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Installing a private cluster on AWS

In OKD version 4.11, you can install a private cluster into an existing VPC on Amazon Web Services (AWS). The installation program provisions the rest of the required infrastructure, which you can further customize. To customize the installation, you modify parameters in the install-config.yaml file before you install the cluster.

Prerequisites

Private clusters

You can deploy a private OKD 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, OKD 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.

If the cluster has any public subnets, load balancer services created by administrators might be publicly accessible. To ensure cluster security, verify that these services are explicitly annotated as private.

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.

  • Deploy from a machine that has access to:

    • The API services for the cloud to which you provision.

    • The hosts on the network that you provision.

    • 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 the 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 kubernetes.io/cluster/<cluster-infra-id>: shared so that AWS can use them to create public load balancers.

About using a custom VPC

In OKD 4.11, you can deploy a cluster into existing subnets in an existing Amazon Virtual Private Cloud (VPC) in Amazon Web Services (AWS). By deploying OKD into an existing AWS VPC, you might be able to avoid limit constraints in new accounts or more easily abide by the operational constraints that your company’s guidelines set. If you cannot obtain the infrastructure creation permissions that are required to create the VPC yourself, use this installation option.

Because the installation program cannot know what other components are also in your existing subnets, it cannot choose subnet CIDRs and so forth on your behalf. You must configure networking for the subnets that you install your cluster to yourself.

Requirements for using your VPC

The installation program no longer creates the following components:

  • Internet gateways

  • NAT gateways

  • Subnets

  • Route tables

  • VPCs

  • VPC DHCP options

  • VPC endpoints

The installation program requires that you use the cloud-provided DNS server. Using a custom DNS server is not supported and causes the installation to fail.

If you use a custom VPC, you must correctly configure it and its subnets for the installation program and the cluster to use. See Amazon VPC console wizard configurations and Work with VPCs and subnets in the AWS documentation for more information on creating and managing an AWS VPC.

The installation program cannot:

  • Subdivide network ranges for the cluster to use.

  • Set route tables for the subnets.

  • Set VPC options like DHCP.

You must complete these tasks before you install the cluster. See VPC networking components and Route tables for your VPC for more information on configuring networking in an AWS VPC.

Your VPC must meet the following characteristics:

  • The VPC must not use the kubernetes.io/cluster/.*: owned, Name, and openshift.io/cluster tags.

    The installation program modifies your subnets to add the kubernetes.io/cluster/.*: shared tag, so your subnets must have at least one free tag slot available for it. See Tag Restrictions in the AWS documentation to confirm that the installation program can add a tag to each subnet that you specify. You cannot use a Name tag, because it overlaps with the EC2 Name field and the installation fails.

  • You must enable the enableDnsSupport and enableDnsHostnames attributes in your VPC, so that the cluster can use the Route 53 zones that are attached to the VPC to resolve cluster’s internal DNS records. See DNS Support in Your VPC in the AWS documentation.

    If you prefer to use your own Route 53 hosted private zone, you must associate the existing hosted zone with your VPC prior to installing a cluster. You can define your hosted zone using the platform.aws.hostedZone field in the install-config.yaml file.

If you are working in a disconnected environment, you are unable to reach the public IP addresses for EC2, ELB, and S3 endpoints. Depending on the level to which you want to restrict internet traffic during the installation, the following configuration options are available:

Option 1: Create VPC endpoints

Create a VPC endpoint and attach it to the subnets that the clusters are using. Name the endpoints as follows:

  • ec2.<region>.amazonaws.com

  • elasticloadbalancing.<region>.amazonaws.com

  • s3.<region>.amazonaws.com

With this option, network traffic remains private between your VPC and the required AWS services.

Option 2: Create a proxy without VPC endpoints

As part of the installation process, you can configure an HTTP or HTTPS proxy. With this option, internet traffic goes through the proxy to reach the required AWS services.

