Chapter 1. Customizing nodes OpenShift Container Platform supports both cluster-wide and per-machine configuration via Ignition, which allows arbitrary partitioning and file content changes to the operating system. In general, if a configuration file is documented in Red Hat Enterprise Linux (RHEL), then modifying it via Ignition is supported. There are two ways to deploy machine config changes: 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. Additionally, modifying the reference config, such as the Ignition config that is passed to coreos-installer when installing bare-metal nodes allows per-machine configuration. These changes are currently not visible to the Machine Config Operator. The following sections describe features that you might want to configure on your nodes in this way. 1.1. Creating machine configs with Butane Machine configs are used to configure control plane and worker machines by instructing machines how to create users and file systems, set up the network, install systemd units, and more. Because modifying machine configs can be difficult, you can use Butane configs to create machine configs for you, thereby making node configuration much easier. 1.1.1. About Butane Butane is a command-line utility that OpenShift Container Platform uses to provide convenient, short-hand syntax for writing machine configs, as well as for performing additional validation of machine configs. The format of the Butane config file that Butane accepts is defined in the OpenShift Butane config spec . 1.1.2. Installing Butane You can install the Butane tool ( butane ) to create OpenShift Container Platform machine configs from a command-line interface. You can install butane on Linux, Windows, or macOS by downloading the corresponding binary file. Tip Butane releases are backwards-compatible with older releases and with the Fedora CoreOS Config Transpiler (FCCT). Procedure Navigate to the Butane image download page at https://mirror.openshift.com/pub/openshift-v4/clients/butane/ . Get the butane binary: For the newest version of Butane, save the latest butane image to your current directory: USD curl https://mirror.openshift.com/pub/openshift-v4/clients/butane/latest/butane --output butane Optional: For a specific type of architecture you are installing Butane on, such as aarch64 or ppc64le, indicate the appropriate URL. For example: USD curl https://mirror.openshift.com/pub/openshift-v4/clients/butane/latest/butane-aarch64 --output butane Make the downloaded binary file executable: USD chmod +x butane Move the butane binary file to a directory on your PATH . To check your PATH , open a terminal and execute the following command: USD echo USDPATH Verification steps You can now use the Butane tool by running the butane command: USD butane <butane_file> 1.1.3. Creating a MachineConfig object by using Butane You can use Butane to produce a MachineConfig object so that you can configure worker or control plane nodes at installation time or via the Machine Config Operator. Prerequisites You have installed the butane utility. Procedure Create a Butane config file. The following example creates a file named 99-worker-custom.bu that configures the system console to show kernel debug messages and specifies custom settings for the chrony time service: variant: openshift version: 4.12.0 metadata: name: 99-worker-custom labels: machineconfiguration.openshift.io/role: worker openshift: kernel_arguments: - loglevel=7 storage: files: - path: /etc/chrony.conf mode: 0644 overwrite: true contents: inline: | pool 0.rhel.pool.ntp.org iburst driftfile /var/lib/chrony/drift makestep 1.0 3 rtcsync logdir /var/log/chrony Note The 99-worker-custom.bu file is set to create a machine config for worker nodes. To deploy on control plane 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. Create a MachineConfig object by giving Butane the file that you created in the step: USD butane 99-worker-custom.bu -o ./99-worker-custom.yaml A MachineConfig object YAML file is created for you to finish configuring your machines. Save the Butane config in case you need to update the MachineConfig object in the future. If the cluster is not running yet, generate manifest files and add the MachineConfig object YAML file to the openshift directory. If the cluster is already running, apply the file as follows: USD oc create -f 99-worker-custom.yaml Additional resources Adding kernel modules to nodes Encrypting and mirroring disks during installation 1.2. 