Chapter 16. Installation configuration

16.1. Supported installation methods for different platforms

You can perform different types of installations on different platforms.

Note

Not all installation options are supported for all platforms, as shown in the following tables.

Table 16.1. Installer-provisioned infrastructure options

 AWSAzureGCPOpenStackRHVBare metalvSphereVMCIBM ZIBM Power

Default

X

X

X

 

X

X

X

X

  

Custom

X

X

X

X

X

 

X

X

  

Network Operator

X

X

X

   

X

X

  

Restricted network

X

 

X

X

  

X

X

  

Private clusters

X

X

X

       

Existing virtual private networks

X

X

X

       

Government regions

X

X

        

Table 16.2. User-provisioned infrastructure options

 AWSAzureGCPOpenStackRHVBare metalvSphereVMCIBM ZIBM Power

Custom

X

X

X

X

X

X

X

X

X

X

Network Operator

     

X

X

X

  

Restricted network

X

 

X

  

X

X

X

X

X

Shared VPC hosted outside of cluster project

  

X

       

16.2. Customizing nodes

Although directly making changes to OpenShift Container Platform nodes is discouraged, there are times when it is necessary to implement a required low-level security, networking, or performance feature. Direct changes to OpenShift Container Platform nodes can be done by:

  • Creating machine configs that are included in manifest files to start up a cluster during openshift-install.
  • Creating machine configs that are passed to running OpenShift Container Platform nodes via the Machine Config Operator.

The following sections describe features that you might want to configure on your nodes in this way.

16.2.1. Adding day-1 kernel arguments

Although it is often preferable to modify kernel arguments as a day-2 activity, you might want to add kernel arguments to all master or worker nodes during initial cluster installation. Here are some reasons you might want to add kernel arguments during cluster installation so they take effect before the systems first boot up:

  • You want to disable a feature, such as SELinux, so it has no impact on the systems when they first come up.
  • You need to do some low-level network configuration before the systems start.

To add kernel arguments to master or worker nodes, you can create a MachineConfig object and inject that object into the set of manifest files used by Ignition during cluster setup.

For a listing of arguments you can pass to a RHEL 8 kernel at boot time, see Kernel.org kernel parameters. It is best to only add kernel arguments with this procedure if they are needed to complete the initial OpenShift Container Platform installation.

Procedure

  1. Change to the directory that contains the installation program and generate the Kubernetes manifests for the cluster:

    $ ./openshift-install create manifests --dir=<installation_directory>
  2. Decide if you want to add kernel arguments to worker or control plane nodes (also known as the master nodes).
  3. In the openshift directory, create a file (for example, 99-openshift-machineconfig-master-kargs.yaml) to define a MachineConfig object to add the kernel settings. This example adds a loglevel=7 kernel argument to control plane nodes:

    $ cat << EOF > 99-openshift-machineconfig-master-kargs.yaml
    apiVersion: machineconfiguration.openshift.io/v1
    kind: MachineConfig
    metadata:
      labels:
        machineconfiguration.openshift.io/role: master
      name: 99-openshift-machineconfig-master-kargs
    spec:
      kernelArguments:
        - 'loglevel=7'
    EOF

    You can change master to worker to add kernel arguments to worker nodes instead. Create a separate YAML file to add to both master and worker nodes.

You can now continue on to create the cluster.

16.2.2. Adding kernel modules to nodes

For most common hardware, the Linux kernel includes the device driver modules needed to use that hardware when the computer starts up. For some hardware, however, modules are not available in Linux. Therefore, you must find a way to provide those modules to each host computer. This procedure describes how to do that for nodes in an OpenShift Container Platform cluster.

When a kernel module is first deployed by following these instructions, the module is made available for the current kernel. If a new kernel is installed, the kmods-via-containers software will rebuild and deploy the module so a compatible version of that module is available with the new kernel.

The way that this feature is able to keep the module up to date on each node is by:

  • Adding a systemd service to each node that starts at boot time to detect if a new kernel has been installed and
  • If a new kernel is detected, the service rebuilds the module and installs it to the kernel

For information on the software needed for this procedure, see the kmods-via-containers github site.

A few important issues to keep in mind:

  • This procedure is Technology Preview.
  • Software tools and examples are not yet available in official RPM form and can only be obtained for now from unofficial github.com sites noted in the procedure.
  • Third-party kernel modules you might add through these procedures are not supported by Red Hat.
  • In this procedure, the software needed to build your kernel modules is deployed in a RHEL 8 container. Keep in mind that modules are rebuilt automatically on each node when that node gets a new kernel. For that reason, each node needs access to a yum repository that contains the kernel and related packages needed to rebuild the module. That content is best provided with a valid RHEL subscription.