Option 3: Create a proxy with VPC endpoints

As part of the installation process, you can configure an HTTP or HTTPS proxy with VPC endpoints. Create a VPC endpoint and attach it to the subnets that the clusters are using. Name the endpoints as follows:

  • ec2.<region>.amazonaws.com

  • elasticloadbalancing.<region>.amazonaws.com

  • s3.<region>.amazonaws.com

When configuring the proxy in the install-config.yaml file, add these endpoints to the noProxy field. With this option, the proxy prevents the cluster from accessing the internet directly. However, network traffic remains private between your VPC and the required AWS services.

Required VPC components

You must provide a suitable VPC and subnets that allow communication to your machines.

Component AWS type Description

VPC

  • AWS::EC2::VPC

  • AWS::EC2::VPCEndpoint

You must provide a public VPC for the cluster to use. The VPC uses an endpoint that references the route tables for each subnet to improve communication with the registry that is hosted in S3.

Public subnets

  • AWS::EC2::Subnet

  • AWS::EC2::SubnetNetworkAclAssociation

Your VPC must have public subnets for between 1 and 3 availability zones and associate them with appropriate Ingress rules.

Internet gateway

  • AWS::EC2::InternetGateway

  • AWS::EC2::VPCGatewayAttachment

  • AWS::EC2::RouteTable

  • AWS::EC2::Route

  • AWS::EC2::SubnetRouteTableAssociation

  • AWS::EC2::NatGateway

  • AWS::EC2::EIP

You must have a public internet gateway, with public routes, attached to the VPC. In the provided templates, each public subnet has a NAT gateway with an EIP address. These NAT gateways allow cluster resources, like private subnet instances, to reach the internet and are not required for some restricted network or proxy scenarios.

Network access control

  • AWS::EC2::NetworkAcl

  • AWS::EC2::NetworkAclEntry

You must allow the VPC to access the following ports:

Port

Reason

80

Inbound HTTP traffic

443

Inbound HTTPS traffic

22

Inbound SSH traffic

1024 - 65535

Inbound ephemeral traffic

0 - 65535

Outbound ephemeral traffic

Private subnets

  • AWS::EC2::Subnet

  • AWS::EC2::RouteTable

  • AWS::EC2::SubnetRouteTableAssociation

Your VPC can have private subnets. The provided CloudFormation templates can create private subnets for between 1 and 3 availability zones. If you use private subnets, you must provide appropriate routes and tables for them.

VPC validation

To ensure that the subnets that you provide are suitable, the installation program confirms the following data:

  • All the subnets that you specify exist.

  • You provide private subnets.

  • The subnet CIDRs belong to the machine CIDR that you specified.

  • You provide subnets for each availability zone. Each availability zone contains no more than one public and one private subnet. If you use a private cluster, provide only a private subnet for each availability zone. Otherwise, provide exactly one public and private subnet for each availability zone.

  • You provide a public subnet for each private subnet availability zone. Machines are not provisioned in availability zones that you do not provide private subnets for.

If you destroy a cluster that uses an existing VPC, the VPC is not deleted. When you remove the OKD cluster from a VPC, the kubernetes.io/cluster/.*: shared tag is removed from the subnets that it used.

Division of permissions

Starting with OKD 4.3, you do not need all of the permissions that are required for an installation program-provisioned infrastructure cluster to deploy a cluster. This change mimics the division of permissions that you might have at your company: some individuals can create different resource in your clouds than others. For example, you might be able to create application-specific items, like instances, buckets, and load balancers, but not networking-related components such as VPCs, subnets, or ingress rules.

The AWS credentials that you use when you create your cluster do not need the networking permissions that are required to make VPCs and core networking components within the VPC, such as subnets, routing tables, internet gateways, NAT, and VPN. You still need permission to make the application resources that the machines within the cluster require, such as ELBs, security groups, S3 buckets, and nodes.

Isolation between clusters

If you deploy OKD to an existing network, the isolation of cluster services is reduced in the following ways:

  • You can install multiple OKD clusters in the same VPC.

  • ICMP ingress is allowed from the entire network.

  • TCP 22 ingress (SSH) is allowed to the entire network.

  • Control plane TCP 6443 ingress (Kubernetes API) is allowed to the entire network.

  • Control plane TCP 22623 ingress (MCS) is allowed to the entire network.