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 need to do some low-level network configuration before the systems start. You want to disable a feature, such as SELinux, so it has no impact on the systems when they first come up. Warning Disabling SELinux on RHCOS in production is not supported. Once SELinux has been disabled on a node, it must be re-provisioned before re-inclusion in a production cluster. 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 Change to the directory that contains the installation program and generate the Kubernetes manifests for the cluster: USD ./openshift-install create manifests --dir <installation_directory> Decide if you want to add kernel arguments to worker or control plane nodes. 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: USD 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. 1.3. 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. 1.3.1. 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 Register a RHEL 8 system: # subscription-manager register Attach a subscription to the RHEL 8 system: # subscription-manager attach --auto Install software that is required to build the software and container: # yum install podman make git -y Clone the kmod-via-containers repository: Create a folder for the repository: USD mkdir kmods; cd kmods Clone the repository: USD git clone https://github.com/kmods-via-containers/kmods-via-containers 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: Change to the kmod-via-containers directory: USD cd kmods-via-containers/ Install the KVC framework instance: USD sudo make install Reload the systemd manager configuration: USD sudo systemctl daemon-reload 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: USD cd .. ; git clone https://github.com/kmods-via-containers/kvc-simple-kmod Edit the configuration file, simple-kmod.conf file, in this example, and change the name of the Dockerfile to Dockerfile.rhel : Change to the kvc-simple-kmod directory: USD cd kvc-simple-kmod Rename the Dockerfile: USD 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" Create an instance of kmods-via-containers@.service for your kernel module, simple-kmod in this example: USD sudo make install Enable the kmods-via-containers@.service instance: USD sudo kmods-via-containers build simple-kmod USD(uname -r) Enable and start the systemd service: USD sudo systemctl enable kmods-via-containers@simple-kmod.service --now Review the service status: USD 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... To confirm that the kernel modules are loaded, use the lsmod command to list the modules: USD lsmod | grep simple_ Example output simple_procfs_kmod 16384 0 simple_kmod 16384 0 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 : USD dmesg | grep 'Hello world' Example output [ 6420.761332] Hello world from simple_kmod. Check the value of simple-procfs-kmod in /proc : USD sudo cat /proc/simple-procfs-kmod Example output simple-procfs-kmod number = 0 Run the spkut command to get more information from the module: USD 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. 1.3.2. 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. 1.3.2.1. Provision kernel modules via a MachineConfig object By packaging kernel module software with a MachineConfig object, you can deliver that software to worker or control plane nodes at installation time or via the Machine Config Operator. Procedure Register a RHEL 8 system: # subscription-manager register Attach a subscription to the RHEL 8 system: # subscription-manager attach --auto Install software needed to build the software: # yum install podman make git -y Create a directory to host the kernel module and tooling: USD mkdir kmods; cd kmods Get the kmods-via-containers software: Clone the kmods-via-containers repository: USD git clone https://github.com/kmods-via-containers/kmods-via-containers Clone the kvc-simple-kmod repository: USD git clone https://github.com/kmods-via-containers/kvc-simple-kmod Get your module software. In this example, kvc-simple-kmod is used. Create a fakeroot directory and populate it with files that you want to deliver via Ignition, using the repositories cloned earlier: Create the directory: USD FAKEROOT=USD(mktemp -d) Change to the kmod-via-containers directory: USD cd kmods-via-containers Install the KVC framework instance: USD make install DESTDIR=USD{FAKEROOT}/usr/local CONFDIR=USD{FAKEROOT}/etc/ Change to the kvc-simple-kmod directory: USD cd ../kvc-simple-kmod Create the instance: USD make install DESTDIR=USD{FAKEROOT}/usr/local CONFDIR=USD{FAKEROOT}/etc/ Clone the fakeroot directory, replacing any symbolic links with copies of their targets, by running the following command: USD cd .. && rm -rf kmod-tree && cp -Lpr USD{FAKEROOT} kmod-tree Create a Butane config file, 99-simple-kmod.bu , that embeds the kernel module tree and enables the systemd service. Note See "Creating machine configs with Butane" for information about Butane. variant: openshift version: 4.12.0 metadata: name: 99-simple-kmod labels: machineconfiguration.openshift.io/role: worker 1 storage: trees: - local: kmod-tree systemd: units: - name: kmods-via-containers@simple-kmod.service enabled: true 1 To deploy on control plane nodes, change worker to master . To deploy on both control plane and worker nodes, perform the remainder of these instructions once for each node type. Use Butane to generate a machine config YAML file, 99-simple-kmod.yaml , containing the files and configuration to be delivered: USD butane 99-simple-kmod.bu --files-dir . -o 99-simple-kmod.yaml 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: USD 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. 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: USD lsmod | grep simple_ Example output simple_procfs_kmod 16384 0 simple_kmod 16384 0 1.4. Encrypting and mirroring disks during installation During an OpenShift Container Platform installation, you can enable boot disk encryption and mirroring on the cluster nodes. 1.4.1. About disk encryption You can enable encryption for the boot disks on the control plane and compute nodes at installation time. OpenShift Container Platform supports the Trusted Platform Module (TPM) v2 and Tang encryption modes. TPM v2 This is the preferred mode. TPM v2 stores passphrases in a secure cryptoprocessor on the server. You can use this mode to prevent decryption of the boot disk data on a cluster node if the disk is removed from the server. Tang Tang and Clevis are server and client components that enable network-bound disk encryption (NBDE). You can bind the boot disk data on your cluster nodes to one or more Tang servers. This prevents decryption of the data unless the nodes are on a secure network where the Tang servers are accessible. Clevis is an automated decryption framework used to implement decryption on the client side. Important The use of the Tang encryption mode to encrypt your disks is only supported for bare metal and vSphere installations on user-provisioned infrastructure. In earlier versions of Red Hat Enterprise Linux CoreOS (RHCOS), disk encryption was configured by specifying /etc/clevis.json in the Ignition config. That file is not supported in clusters created with OpenShift Container Platform 4.7 or later. Configure disk encryption by using the following procedure. When the TPM v2 or Tang encryption modes are enabled, the RHCOS boot disks are encrypted using the LUKS2 format. This feature: Is available for installer-provisioned infrastructure, user-provisioned infrastructure, and Assisted Installer deployments For Assisted installer deployments: Each cluster can only have a single encryption method, Tang or TPM Encryption can be enabled on some or all nodes There is no Tang threshold; all servers must be valid and operational Encryption applies to the installation disks only, not to the workload disks Is supported on Red Hat Enterprise Linux CoreOS (RHCOS) systems only Sets up disk encryption during the manifest installation phase, encrypting all data written to disk, from first boot forward Requires no user intervention for providing passphrases Uses AES-256-XTS encryption, or AES-256-CBC if FIPS mode is enabled 1.4.1.1. Configuring an encryption threshold In OpenShift Container Platform, you can specify a requirement for more than one Tang server. You can also configure the TPM v2 and Tang encryption modes simultaneously. This enables boot disk data decryption only if the TPM secure cryptoprocessor is present and the Tang servers are accessible over a secure network. You can use the threshold attribute in your Butane configuration to define the minimum number of TPM v2 and Tang encryption conditions required for decryption to occur. The threshold is met when the stated value is reached through any combination of the declared conditions. For example, the threshold value of 2 in the following configuration can be reached by accessing the two Tang servers, or by accessing the TPM secure cryptoprocessor and one of the Tang servers: Example Butane configuration for disk encryption variant: openshift version: 4.12.0 metadata: name: worker-storage labels: machineconfiguration.openshift.io/role: worker boot_device: layout: x86_64 1 luks: tpm2: true 2 tang: 3 - url: http://tang1.example.com:7500 thumbprint: jwGN5tRFK-kF6pIX89ssF3khxxX - url: http://tang2.example.com:7500 thumbprint: VCJsvZFjBSIHSldw78rOrq7h2ZF threshold: 2 4 openshift: fips: true 1 Set this field to the instruction set architecture of the cluster nodes. Some examples include, x86_64 , aarch64 , or ppc64le . 