16.2.2.1. Building and testing the kernel module container

Before deploying kernel modules to your OpenShift Container Platform cluster, you can test the process on a separate RHEL system. Gather the kernel module’s source code, the KVC framework, and the kmod-via-containers software. Then build and test the module. To do that on a RHEL 8 system, do the following:

Procedure

  1. Register a RHEL 8 system:

    # subscription-manager register
  2. Attach a subscription to the RHEL 8 system:

    # subscription-manager attach --auto
  3. Install software that is required to build the software and container:

    # yum install podman make git -y
  4. Clone the kmod-via-containers repository:

    1. Create a folder for the repository:

      $ mkdir kmods; cd kmods
    2. Clone the repository:

      $ git clone https://github.com/kmods-via-containers/kmods-via-containers
  5. Install a KVC framework instance on your RHEL 8 build host to test the module. This adds a kmods-via-container systemd service and loads it:

    1. Change to the kmod-via-containers directory:

      $ cd kmods-via-containers/
    2. Install the KVC framework instance:

      $ sudo make install
    3. Reload the systemd manager configuration:

      $ sudo systemctl daemon-reload
  6. Get the kernel module source code. The source code might be used to build a third-party module that you do not have control over, but is supplied by others. You will need content similar to the content shown in the kvc-simple-kmod example that can be cloned to your system as follows:

    $ cd .. ; git clone https://github.com/kmods-via-containers/kvc-simple-kmod
  7. Edit the configuration file, simple-kmod.conf file, in this example, and change the name of the Dockerfile to Dockerfile.rhel:

    1. Change to the kvc-simple-kmod directory:

      $ cd kvc-simple-kmod
    2. Rename the Dockerfile:

      $ cat simple-kmod.conf

      Example Dockerfile

      KMOD_CONTAINER_BUILD_CONTEXT="https://github.com/kmods-via-containers/kvc-simple-kmod.git"
      KMOD_CONTAINER_BUILD_FILE=Dockerfile.rhel
      KMOD_SOFTWARE_VERSION=dd1a7d4
      KMOD_NAMES="simple-kmod simple-procfs-kmod"

  8. Create an instance of kmods-via-containers@.service for your kernel module, simple-kmod in this example:

    $ sudo make install
  9. Enable the kmods-via-containers@.service instance:

    $ sudo kmods-via-containers build simple-kmod $(uname -r)
  10. Enable and start the systemd service:

    $ sudo systemctl enable kmods-via-containers@simple-kmod.service --now
    1. Review the service status:

      $ sudo systemctl status kmods-via-containers@simple-kmod.service

      Example output

      ● kmods-via-containers@simple-kmod.service - Kmods Via Containers - simple-kmod
         Loaded: loaded (/etc/systemd/system/kmods-via-containers@.service;
                enabled; vendor preset: disabled)
         Active: active (exited) since Sun 2020-01-12 23:49:49 EST; 5s ago...

  11. To confirm that the kernel modules are loaded, use the lsmod command to list the modules:

    $ lsmod | grep simple_

    Example output

    simple_procfs_kmod     16384  0
    simple_kmod            16384  0

  12. Optional. Use other methods to check that the simple-kmod example is working:

    • Look for a "Hello world" message in the kernel ring buffer with dmesg:

      $ dmesg | grep 'Hello world'

      Example output

      [ 6420.761332] Hello world from simple_kmod.

    • Check the value of simple-procfs-kmod in /proc:

      $ sudo cat /proc/simple-procfs-kmod

      Example output

      simple-procfs-kmod number = 0

    • Run the spkut command to get more information from the module:

      $ sudo spkut 44

      Example output

      KVC: wrapper simple-kmod for 4.18.0-147.3.1.el8_1.x86_64
      Running userspace wrapper using the kernel module container...
      + podman run -i --rm --privileged
         simple-kmod-dd1a7d4:4.18.0-147.3.1.el8_1.x86_64 spkut 44
      simple-procfs-kmod number = 0
      simple-procfs-kmod number = 44

Going forward, when the system boots this service will check if a new kernel is running. If there is a new kernel, the service builds a new version of the kernel module and then loads it. If the module is already built, it will just load it.

16.2.2.2. Provisioning a kernel module to OpenShift Container Platform

Depending on whether or not you must have the kernel module in place when OpenShift Container Platform cluster first boots, you can set up the kernel modules to be deployed in one of two ways:

  • Provision kernel modules at cluster install time (day-1): You can create the content as a MachineConfig object and provide it to openshift-install by including it with a set of manifest files.
  • Provision kernel modules via Machine Config Operator (day-2): If you can wait until the cluster is up and running to add your kernel module, you can deploy the kernel module software via the Machine Config Operator (MCO).

In either case, each node needs to be able to get the kernel packages and related software packages at the time that a new kernel is detected. There are a few ways you can set up each node to be able to obtain that content.

  • Provide RHEL entitlements to each node.
  • Get RHEL entitlements from an existing RHEL host, from the /etc/pki/entitlement directory and copy them to the same location as the other files you provide when you build your Ignition config.
  • Inside the Dockerfile, add pointers to a yum repository containing the kernel and other packages. This must include new kernel packages as they are needed to match newly installed kernels.
16.2.2.2.1. Provision kernel modules via a MachineConfig object

By packaging kernel module software with a MachineConfig object, you can deliver that software to worker or master nodes at installation time or via the Machine Config Operator.

First create a base Ignition config that you would like to use. At installation time, the Ignition config will contain the ssh public key to add to the authorized_keys file for the core user on the cluster. To add the MachineConfig object later via the MCO instead, the SSH public key is not required. For both type, the example simple-kmod service creates a systemd unit file, which requires a kmods-via-containers@simple-kmod.service.