Generating a key pair for cluster node SSH access

During an OKD installation, you can provide an SSH public key to the installation program. The key is passed to the Fedora CoreOS (FCOS) nodes through their Ignition config files and is used to authenticate SSH access to the nodes. The key is added to the ~/.ssh/authorized_keys list for the core user on each node, which enables password-less authentication.

After the key is passed to the nodes, you can use the key pair to SSH in to the FCOS nodes as the user core. To access the nodes through SSH, the private key identity must be managed by SSH for your local user.

If you want to SSH in to your cluster nodes to perform installation debugging or disaster recovery, you must provide the SSH public key during the installation process. The ./openshift-install gather command also requires the SSH public key to be in place on the cluster nodes.

Do not skip this procedure in production environments, where disaster recovery and debugging is required.

You must use a local key, not one that you configured with platform-specific approaches such as AWS key pairs.

On clusters running Fedora CoreOS (FCOS), the SSH keys specified in the Ignition config files are written to the /home/core/.ssh/authorized_keys.d/core file. However, the Machine Config Operator manages SSH keys in the /home/core/.ssh/authorized_keys file and configures sshd to ignore the /home/core/.ssh/authorized_keys.d/core file. As a result, newly provisioned OKD nodes are not accessible using SSH until the Machine Config Operator reconciles the machine configs with the authorized_keys file. After you can access the nodes using SSH, you can delete the /home/core/.ssh/authorized_keys.d/core file.
Procedure

  1. If you do not have an existing SSH key pair on your local machine to use for authentication onto your cluster nodes, create one. For example, on a computer that uses a Linux operating system, run the following command:

    $ ssh-keygen -t ed25519 -N '' -f <path>/<file_name> (1)
    1 Specify the path and file name, such as ~/.ssh/id_ed25519, of the new SSH key. If you have an existing key pair, ensure your public key is in the your ~/.ssh directory.

    If you plan to install an OKD cluster that uses FIPS validated or Modules In Process cryptographic libraries on the x86_64 architecture, do not create a key that uses the ed25519 algorithm. Instead, create a key that uses the rsa or ecdsa algorithm.

  2. View the public SSH key:

    $ cat <path>/<file_name>.pub

    For example, run the following to view the ~/.ssh/id_ed25519.pub public key:

    $ cat ~/.ssh/id_ed25519.pub

  3. Add the SSH private key identity to the SSH agent for your local user, if it has not already been added. SSH agent management of the key is required for password-less SSH authentication onto your cluster nodes, or if you want to use the ./openshift-install gather command.

    On some distributions, default SSH private key identities such as ~/.ssh/id_rsa and ~/.ssh/id_dsa are managed automatically.

    1. If the ssh-agent process is not already running for your local user, start it as a background task:

      $ eval "$(ssh-agent -s)"
      Example output
      Agent pid 31874

      If your cluster is in FIPS mode, only use FIPS-compliant algorithms to generate the SSH key. The key must be either RSA or ECDSA.

  4. Add your SSH private key to the ssh-agent:

    $ ssh-add <path>/<file_name> (1)
    1 Specify the path and file name for your SSH private key, such as ~/.ssh/id_ed25519
    Example output
    Identity added: /home/<you>/<path>/<file_name> (<computer_name>)
Next steps

  • When you install OKD, provide the SSH public key to the installation program.

Obtaining the installation program

Before you install OKD, download the installation file on a local computer.

Prerequisites

  • You have a computer that runs Linux or macOS, with 500 MB of local disk space.

Procedure

  1. Download installer from https://github.com/openshift/okd/releases

    The installation program creates several files on the computer that you use to install your cluster. You must keep the installation program and the files that the installation program creates after you finish installing the cluster. Both files are required to delete the cluster.

    Deleting the files created by the installation program does not remove your cluster, even if the cluster failed during installation. To remove your cluster, complete the OKD uninstallation procedures for your specific cloud provider.

  2. Extract the installation program. For example, on a computer that uses a Linux operating system, run the following command:

    $ tar -xvf openshift-install-linux.tar.gz

  3. Download your installation pull secret from the Red Hat OpenShift Cluster Manager. This pull secret allows you to authenticate with the services that are provided by the included authorities, including Quay.io, which serves the container images for OKD components.