2 Include this field if you want to use a Trusted Platform Module (TPM) to encrypt the root file system. 3 Include this section if you want to use one or more Tang servers. 4 Specify the minimum number of TPM v2 and Tang encryption conditions required for decryption to occur. Important The default threshold value is 1 . If you include multiple encryption conditions in your configuration but do not specify a threshold, decryption can occur if any of the conditions are met. Note If you require TPM v2 and Tang for decryption, the value of the threshold attribute must equal the total number of stated Tang servers plus one. If the threshold value is lower, it is possible to reach the threshold value by using a single encryption mode. For example, if you set tpm2 to true and specify two Tang servers, a threshold of 2 can be met by accessing the two Tang servers, even if the TPM secure cryptoprocessor is not available. 1.4.2. About disk mirroring During OpenShift Container Platform installation on control plane and worker nodes, you can enable mirroring of the boot and other disks to two or more redundant storage devices. A node continues to function after storage device failure provided one device remains available. Mirroring does not support replacement of a failed disk. Reprovision the node to restore the mirror to a pristine, non-degraded state. Note For user-provisioned infrastructure deployments, mirroring is available only on RHCOS systems. Support for mirroring is available on x86_64 nodes booted with BIOS or UEFI and on ppc64le nodes. 1.4.3. Configuring disk encryption and mirroring You can enable and configure encryption and mirroring during an OpenShift Container Platform installation. Prerequisites You have downloaded the OpenShift Container Platform installation program on your installation node. You installed Butane on your installation node. Note Butane is a command-line utility that OpenShift Container Platform uses to offer convenient, short-hand syntax for writing and validating machine configs. For more information, see "Creating machine configs with Butane". You have access to a Red Hat Enterprise Linux (RHEL) 8 machine that can be used to generate a thumbprint of the Tang exchange key. Procedure If you want to use TPM v2 to encrypt your cluster, check to see if TPM v2 encryption needs to be enabled in the host firmware for each node. This is required on most Dell systems. Check the manual for your specific system. If you want to use Tang to encrypt your cluster, follow these preparatory steps: Set up a Tang server or access an existing one. See Network-bound disk encryption for instructions. Install the clevis package on a RHEL 8 machine, if it is not already installed: USD sudo yum install clevis On the RHEL 8 machine, run the following command to generate a thumbprint of the exchange key. Replace http://tang.example.com:7500 with the URL of your Tang server: USD clevis-encrypt-tang '{"url":"http://tang.example.com:7500"}' < /dev/null > /dev/null 1 1 In this example, tangd.socket is listening on port 7500 on the Tang server. Note The clevis-encrypt-tang command generates a thumbprint of the exchange key. No data passes to the encryption command during this step; /dev/null exists here as an input instead of plain text. The encrypted output is also sent to /dev/null , because it is not required for this procedure. Example output The advertisement contains the following signing keys: PLjNyRdGw03zlRoGjQYMahSZGu9 1 1 The thumbprint of the exchange key. When the Do you wish to trust these keys? [ynYN] prompt displays, type Y . Note RHEL 8 provides Clevis version 15, which uses the SHA-1 hash algorithm to generate thumbprints. Some other distributions provide Clevis version 17 or later, which use the SHA-256 hash algorithm for thumbprints. You must use a Clevis version that uses SHA-1 to create the thumbprint, to prevent Clevis binding issues when you install Red Hat Enterprise Linux CoreOS (RHCOS) on your OpenShift Container Platform cluster nodes. If the nodes are configured with static IP addressing, run coreos-installer iso customize --dest-karg-append or use the coreos-installer --append-karg option when installing RHCOS nodes to set the IP address of the installed system. Append the ip= and other arguments needed for your network. Important Some methods