Note

The systemd unit is a workaround for an upstream bug and makes sure that the kmods-via-containers@simple-kmod.service gets started on boot:

  1. Register a RHEL 8 system:

    # subscription-manager register
  2. Attach a subscription to the RHEL 8 system:

    # subscription-manager attach --auto
  3. Install software needed to build the software:

    # yum install podman make git -y
  4. Create an Ignition config file that creates a systemd unit file:

    1. Create a directory to host the Ignition config file:

      $ mkdir kmods; cd kmods
    2. Create the Ignition config file that creates a systemd unit file:

      $ cat <<EOF > ./baseconfig.ign
      {
        "ignition": { "version": "3.1.0" },
        "passwd": {
          "users": [
            {
              "name": "core",
              "groups": ["sudo"],
              "sshAuthorizedKeys": [
                "ssh-rsa AAAA"
              ]
            }
          ]
        },
        "systemd": {
          "units": [{
            "name": "require-kvc-simple-kmod.service",
            "enabled": true,
            "contents": "[Unit]\nRequires=kmods-via-containers@simple-kmod.service\n[Service]\nType=oneshot\nExecStart=/usr/bin/true\n\n[Install]\nWantedBy=multi-user.target"
          }]
        }
      }
      EOF
      Note

      You must add your public SSH key to the baseconfig.ign file to use the file during openshift-install. The public SSH key is not needed if you create the MachineConfig object using the MCO.

  5. Create a base MCO YAML snippet that uses the following configuration:

    $ cat <<EOF > mc-base.yaml
    apiVersion: machineconfiguration.openshift.io/v1
    kind: MachineConfig
    metadata:
      labels:
        machineconfiguration.openshift.io/role: worker
      name: 10-kvc-simple-kmod
    spec:
      config:
    EOF
    Note

    The mc-base.yaml is set to deploy the kernel module on worker nodes. To deploy on master nodes, change the role from worker to master. To do both, you could repeat the whole procedure using different file names for the two types of deployments.

  6. Get the kmods-via-containers software:

    1. Clone the kmods-via-containers repository:

      $ git clone https://github.com/kmods-via-containers/kmods-via-containers
    2. Clone the kvc-simple-kmod repository:

      $ git clone https://github.com/kmods-via-containers/kvc-simple-kmod
  7. Get your module software. In this example, kvc-simple-kmod is used:
  8. Create a fakeroot directory and populate it with files that you want to deliver via Ignition, using the repositories cloned earlier:

    1. Create the directory:

      $ FAKEROOT=$(mktemp -d)
    2. Change to the kmod-via-containers directory:

      $ cd kmods-via-containers
    3. Install the KVC framework instance:

      $ make install DESTDIR=${FAKEROOT}/usr/local CONFDIR=${FAKEROOT}/etc/
    4. Change to the kvc-simple-kmod directory:

      $ cd ../kvc-simple-kmod
    5. Create the instance:

      $ make install DESTDIR=${FAKEROOT}/usr/local CONFDIR=${FAKEROOT}/etc/
  9. Get a tool called filetranspiler and dependent software:

    $ cd .. ; sudo yum install -y python3
    git clone https://github.com/ashcrow/filetranspiler.git
  10. Generate a final machine config YAML (mc.yaml) and have it include the base Ignition config, base machine config, and the fakeroot directory with files you would like to deliver:

    $ ./filetranspiler/filetranspile -i ./baseconfig.ign \
         -f ${FAKEROOT} --format=yaml --dereference-symlinks \
         | sed 's/^/     /' | (cat mc-base.yaml -) > 99-simple-kmod.yaml
  11. If the cluster is not up yet, generate manifest files and add this file to the openshift directory. If the cluster is already running, apply the file as follows:

    $ oc create -f 99-simple-kmod.yaml

    Your nodes will start the kmods-via-containers@simple-kmod.service service and the kernel modules will be loaded.

  12. To confirm that the kernel modules are loaded, you can log in to a node (using oc debug node/<openshift-node>, then chroot /host). To list the modules, use the lsmod command:

    $ lsmod | grep simple_

    Example output

    simple_procfs_kmod     16384  0
    simple_kmod            16384  0

16.2.3. Encrypting disks during installation

During OpenShift Container Platform installation, you can enable disk encryption on all master and worker nodes. This feature:

  • Is available for installer-provisioned infrastructure and user-provisioned infrastructure deployments
  • Is supported on Red Hat Enterprise Linux CoreOS (RHCOS) systems only
  • Sets up disk encryption during the manifest installation phase so all data written to disk, from first boot forward, is encrypted
  • Encrypts data on the root filesystem only (/dev/mapper/coreos-luks-root on /)
  • Requires no user intervention for providing passphrases
  • Uses AES-256-CBC encryption

There are two different supported encryption modes:

  • TPM v2: This is the preferred mode. TPM v2 stores passphrases in a secure cryptoprocessor. To implement TPM v2 disk encryption, create an Ignition config file as described below.
  • Tang: To use Tang to encrypt your cluster, you need to use a Tang server. Clevis implements decryption on the client side.
Important

The use of Tang encryption mode to encrypt your disks is only supported for bare metal and vSphere installations on user-provisioned infrastructure.

