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2.8.2. Private clusters

If your environment does not require an external Internet connection, you can deploy a private OpenShift Container Platform cluster that does not expose external endpoints. Private clusters are accessible from only an internal network and are not visible to the Internet.

By default, OpenShift Container Platform is provisioned to use publicly-accessible DNS and endpoints. A private cluster sets the DNS, Ingress Controller, and API server to private when you deploy your cluster. This means that the cluster resources are only accessible from your internal network and are not visible to the internet.

To deploy a private cluster, you must use existing networking that meets your requirements. Your cluster resources might be shared between other clusters on the network.

Additionally, you must deploy a private cluster from a machine that has access the API services for the cloud you provision to, the hosts on the network that you provision, and to the internet to obtain installation media. You can use any machine that meets these access requirements and follows your company’s guidelines. For example, this machine can be a bastion host on your cloud network or a machine that has access to the network through a VPN. Private clusters in AWS

To create a private cluster on Amazon Web Services (AWS), you must provide an existing private VPC and subnets to host the cluster. The installation program must also be able to resolve the DNS records that the cluster requires. The installation program configures the Ingress Operator and API server for access from only the private network.

The cluster still requires access to Internet to access the AWS APIs.

The following items are not required or created when you install a private cluster:

  • Public subnets
  • Public load balancers, which support public ingress
  • A public Route 53 zone that matches the baseDomain for the cluster

The installation program does use the baseDomain that you specify to create a private Route 53 zone and the required records for the cluster. The cluster is configured so that the Operators do not create public records for the cluster and all cluster machines are placed in the private subnets that you specify. Limitations

The ability to add public functionality to a private cluster is limited.

  • You cannot make the Kubernetes API endpoints public after installation without taking additional actions, including creating public subnets in the VPC for each availability zone in use, creating a public load balancer, and configuring the control plane security groups to allow traffic from Internet on 6443 (Kubernetes API port).
  • If you use a public Service type load balancer, you must tag a public subnet in each availability zone with<cluster-infra-id>: shared so that AWS can use them to create public load balancers.