for configuring static IPs do not affect the initramfs after the first boot and will not work with Tang encryption. These include the coreos-installer --copy-network option, the coreos-installer iso customize --network-keyfile option, and the coreos-installer pxe customize --network-keyfile option, as well as adding ip= arguments to the kernel command line of the live ISO or PXE image during installation. Incorrect static IP configuration causes the second boot of the node to fail. On your installation node, change to the directory that contains the installation program and generate the Kubernetes manifests for the cluster: USD ./openshift-install create manifests --dir <installation_directory> 1 1 Replace <installation_directory> with the path to the directory that you want to store the installation files in. Create a Butane config that configures disk encryption, mirroring, or both. For example, to configure storage for compute nodes, create a USDHOME/clusterconfig/worker-storage.bu file. Butane config example for a boot device variant: openshift version: 4.12.0 metadata: name: worker-storage 1 labels: machineconfiguration.openshift.io/role: worker 2 boot_device: layout: x86_64 3 luks: 4 tpm2: true 5 tang: 6 - url: http://tang.example.com:7500 7 thumbprint: PLjNyRdGw03zlRoGjQYMahSZGu9 8 threshold: 1 9 mirror: 10 devices: 11 - /dev/sda - /dev/sdb openshift: fips: true 12 1 2 For control plane configurations, replace worker with master in both of these locations. 3 Set this field to the instruction set architecture of the cluster nodes. Some examples include, x86_64 , aarch64 , or ppc64le . 4 Include this section if you want to encrypt the root file system. For more details, see "About disk encryption". 5 Include this field if you want to use a Trusted Platform Module (TPM) to encrypt the root file system. 6 Include this section if you want to use one or more Tang servers. 7 Specify the URL of a Tang server. In this example, tangd.socket is listening on port 7500 on the Tang server. 8 Specify the exchange key thumbprint, which was generated in a preceding step. 9 Specify the minimum number of TPM v2 and Tang encryption conditions that must be met for decryption to occur. The default value is 1 . For more information about this topic, see "Configuring an encryption threshold". 10 Include this section if you want to mirror the boot disk. For more details, see "About disk mirroring". 11 List all disk devices that should be included in the boot disk mirror, including the disk that RHCOS will be installed onto. 12 Include this directive to enable FIPS mode on your cluster. Important To enable FIPS mode for your cluster, you must run the installation program from a Red Hat Enterprise Linux (RHEL) computer configured to operate in FIPS mode. For more information about configuring FIPS mode on RHEL, see Installing the system in FIPS mode . If you are configuring nodes to use both disk encryption and mirroring, both features must be configured in the same Butane configuration file. If you are configuring disk encryption on a node with FIPS mode enabled, you must include the fips directive in the same Butane configuration file, even if FIPS mode is also enabled in a separate manifest. Create a control plane or compute node manifest from the corresponding Butane configuration file and save it to the <installation_directory>/openshift directory. For example, to create a manifest for the compute nodes, run the following command: USD butane USDHOME/clusterconfig/worker-storage.bu -o <installation_directory>/openshift/99-worker-storage.yaml Repeat this step for each node type that requires disk encryption or mirroring. Save the Butane configuration file in case you need to update the manifests in the future. Continue with the remainder of the OpenShift Container Platform installation. Tip You can monitor the console log on the RHCOS nodes during installation for error messages relating to disk encryption or mirroring. Important If you configure additional data partitions, they will not be encrypted unless encryption is explicitly requested. Verification After installing OpenShift Container Platform, you can verify if boot disk encryption or mirroring is enabled on the cluster nodes. From the installation host, access a cluster node by using a debug pod: Start a debug pod for the node, for example: USD oc debug node/compute-1 Set /host as the root directory within the debug shell. The debug pod mounts the root file system of the node in /host within the pod. By changing the root directory to /host , you can run binaries contained in the executable paths on the node: # chroot /host Note OpenShift Container Platform cluster nodes running Red Hat Enterprise Linux CoreOS (RHCOS) are immutable and rely on Operators to apply cluster changes. Accessing cluster nodes using SSH is not recommended. However, if the OpenShift Container Platform API is not available, or kubelet is not properly functioning on the target node, oc operations will be impacted. In such situations, it is possible to access nodes using ssh core@<node>.