Last week Amazon announced that support for Windows containers on Elastic Kubernetes Service (EKS) is now generally available. As such, this allows their users to run Windows and Linux containers side by side in the same EKS environment, thus providing a consistent method of provisioning, monitoring, and logging, no matter what type of container they use to host their applications.
With Elastic Kubernetes Service, Amazon provides a managed Kubernetes platform, similar to Azure Kubernetes Service (AKS) and Google Kubernetes Engine (GKE). EKS provides several advantages implemented by most of these cloud providers. These include features such as cross multiple availability zones, detection and recycling of unhealthy nodes, and secure and encrypted communication between the various nodes. Moreover, EKS is fully compatible and certified conformant with Kubernetes, allowing users to run any of their tools and plugins.
Introducing support for Windows containers expands on these capabilities by providing the means to run these side by side with the previously supported Linux containers. To host Windows containers, it is essential to note that the cluster runs on Kubernetes version 1.14 or higher. Currently there is still a minimum of one Linux pod required, running the VPC Resource Controller and VPC Admission Webhook, thereby implementing networking between the various nodes inside the cluster. Additionally, other restrictions apply to the use of Windows containers as well, as described in the official documentation.
- Amazon EC2 instance types C3, C4, D2, I2, M4 (excluding m4.16xlarge), and R3 instances are not supported for Windows workloads.
- Host networking mode is not supported for Windows workloads.
- Amazon EKS clusters must contain 1 or more Linux worker nodes to run core system pods that only run on Linux.
- The kubelet and kube-proxy event logs are redirected to the EKS Windows Event Log and are set to a 200 MB limit.
- Windows worker nodes support one elastic network interface per node.
- Calico network policy enforcement has not been tested with Amazon EKS Windows nodes.
- Group Managed Service Accounts (GMSA) for Windows pods and containers is a Kubernetes 1.14 alpha feature that is not supported by Amazon EKS.
- After you add Windows support to your cluster, you must specify node selectors on your applications so that the pods land on a node with the appropriate operating system.
In the announcement Martin Beeby, principle developer evangelist at Amazon Web Services shows how to start using the new feature. He does this by creating a new cluster, although he mentions the same is available for existing clusters as well. Subsequently, he adds several Windows nodes, followed by deploying a sample application on these running a website in IIS.