Follow one of the two procedures to enable disk encryption for the nodes in your cluster.

16.2.3.1. Enabling TPM v2 disk encryption

Use this procedure to enable TPM v2 mode disk encryption during OpenShift Container Platform deployment.

Procedure

  1. Check to see if TPM v2 encryption needs to be enabled in the BIOS on each node. This is required on most Dell systems. Check the manual for your computer.
  2. Change to the directory that contains the installation program and generate the Kubernetes manifests for the cluster:

    $ ./openshift-install create manifests --dir=<installation_directory>
  3. In the openshift directory, create master or worker files to encrypt disks for those nodes.

    • To create a worker file, run the following command:

      $ cat << EOF > ./99-openshift-worker-tpmv2-encryption.yaml
      apiVersion: machineconfiguration.openshift.io/v1
      kind: MachineConfig
      metadata:
        name: worker-tpm
        labels:
          machineconfiguration.openshift.io/role: worker
      spec:
        config:
          ignition:
            version: 3.1.0
          storage:
            files:
            - contents:
                source: data:text/plain;base64,e30K
              mode: 420
              overwrite: true
              path: /etc/clevis.json
      EOF
    • To create a master file, run the following command:

      $ cat << EOF > ./99-openshift-master-tpmv2-encryption.yaml
      apiVersion: machineconfiguration.openshift.io/v1
      kind: MachineConfig
      metadata:
        name: master-tpm
        labels:
          machineconfiguration.openshift.io/role: master
      spec:
        config:
          ignition:
            version: 3.1.0
          storage:
            files:
            - contents:
                source: data:text/plain;base64,e30K
              mode: 420
              overwrite: true
              path: /etc/clevis.json
      EOF
  4. Make a backup copy of the YAML file. You should do this because the file will be deleted when you create the cluster.
  5. Continue with the remainder of the OpenShift Container Platform deployment.

16.2.3.2. Enabling Tang disk encryption

Use this procedure to enable Tang mode disk encryption during OpenShift Container Platform deployment.

Procedure

  1. Access a Red Hat Enterprise Linux server from which you can configure the encryption settings and run openshift-install to install a cluster and oc to work with it.
  2. Set up or access an existing Tang server. See Network-bound disk encryption for instructions. See Securing Automated Decryption New Cryptography and Techniques for a presentation on Tang.
  3. Add kernel arguments to configure networking when you do the Red Hat Enterprise Linux CoreOS (RHCOS) installations for your cluster. For example, to configure DHCP networking, identify ip=dhcp, or set static networking when you add parameters to the kernel command line. For both DHCP and static networking, you also must provide the rd.neednet=1 kernel argument.
Important

Skipping this step causes the second boot to fail.

  1. Install the clevis package, if it is not already installed:
$ sudo yum install clevis -y
  1. Generate a thumbprint from the Tang server.

    1. In the following command, replace the value of url with the Tang server URL:

      $ echo nifty random wordwords \
           | clevis-encrypt-tang \
             '{"url":"https://tang.example.org"}'

      Example output

      The advertisement contains the following signing keys:
      
      PLjNyRdGw03zlRoGjQYMahSZGu9

    2. When the Do you wish to trust these keys? [ynYN] prompt displays, type Y, and the thumbprint is displayed:

      Example output

      eyJhbmc3SlRyMXpPenc3ajhEQ01tZVJiTi1oM...

  2. Create a Base64 encoded file, replacing the URL of the Tang server (url) and thumbprint (thp) you just generated:

    $ (cat <<EOM
    {
     "url": "https://tang.example.com",
     "thp": "PLjNyRdGw03zlRoGjQYMahSZGu9"
    }
    EOM
    ) | base64 -w0

    Example output

    ewogInVybCI6ICJodHRwczovL3RhbmcuZXhhbXBsZS5jb20iLAogInRocCI6ICJaUk1leTFjR3cwN3psVExHYlhuUWFoUzBHdTAiCn0K

  3. In the openshift directory, create master or worker files to encrypt disks for those nodes.

    • For worker nodes, use the following command:

      $ cat << EOF > ./99-openshift-worker-tang-encryption.yaml
      apiVersion: machineconfiguration.openshift.io/v1
      kind: MachineConfig
      metadata:
        name: worker-tang
        labels:
          machineconfiguration.openshift.io/role: worker
      spec:
        config:
          ignition:
            version: 3.1.0
          storage:
            files:
            - contents:
                source: data:text/plain;base64,e30K
                source: data:text/plain;base64,ewogInVybCI6ICJodHRwczovL3RhbmcuZXhhbXBsZS5jb20iLAogInRocCI6ICJaUk1leTFjR3cwN3psVExHYlhuUWFoUzBHdTAiCn0K
              mode: 420
              overwrite: true
              path: /etc/clevis.json
      EOF
    • For master nodes, use the following command:

      $ cat << EOF > ./99-openshift-master-tang-encryption.yaml
      apiVersion: machineconfiguration.openshift.io/v1
      kind: MachineConfig
      metadata:
        name: master-tang
        labels:
          machineconfiguration.openshift.io/role: master
      spec:
        config:
          ignition:
            version: 3.1.0
          storage:
            files:
            - contents:
                source: data:text/plain;base64,e30K
                source: data:text/plain;base64,ewogInVybCI6ICJodHRwczovL3RhbmcuZXhhbXBsZS5jb20iLAogInRocCI6ICJaUk1leTFjR3cwN3psVExHYlhuUWFoUzBHdTAiCn0K
              mode: 420
              overwrite: true
              path: /etc/clevis.json
      EOF
  4. Add the rd.neednet=1 kernel argument, as shown in the following example:

      apiVersion: machineconfiguration.openshift.io/v1
      kind: MachineConfig
      metadata:
        name: <node_type>-tang <.>
      spec:
        config:
          ignition:
            version: 3.1.0
        kernelArguments:
          - rd.neednet=1 <.>
    Use the name you defined in the previous examples based on the type of node you are configuring, for example: name: worker-tang.
    Required.
  5. Continue with the remainder of the OpenShift Container Platform deployment.

16.2.4. Configuring chrony time service

You can set the time server and related settings used by the chrony time service (chronyd) by modifying the contents of the chrony.conf file and passing those contents to your nodes as a machine config.

Procedure

  1. Create the contents of the chrony.conf file and encode it as base64. For example:

    $ cat << EOF | base64
        pool 0.rhel.pool.ntp.org iburst 1
        driftfile /var/lib/chrony/drift
        makestep 1.0 3
        rtcsync
        logdir /var/log/chrony
    EOF
    1
    Specify any valid, reachable time source, such as the one provided by your DHCP server. Alternately, you can specify any of the following NTP servers: 1.rhel.pool.ntp.org, 2.rhel.pool.ntp.org, or 3.rhel.pool.ntp.org.

    Example output

    ICAgIHNlcnZlciBjbG9jay5yZWRoYXQuY29tIGlidXJzdAogICAgZHJpZnRmaWxlIC92YXIvbGli
    L2Nocm9ueS9kcmlmdAogICAgbWFrZXN0ZXAgMS4wIDMKICAgIHJ0Y3N5bmMKICAgIGxvZ2RpciAv
    dmFyL2xvZy9jaHJvbnkK

  2. Create the MachineConfig object file, replacing the base64 string with the one you just created. This example adds the file to master nodes. You can change it to worker or make an additional MachineConfig for the worker role. Create MachineConfig files for each type of machine that your cluster uses:

    $ cat << EOF > ./99-masters-chrony-configuration.yaml
    apiVersion: machineconfiguration.openshift.io/v1
    kind: MachineConfig
    metadata:
      labels:
        machineconfiguration.openshift.io/role: master
      name: 99-masters-chrony-configuration
    spec:
      config:
        ignition:
          config: {}
          security:
            tls: {}
          timeouts: {}
          version: 3.1.0
        networkd: {}
        passwd: {}
        storage:
          files:
          - contents:
              source: data:text/plain;charset=utf-8;base64,ICAgIHNlcnZlciBjbG9jay5yZWRoYXQuY29tIGlidXJzdAogICAgZHJpZnRmaWxlIC92YXIvbGliL2Nocm9ueS9kcmlmdAogICAgbWFrZXN0ZXAgMS4wIDMKICAgIHJ0Y3N5bmMKICAgIGxvZ2RpciAvdmFyL2xvZy9jaHJvbnkK
            mode: 420
            overwrite: true
            path: /etc/chrony.conf
      osImageURL: ""
    EOF
  3. Make a backup copy of the configuration files.
  4. Apply the configurations in one of two ways:

    • If the cluster is not up yet, after you generate manifest files, add this file to the <installation_directory>/openshift directory, and then continue to create the cluster.
    • If the cluster is already running, apply the file:

      $ oc apply -f ./99-masters-chrony-configuration.yaml

16.2.5. Additional resources

See Support for FIPS cryptography for information on FIPS support.

16.3. Available cluster customizations

You complete most of the cluster configuration and customization after you deploy your OpenShift Container Platform cluster. A number of configuration resources are available.

You modify the configuration resources to configure the major features of the cluster, such as the image registry, networking configuration, image build behavior, and the identity provider.

For current documentation of the settings that you control by using these resources, use the oc explain command, for example oc explain builds --api-version=config.openshift.io/v1

16.3.1. Cluster configuration resources

All cluster configuration resources are globally scoped (not namespaced) and named cluster.

Resource nameDescription

apiserver.config.openshift.io

Provides API server configuration such as certificates and certificate authorities.

authentication.config.openshift.io

Controls the identity provider and authentication configuration for the cluster.

build.config.openshift.io

Controls default and enforced configuration for all builds on the cluster.

console.config.openshift.io

Configures the behavior of the web console interface, including the logout behavior.

featuregate.config.openshift.io

Enables FeatureGates so that you can use Tech Preview features.

image.config.openshift.io

Configures how specific image registries should be treated (allowed, disallowed, insecure, CA details).

ingress.config.openshift.io

Configuration details related to routing such as the default domain for routes.

oauth.config.openshift.io

Configures identity providers and other behavior related to internal OAuth server flows.

project.config.openshift.io

Configures how projects are created including the project template.

proxy.config.openshift.io

Defines proxies to be used by components needing external network access. Note: not all components currently consume this value.

scheduler.config.openshift.io

Configures scheduler behavior such as policies and default node selectors.