    Using a pull secret from the Red Hat OpenShift Cluster Manager is not required. You can use a pull secret for another private registry. Or, if you do not need the cluster to pull images from a private registry, you can use {"auths":{"fake":{"auth":"aWQ6cGFzcwo="}}} as the pull secret when prompted during the installation.

    If you do not use the pull secret from the Red Hat OpenShift Cluster Manager:

    • Red Hat Operators are not available.

    • The Telemetry and Insights operators do not send data to Red Hat.

    • Content from the Red Hat Container Catalog registry, such as image streams and Operators, are not available.

Manually creating the installation configuration file

For installations of a private OKD cluster that are only accessible from an internal network and are not visible to the internet, you must manually generate your installation configuration file.

Prerequisites

  • You have an SSH public key on your local machine to provide to the installation program. The key will be used for SSH authentication onto your cluster nodes for debugging and disaster recovery.

  • You have obtained the OKD installation program and the pull secret for your cluster.

Procedure

  1. Create an installation directory to store your required installation assets in:

    $ mkdir <installation_directory>

    You must create a directory. Some installation assets, like bootstrap X.509 certificates have short expiration intervals, so you must not reuse an installation directory. If you want to reuse individual files from another cluster installation, you can copy them into your directory. However, the file names for the installation assets might change between releases. Use caution when copying installation files from an earlier OKD version.

  2. Customize the sample install-config.yaml file template that is provided and save it in the <installation_directory>.

    You must name this configuration file install-config.yaml.

    For some platform types, you can alternatively run ./openshift-install create install-config --dir <installation_directory> to generate an install-config.yaml file. You can provide details about your cluster configuration at the prompts.

  3. Back up the install-config.yaml file so that you can use it to install multiple clusters.

    The install-config.yaml file is consumed during the next step of the installation process. You must back it up now.

Installation configuration parameters

Before you deploy an OKD cluster, you provide parameter values to describe your account on the cloud platform that hosts your cluster and optionally customize your cluster’s platform. When you create the install-config.yaml installation configuration file, you provide values for the required parameters through the command line. If you customize your cluster, you can modify the install-config.yaml file to provide more details about the platform.

After installation, you cannot modify these parameters in the install-config.yaml file.

Required configuration parameters

Required installation configuration parameters are described in the following table:

Table 1. Required parameters
Parameter Description Values

apiVersion

The API version for the install-config.yaml content. The current version is v1. The installer may also support older API versions.

String

baseDomain

The base domain of your cloud provider. The base domain is used to create routes to your OKD cluster components. The full DNS name for your cluster is a combination of the baseDomain and metadata.name parameter values that uses the <metadata.name>.<baseDomain> format.

A fully-qualified domain or subdomain name, such as example.com.

metadata

Kubernetes resource ObjectMeta, from which only the name parameter is consumed.

Object

metadata.name

The name of the cluster. DNS records for the cluster are all subdomains of {{.metadata.name}}.{{.baseDomain}}.

String of lowercase letters, hyphens (-), and periods (.), such as dev.

platform

The configuration for the specific platform upon which to perform the installation: alibabacloud, aws, baremetal, azure, gcp, ibmcloud, nutanix, openstack, ovirt, vsphere, or {}. For additional information about platform.<platform> parameters, consult the table for your specific platform that follows.

Object

Network configuration parameters

You can customize your installation configuration based on the requirements of your existing network infrastructure. For example, you can expand the IP address block for the cluster network or provide different IP address blocks than the defaults.

Only IPv4 addresses are supported.

Globalnet is not supported with Red Hat OpenShift Data Foundation disaster recovery solutions. For regional disaster recovery scenarios, ensure that you use a nonoverlapping range of private IP addresses for the cluster and service networks in each cluster.
Table 2. Network parameters
Parameter Description Values

networking

The configuration for the cluster network.

Object

You cannot modify parameters specified by the networking object after installation.

networking.networkType

The cluster network provider Container Network Interface (CNI) cluster network provider to install.

Either OpenShiftSDN or OVNKubernetes. The default value is OVNKubernetes.

networking.clusterNetwork

The IP address blocks for pods.

The default value is 10.128.0.0/14 with a host prefix of /23.

