operator 8.0.1
This release of the WMCO provides new features and bug fixes for running Windows compute nodes in an OpenShift Container Platform cluster. The components of WMCO 8.0.1 were released in RHBA-2023:3738.
2.5.1. New features and improvements
2.5.1.1. Windows Server 2022 support
With this release, Windows Server 2022 now supports Amazon Web Services (AWS).
2.5.2. Bug fixes
-
Previously, on an Azure Windows Server 2019 platform that does not have Azure container services installed, WMCO would fail to deploy Windows instances and would display the Install-WindowsFeature : Win32 internal error "Access is denied" 0x5 occurred while reading the console output buffer error message. The failure occurred because the Microsoft
Install-WindowsFeaturecmdlet displays a progress bar that cannot be sent over an SSH connection. This fix hides the progress bar. As a result, Windows instances can be deployed as nodes. (OCPBUGS-14181)
2.6. Release notes for Red Hat Windows Machine Config Operator 8.0.0
This release of the WMCO provides new features and bug fixes for running Windows compute nodes in an OpenShift Container Platform cluster. The components of the WMCO 8.0.0 were released in RHBA-2023:3738.
Due to a known issue, WMCO 8.0.0 is not available to download and use. The issue will be addressed in WMCO 8.0.1, which is planned for release. If you upgrade your cluster from OpenShift Container Platform 4.12 to OpenShift Container Platform 4.13, you can continue to use WMCO 7.0.x. However, you will not be able to use the new WMCO 8.0.0 functionality, as described in this section.
2.6.1. New features and improvements
2.6.1.1. Support for the pod os parameter
You can now use the spec.os.name.windows parameter in your workload pods to authoritatively identify the pod operating system for validation and to enforce Windows-specific pod security context constraints (SCCs). It is recommended that you configure this parameter in your workload pods.
For more information, see Sample Windows container workload deployment.
2.6.1.2. WICD logs are added to must-gather
The must-gather tool now collects the service logs generated by the Windows Instance Config Daemon (WICD) from Windows nodes.
2.6.2. Bug fixes
-
Previously, the test to determine if the Windows Defender antivirus service is running was incorrectly checking for any process whose name started with
Windows Defender, regardless of state. This resulted in an error when the WMCO created firewall exclusions for containerd on instances withoutWindows Defenderinstalled. This fix now checks for the presence of the specific running process associated with the Windows Defender antivirus service. As a result, the WMCO can properly configure Windows instances as nodes regardless of whether Windows Defender is installed. (OCPBUGS-1513) - Previously, in-tree storage was not working for Windows nodes on VMware vSphere. With this fix, Red Hat OpenShift support for Windows Containers properly supports in-tree storage for all cloud providers. (WINC-1014)
2.7. 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.
The following table lists the Windows Server versions that are supported by WMCO 8.1.1, based on the applicable platform. Windows Server versions not listed are not supported, and attempting to use them will cause errors. To prevent these errors, use only an appropriate version for your platform.
2.7.1. WMCO 8.1.x supported platforms and Windows Server versions
The following table lists the Windows Server versions that are supported by WMCO 8.1.x, based on the applicable platform. Windows Server versions not listed are not supported and attempting to use them will cause errors. To prevent these errors, use only an appropriate version for your platform.
| Platform | Supported Windows Server version |
|---|---|
| Amazon Web Services (AWS) |
|
| Microsoft Azure |
|
| VMware vSphere | Windows Server 2022, OS Build 20348.681 or later |
| Google Cloud Platform (GCP) | Windows Server 2022, OS Build 20348.681 or later |
| Bare metal or provider agnostic |
|
2.7.2. WMCO 8.0.1 supported platforms and Windows Server versions
The following table lists the Windows Server versions that are supported by WMCO 8.0.1, based on the applicable platform. Windows Server versions not listed are not supported, and attempting to use them will cause errors. To prevent these errors, use only an appropriate version for your platform.
| Platform | Supported Windows Server version |
|---|---|
| Amazon Web Services (AWS) |
|
| Microsoft Azure |
|
| VMware vSphere | Windows Server 2022, OS Build 20348.681 or later |
| Google Cloud Platform (GCP) | Windows Server 2022, OS Build 20348.681 or later |
| Bare metal or provider agnostic |
|
2.7.3. WMCO 8.0.0 supported platforms and Windows Server versions
The following table lists the Windows Server versions that are supported by WMCO 8.0.0, based on the applicable platform. Windows Server versions not listed are not supported, and attempting to use them will cause errors. To prevent these errors, use only an appropriate version for your platform.
| Platform | Supported Windows Server version |
|---|---|
| Amazon Web Services (AWS) | Windows Server 2022, OS Build 20348.681 or later |
| Microsoft Azure |
|
| VMware vSphere | Windows Server 2022, OS Build 20348.681 or later |
| Google Cloud Platform (GCP) | Windows Server 2022, OS Build 20348.681 or later |
| Bare metal or provider agnostic |
|
2.7.4. 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.
The WMCO does not support OVN-Kubernetes without hybrid networking or OpenShift SDN.
Table 2.1. 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 |
| Google Cloud Platform (GCP) | Hybrid networking with OVN-Kubernetes |
| Bare metal or provider agnostic | Hybrid networking with OVN-Kubernetes |
2.8. Known limitations
Note the following limitations when working with Windows nodes managed by the WMCO (Windows nodes):
The following OpenShift Container Platform features are not supported on Windows nodes:
- Image builds
- OpenShift Pipelines
- OpenShift Service Mesh
- OpenShift monitoring of user-defined projects
- OpenShift Serverless
- Horizontal Pod Autoscaling
- Vertical Pod Autoscaling
The following Red Hat features are not supported on Windows nodes:
- Windows nodes do not support pulling container images from private registries. You can use images from public registries or pre-pull the images.
- Windows nodes do not support workloads created by using deployment configs. You can use a deployment or other method to deploy workloads.
- Windows nodes are not supported in clusters that use a cluster-wide proxy. This is because the WMCO is not able to route traffic through the proxy connection for the workloads.
- Windows nodes are not supported in clusters that are in a disconnected environment.
- Red Hat OpenShift support for Windows Containers does not support adding Windows nodes to a cluster through a trunk port. The only supported networking configuration for adding Windows nodes is through an access port that carries traffic for the VLAN.
- Red Hat OpenShift support for Windows Containers supports only in-tree storage drivers for all cloud providers.
Kubernetes has identified the following node feature limitations :
- Huge pages are not supported for Windows containers.
- Privileged containers are not supported for Windows containers.
- Kubernetes has identified several API compatibility issues.