16.3.2. Operator configuration resources

These configuration resources are cluster-scoped instances, named cluster, which control the behavior of a specific component as owned by a particular Operator.

Resource nameDescription

consoles.operator.openshift.io

Controls console appearance such as branding customizations

config.imageregistry.operator.openshift.io

Configures internal image registry settings such as public routing, log levels, proxy settings, resource constraints, replica counts, and storage type.

config.samples.operator.openshift.io

Configures the Samples Operator to control which example image streams and templates are installed on the cluster.

16.3.3. Additional configuration resources

These configuration resources represent a single instance of a particular component. In some cases, you can request multiple instances by creating multiple instances of the resource. In other cases, the Operator can use only a specific resource instance name in a specific namespace. Reference the component-specific documentation for details on how and when you can create additional resource instances.

Resource nameInstance nameNamespaceDescription

alertmanager.monitoring.coreos.com

main

openshift-monitoring

Controls the Alertmanager deployment parameters.

ingresscontroller.operator.openshift.io

default

openshift-ingress-operator

Configures Ingress Operator behavior such as domain, number of replicas, certificates, and controller placement.

16.3.4. Informational Resources

You use these resources to retrieve information about the cluster. Do not edit these resources directly.

Resource nameInstance nameDescription

clusterversion.config.openshift.io

version

In OpenShift Container Platform 4.6, you must not customize the ClusterVersion resource for production clusters. Instead, follow the process to update a cluster.

dns.config.openshift.io

cluster

You cannot modify the DNS settings for your cluster. You can view the DNS Operator status.

infrastructure.config.openshift.io

cluster

Configuration details allowing the cluster to interact with its cloud provider.

network.config.openshift.io

cluster

You cannot modify your cluster networking after installation. To customize your network, follow the process to customize networking during installation.

16.3.5. Updating the global cluster pull secret

You can update the global pull secret for your cluster by either replacing the current pull secret or appending a new pull secret.

Warning

Cluster resources must adjust to the new pull secret, which can temporarily limit the usability of the cluster.

Warning

Updating the global pull secret will cause node reboots while the Machine Config Operator (MCO) syncs the changes.

Prerequisites

  • You have access to the cluster as a user with the cluster-admin role.

Procedure

  1. Optional: To append a new pull secret to the existing pull secret, complete the following steps:

    1. Enter the following command to download the pull secret:

      $ oc get secret/pull-secret -n openshift-config --template='{{index .data ".dockerconfigjson" | base64decode}}' ><pull_secret_location> 1
      1
      Provide the path to the pull secret file.
    2. Enter the following command to add the new pull secret:

      $ oc registry login --registry="<registry>" \ 1
      --auth-basic="<username>:<password>" \ 2
      --to=<pull_secret_location> 3
      1
      Provide the new registry.
      2
      Provide the credentials of the new registry.
      3
      Provide the path to the pull secret file.

      Alternatively, you can perform a manual update to the pull secret file.

  2. Enter the following command to update the global pull secret for your cluster:

    $ oc set data secret/pull-secret -n openshift-config --from-file=.dockerconfigjson=<pull_secret_location> 1
    1
    Provide the path to the new pull secret file.

This update is rolled out to all nodes, which can take some time depending on the size of your cluster. During this time, nodes are drained and pods are rescheduled on the remaining nodes.

16.4. Configuring your firewall

If you use a firewall, you must configure it so that OpenShift Container Platform can access the sites that it requires to function. You must always grant access to some sites, and you grant access to more if you use Red Hat Insights, the Telemetry service, a cloud to host your cluster, and certain build strategies.

16.4.1. Configuring your firewall for OpenShift Container Platform

Before you install OpenShift Container Platform, you must configure your firewall to grant access to the sites that OpenShift Container Platform requires.

There are no special configuration considerations for services running on only controller nodes versus worker nodes.

Procedure

  1. Allowlist the following registry URLs:

    URLPortFunction

    registry.redhat.io

    443, 80

    Provides core container images

    quay.io

    443, 80

    Provides core container images

    *.quay.io

    443, 80

    Provides core container images

    sso.redhat.com

    443, 80

    The https://cloud.redhat.com/openshift site uses authentication from sso.redhat.com

    openshift.org

    443, 80

    Provides Red Hat Enterprise Linux CoreOS (RHCOS) images

    When you add a site, such as quay.io, to your allowlist, do not add a wildcard entry, such as *.quay.io, to your denylist. In most cases, image registries use a content delivery network (CDN) to serve images. If a firewall blocks access, then image downloads are denied when the initial download request is redirected to a host name such as cdn01.quay.io.

    CDN host names, such as cdn01.quay.io, are covered when you add a wildcard entry, such as *.quay.io, in your allowlist.