<cluster_name>.<base_domain> instead. If you configured boot disk encryption, verify if it is enabled: From the debug shell, review the status of the root mapping on the node: # cryptsetup status root Example output /dev/mapper/root is active and is in use. type: LUKS2 1 cipher: aes-xts-plain64 2 keysize: 512 bits key location: keyring device: /dev/sda4 3 sector size: 512 offset: 32768 sectors size: 15683456 sectors mode: read/write 1 The encryption format. When the TPM v2 or Tang encryption modes are enabled, the RHCOS boot disks are encrypted using the LUKS2 format. 2 The encryption algorithm used to encrypt the LUKS2 volume. The aes-cbc-essiv:sha256 cipher is used if FIPS mode is enabled. 3 The device that contains the encrypted LUKS2 volume. If mirroring is enabled, the value will represent a software mirror device, for example /dev/md126 . List the Clevis plugins that are bound to the encrypted device: # clevis luks list -d /dev/sda4 1 1 Specify the device that is listed in the device field in the output of the preceding step. Example output 1: sss '{"t":1,"pins":{"tang":[{"url":"http://tang.example.com:7500"}]}}' 1 1 In the example output, the Tang plugin is used by the Shamir's Secret Sharing (SSS) Clevis plugin for the /dev/sda4 device. If you configured mirroring, verify if it is enabled: From the debug shell, list the software RAID devices on the node: # cat /proc/mdstat Example output Personalities : [raid1] md126 : active raid1 sdb3[1] sda3[0] 1 393152 blocks super 1.0 [2/2] [UU] md127 : active raid1 sda4[0] sdb4[1] 2 51869632 blocks super 1.2 [2/2] [UU] unused devices: <none> 1 The /dev/md126 software RAID mirror device uses the /dev/sda3 and /dev/sdb3 disk devices on the cluster node. 2 The /dev/md127 software RAID mirror device uses the /dev/sda4 and /dev/sdb4 disk devices on the cluster node. Review the details of each of the software RAID devices listed in the output of the preceding command. The following example lists the details of the /dev/md126 device: # mdadm --detail /dev/md126 Example output /dev/md126: Version : 1.0 Creation Time : Wed Jul 7 11:07:36 2021 Raid Level : raid1 1 Array Size : 393152 (383.94 MiB 402.59 MB) Used Dev Size : 393152 (383.94 MiB 402.59 MB) Raid Devices : 2 Total Devices : 2 Persistence : Superblock is persistent Update Time : Wed Jul 7 11:18:24 2021 State : clean 2 Active Devices : 2 3 Working Devices : 2 4 Failed Devices : 0 5 Spare Devices : 0 Consistency Policy : resync Name : any:md-boot 6 UUID : ccfa3801:c520e0b5:2bee2755:69043055 Events : 19 Number Major Minor RaidDevice State 0 252 3 0 active sync /dev/sda3 7 1 252 19 1 active sync /dev/sdb3 8 1 Specifies the RAID level of the device. raid1 indicates RAID 1 disk mirroring. 2 Specifies the state of the RAID device. 3 4 States the number of underlying disk devices that are active and working. 5 States the number of underlying disk devices that are in a failed state. 6 The name of the software RAID device. 7 8 Provides information about the underlying disk devices used by the software RAID device. List the file systems mounted on the software RAID devices: # mount | grep /dev/md Example output /dev/md127 on / type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,prjquota) /dev/md127 on /etc type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,prjquota) /dev/md127 on /usr type xfs (ro,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,prjquota) /dev/md127 on /sysroot type xfs (ro,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,prjquota) /dev/md127 on /var type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,prjquota) /dev/md127 on /var/lib/containers/storage/overlay type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,prjquota) /dev/md127 on /var/lib/kubelet/pods/e5054ed5-f882-4d14-b599-99c050d4e0c0/volume-subpaths/etc/tuned/1 type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,prjquota) /dev/md127 on /var/lib/kubelet/pods/e5054ed5-f882-4d14-b599-99c050d4e0c0/volume-subpaths/etc/tuned/2 type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,prjquota) /dev/md127 on /var/lib/kubelet/pods/e5054ed5-f882-4d14-b599-99c050d4e0c0/volume-subpaths/etc/tuned/3 