If you specify multiple IP address blocks, the blocks must not overlap.

An array of objects. For example:

networking:
  clusterNetwork:
  - cidr: 10.128.0.0/14
    hostPrefix: 23

networking.clusterNetwork.cidr

Required if you use networking.clusterNetwork. An IP address block.

An IPv4 network.

An IP address block in Classless Inter-Domain Routing (CIDR) notation. The prefix length for an IPv4 block is between 0 and 32.

networking.clusterNetwork.hostPrefix

The subnet prefix length to assign to each individual node. For example, if hostPrefix is set to 23 then each node is assigned a /23 subnet out of the given cidr. A hostPrefix value of 23 provides 510 (2^(32 - 23) - 2) pod IP addresses.

A subnet prefix.

The default value is 23.

networking.serviceNetwork

The IP address block for services. The default value is 172.30.0.0/16.

The OpenShift SDN and OVN-Kubernetes network providers support only a single IP address block for the service network.

An array with an IP address block in CIDR format. For example:

networking:
  serviceNetwork:
   - 172.30.0.0/16

networking.machineNetwork

The IP address blocks for machines.

If you specify multiple IP address blocks, the blocks must not overlap.

An array of objects. For example:

networking:
  machineNetwork:
  - cidr: 10.0.0.0/16

networking.machineNetwork.cidr

Required if you use networking.machineNetwork. An IP address block. The default value is 10.0.0.0/16 for all platforms other than libvirt. For libvirt, the default value is 192.168.126.0/24.

An IP network block in CIDR notation.

For example, 10.0.0.0/16.

Set the networking.machineNetwork to match the CIDR that the preferred NIC resides in.

Optional configuration parameters

Optional installation configuration parameters are described in the following table:

Table 3. Optional parameters
Parameter Description Values

additionalTrustBundle

A PEM-encoded X.509 certificate bundle that is added to the nodes' trusted certificate store. This trust bundle may also be used when a proxy has been configured.

String

capabilities

Controls the installation of optional core cluster components. You can reduce the footprint of your OKD cluster by disabling optional components.

String array

capabilities.baselineCapabilitySet

Selects an initial set of optional capabilities to enable. Valid values are None, v4.11 and vCurrent. v4.11 enables the baremetal Operator, the marketplace Operator, and the openshift-samples content. vCurrent installs the recommended set of capabilities for the current version of OKD. The default value is vCurrent.

String

capabilities.additionalEnabledCapabilities

Extends the set of optional capabilities beyond what you specify in baselineCapabilitySet. Valid values are baremetal, marketplace and openshift-samples. You may specify multiple capabilities in this parameter.

String array

cgroupsV2

Enables Linux control groups version 2 (cgroups v2) on specific nodes in your cluster. The OKD process for enabling cgroups v2 disables all cgroup version 1 controllers and hierarchies. The OKD cgroups version 2 feature is in Developer Preview and is not supported by Red Hat at this time.

true

compute

The configuration for the machines that comprise the compute nodes.

Array of MachinePool objects.

compute.architecture

Determines the instruction set architecture of the machines in the pool. Currently, clusters with varied architectures are not supported. All pools must specify the same architecture. Valid values are amd64 (the default). See Supported installation methods for different platforms in Installing documentation for information about instance availability.

String

compute.hyperthreading

Whether to enable or disable simultaneous multithreading, or hyperthreading, on compute machines. By default, simultaneous multithreading is enabled to increase the performance of your machines' cores.

If you disable simultaneous multithreading, ensure that your capacity planning accounts for the dramatically decreased machine performance.

Enabled or Disabled

compute.name

Required if you use compute. The name of the machine pool.

worker

compute.platform

Required if you use compute. Use this parameter to specify the cloud provider to host the worker machines. This parameter value must match the controlPlane.platform parameter value.

alibabacloud, aws, azure, gcp, ibmcloud, nutanix, openstack, ovirt, vsphere, or {}

compute.replicas

The number of compute machines, which are also known as worker machines, to provision.

A positive integer greater than or equal to 2. The default value is 3.

controlPlane

The configuration for the machines that comprise the control plane.

Array of MachinePool objects.