  2. Allowlist any site that provides resources for a language or framework that your builds require.
  3. If you do not disable Telemetry, you must grant access to the following URLs to access Red Hat Insights:

    URLPortFunction

    cert-api.access.redhat.com

    443, 80

    Required for Telemetry

    api.access.redhat.com

    443, 80

    Required for Telemetry

    infogw.api.openshift.com

    443, 80

    Required for Telemetry

    https://cloud.redhat.com/api/ingress

    443, 80

    Required for Telemetry and for insights-operator

  4. If you use Amazon Web Services (AWS), Microsoft Azure, or Google Cloud Platform (GCP) to host your cluster, you must grant access to the URLs that provide the cloud provider API and DNS for that cloud:

    CloudURLPortFunction

    AWS

    *.amazonaws.com

    443, 80

    Required to access AWS services and resources. Review the AWS Service Endpoints in the AWS documentation to determine the exact endpoints to allow for the regions that you use.

    oso-rhc4tp-docker-registry.s3-us-west-2.amazonaws.com

    443, 80

    Required to access AWS services and resources when using strict security requirements. Review the AWS Service Endpoints in the AWS documentation to determine the exact endpoints to allow for the regions that you use.

    GCP

    *.googleapis.com

    443, 80

    Required to access GCP services and resources. Review Cloud Endpoints in the GCP documentation to determine the endpoints to allow for your APIs.

    accounts.google.com

    443, 80

    Required to access your GCP account.

    Azure

    management.azure.com

    443, 80

    Required to access Azure services and resources. Review the Azure REST API Reference in the Azure documentation to determine the endpoints to allow for your APIs.

  5. Allowlist the following URLs:

    URLPortFunction

    mirror.openshift.com

    443, 80

    Required to access mirrored installation content and images. This site is also a source of release image signatures, although the Cluster Version Operator needs only a single functioning source.

    storage.googleapis.com/openshift-release

    443, 80

    A source of release image signatures, although the Cluster Version Operator needs only a single functioning source.

    *.apps.<cluster_name>.<base_domain>

    443, 80

    Required to access the default cluster routes unless you set an ingress wildcard during installation.

    quay-registry.s3.amazonaws.com

    443, 80

    Required to access Quay image content in AWS.

    api.openshift.com

    443, 80

    Required to check if updates are available for the cluster.

    art-rhcos-ci.s3.amazonaws.com

    443, 80

    Required to download Red Hat Enterprise Linux CoreOS (RHCOS) images.

    api.openshift.com

    443, 80

    Required for your cluster token.

    cloud.redhat.com/openshift

    443, 80

    Required for your cluster token.

    registry.access.redhat.com

    443, 80

    Required for odo CLI.

    Operators require route access to perform health checks. Specifically, the authentication and web console Operators connect to two routes to verify that the routes work. If you are the cluster administrator and do not want to allow *.apps.<cluster_name>.<base_domain>, then allow these routes:

    • oauth-openshift.apps.<cluster_name>.<base_domain>
    • console-openshift-console.apps.<cluster_name>.<base_domain>, or the host name that is specified in the spec.route.hostname field of the consoles.operator/cluster object if the field is not empty.
  6. If you use a default Red Hat Network Time Protocol (NTP) server allow the following URLs:

    • 1.rhel.pool.ntp.org
    • 2.rhel.pool.ntp.org
    • 3.rhel.pool.ntp.org
Note

If you do not use a default Red Hat NTP server, verify the NTP server for your platform and allow it in your firewall.

16.5. Configuring a private cluster

After you install an OpenShift Container Platform version 4.6 cluster, you can set some of its core components to be private.

Important

You can configure this change for only clusters that use infrastructure that you provision to a cloud provider.

16.5.1. About private clusters

By default, OpenShift Container Platform is provisioned using publicly-accessible DNS and endpoints. You can set the DNS, Ingress Controller, and API server to private after you deploy your cluster.

DNS

If you install OpenShift Container Platform on installer-provisioned infrastructure, the installation program creates records in a pre-existing public zone and, where possible, creates a private zone for the cluster’s own DNS resolution. In both the public zone and the private zone, the installation program or cluster creates DNS entries for *.apps, for the Ingress object, and api, for the API server.

The *.apps records in the public and private zone are identical, so when you delete the public zone, the private zone seamlessly provides all DNS resolution for the cluster.

Ingress Controller

Because the default Ingress object is created as public, the load balancer is internet-facing and in the public subnets. You can replace the default Ingress Controller with an internal one.

API server

By default, the installation program creates appropriate network load balancers for the API server to use for both internal and external traffic.

On Amazon Web Services (AWS), separate public and private load balancers are created. The load balancers are identical except that an additional port is available on the internal one for use within the cluster. Although the installation program automatically creates or destroys the load balancer based on API server requirements, the cluster does not manage or maintain them. As long as you preserve the cluster’s access to the API server, you can manually modify or move the load balancers. For the public load balancer, port 6443 is open and the health check is configured for HTTPS against the /readyz path.

On Google Cloud Platform, a single load balancer is created to manage both internal and external API traffic, so you do not need to modify the load balancer.

On Microsoft Azure, both public and private load balancers are created. However, because of limitations in current implementation, you just retain both load balancers in a private cluster.

16.5.2. Setting DNS to private

After you deploy a cluster, you can modify its DNS to use only a private zone.

Procedure

  1. Review the DNS custom resource for your cluster:

    $ oc get dnses.config.openshift.io/cluster -o yaml

    Example output

    apiVersion: config.openshift.io/v1
    kind: DNS
    metadata:
      creationTimestamp: "2019-10-25T18:27:09Z"
      generation: 2
      name: cluster
      resourceVersion: "37966"
      selfLink: /apis/config.openshift.io/v1/dnses/cluster
      uid: 0e714746-f755-11f9-9cb1-02ff55d8f976
    spec:
      baseDomain: <base_domain>
      privateZone:
        tags:
          Name: <infrastructureID>-int
          kubernetes.io/cluster/<infrastructureID>: owned
      publicZone:
        id: Z2XXXXXXXXXXA4
    status: {}

    Note that the spec section contains both a private and a public zone.

  2. Patch the DNS custom resource to remove the public zone:

    $ oc patch dnses.config.openshift.io/cluster --type=merge --patch='{"spec": {"publicZone": null}}'
    dns.config.openshift.io/cluster patched

    Because the Ingress Controller consults the DNS definition when it creates Ingress objects, when you create or modify Ingress objects, only private records are created.

    Important

    DNS records for the existing Ingress objects are not modified when you remove the public zone.

  3. Optional: Review the DNS custom resource for your cluster and confirm that the public zone was removed:

    $ oc get dnses.config.openshift.io/cluster -o yaml

    Example output

    apiVersion: config.openshift.io/v1
    kind: DNS
    metadata:
      creationTimestamp: "2019-10-25T18:27:09Z"
      generation: 2
      name: cluster
      resourceVersion: "37966"
      selfLink: /apis/config.openshift.io/v1/dnses/cluster
      uid: 0e714746-f755-11f9-9cb1-02ff55d8f976
    spec:
      baseDomain: <base_domain>
      privateZone:
        tags:
          Name: <infrastructureID>-int
          kubernetes.io/cluster/<infrastructureID>-wfpg4: owned
    status: {}

16.5.3. Setting the Ingress Controller to private

After you deploy a cluster, you can modify its Ingress Controller to use only a private zone.

Procedure

  1. Modify the default Ingress Controller to use only an internal endpoint:

    $ oc replace --force --wait --filename - <<EOF
    apiVersion: operator.openshift.io/v1
    kind: IngressController
    metadata:
      namespace: openshift-ingress-operator
      name: default
    spec:
      endpointPublishingStrategy:
        type: LoadBalancerService
        loadBalancer:
          scope: Internal
    EOF

    Example output

    ingresscontroller.operator.openshift.io "default" deleted
    ingresscontroller.operator.openshift.io/default replaced

    The public DNS entry is removed, and the private zone entry is updated.

16.5.4. Restricting the API server to private

After you deploy a cluster to Amazon Web Services (AWS) or Microsoft Azure, you can reconfigure the API server to use only the private zone.

Prerequisites

  • Install the OpenShift CLI (oc).
  • Have access to the web console as a user with admin privileges.

Procedure

  1. In the web portal or console for AWS or Azure, take the following actions:

    1. Locate and delete appropriate load balancer component.

      • For AWS, delete the external load balancer. The API DNS entry in the private zone already points to the internal load balancer, which uses an identical configuration, so you do not need to modify the internal load balancer.
      • For Azure, delete the api-internal rule for the load balancer.
    2. Delete the api.$clustername.$yourdomain DNS entry in the public zone.
  2. From your terminal, list the cluster machines:

    $ oc get machine -n openshift-machine-api

    Example output

    NAME                            STATE     TYPE        REGION      ZONE         AGE
    lk4pj-master-0                  running   m4.xlarge   us-east-1   us-east-1a   17m
    lk4pj-master-1                  running   m4.xlarge   us-east-1   us-east-1b   17m
    lk4pj-master-2                  running   m4.xlarge   us-east-1   us-east-1a   17m
    lk4pj-worker-us-east-1a-5fzfj   running   m4.xlarge   us-east-1   us-east-1a   15m
    lk4pj-worker-us-east-1a-vbghs   running   m4.xlarge   us-east-1   us-east-1a   15m
    lk4pj-worker-us-east-1b-zgpzg   running   m4.xlarge   us-east-1   us-east-1b   15m

    You modify the control plane machines, which contain master in the name, in the following step.

  3. Remove the external load balancer from each control plane machine.

    1. Edit a control plane Machine object to remove the reference to the external load balancer.

      $ oc edit machines -n openshift-machine-api <master_name> 1
      1
      Specify the name of the control plane, or master, Machine object to modify.
    2. Remove the lines that describe the external load balancer, which are marked in the following example, and save and exit the object specification:

      ...
      spec:
        providerSpec:
          value:
          ...
            loadBalancers:
            - name: lk4pj-ext 1
              type: network 2
            - name: lk4pj-int
              type: network
      1 2
      Delete this line.
    3. Repeat this process for each of the machines that contains master in the name.