type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,prjquota) /dev/md127 on /var/lib/kubelet/pods/e5054ed5-f882-4d14-b599-99c050d4e0c0/volume-subpaths/etc/tuned/4 type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,prjquota) /dev/md127 on /var/lib/kubelet/pods/e5054ed5-f882-4d14-b599-99c050d4e0c0/volume-subpaths/etc/tuned/5 type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,prjquota) /dev/md126 on /boot type ext4 (rw,relatime,seclabel) In the example output, the /boot file system is mounted on the /dev/md126 software RAID device and the root file system is mounted on /dev/md127 . Repeat the verification steps for each OpenShift Container Platform node type. Additional resources For more information about the TPM v2 and Tang encryption modes, see Configuring automated unlocking of encrypted volumes using policy-based decryption . 1.4.4. Configuring a RAID-enabled data volume You can enable software RAID partitioning to provide an external data volume. OpenShift Container Platform supports RAID 0, RAID 1, RAID 4, RAID 5, RAID 6, and RAID 10 for data protection and fault tolerance. See "About disk mirroring" for more details. Prerequisites You have downloaded the OpenShift Container Platform installation program on your installation node. You have installed Butane on your installation node. Note Butane is a command-line utility that OpenShift Container Platform uses to provide convenient, short-hand syntax for writing machine configs, as well as for performing additional validation of machine configs. For more information, see the Creating machine configs with Butane section. Procedure Create a Butane config that configures a data volume by using software RAID. To configure a data volume with RAID 1 on the same disks that are used for a mirrored boot disk, create a USDHOME/clusterconfig/raid1-storage.bu file, for example: RAID 1 on mirrored boot disk variant: openshift version: 4.12.0 metadata: name: raid1-storage labels: machineconfiguration.openshift.io/role: worker boot_device: mirror: devices: - /dev/sda - /dev/sdb storage: disks: - device: /dev/sda partitions: - label: root-1 size_mib: 25000 1 - label: var-1 - device: /dev/sdb partitions: - label: root-2 size_mib: 25000 2 - label: var-2 raid: - name: md-var level: raid1 devices: - /dev/disk/by-partlabel/var-1 - /dev/disk/by-partlabel/var-2 filesystems: - device: /dev/md/md-var path: /var format: xfs wipe_filesystem: true with_mount_unit: true 1 2 When adding a data partition to the boot disk, a minimum value of 25000 mebibytes is recommended. If no value is specified, or if the specified value is smaller than the recommended minimum, the resulting root file system will be too small, and future reinstalls of RHCOS might overwrite the beginning of the data partition. To configure a data volume with RAID 1 on secondary disks, create a USDHOME/clusterconfig/raid1-alt-storage.bu file, for example: RAID 1 on secondary disks variant: openshift version: 4.12.0 metadata: name: raid1-alt-storage labels: machineconfiguration.openshift.io/role: worker storage: disks: - device: /dev/sdc wipe_table: true partitions: - label: data-1 - device: /dev/sdd wipe_table: true partitions: - label: data-2 raid: - name: md-var-lib-containers level: raid1 devices: - /dev/disk/by-partlabel/data-1 - /dev/disk/by-partlabel/data-2 filesystems: - device: /dev/md/md-var-lib-containers path: /var/lib/containers format: xfs wipe_filesystem: true with_mount_unit: true Create a RAID manifest from the Butane config you created in the step and save it to the <installation_directory>/openshift directory. For example, to create a manifest for the compute nodes, run the following command: USD butane USDHOME/clusterconfig/<butane_config>.bu -o <installation_directory>/openshift/<manifest_name>.yaml 1 1 Replace <butane_config> and <manifest_name> with the file names from the step. For example, raid1-alt-storage.bu and raid1-alt-storage.yaml for secondary disks. Save the Butane config in case you need to update the manifest in the future. Continue with the remainder of the OpenShift Container Platform installation. 1.5. 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 Create a Butane config including the contents of the chrony.conf file. For example, to configure chrony on worker nodes, create a 99-worker-chrony.bu file. Note See "Creating machine configs with Butane" for information about Butane. variant: openshift version: 4.12.0 metadata: name: 99-worker-chrony 1 labels: machineconfiguration.openshift.io/role: worker 2 storage: files: - path: /etc/chrony.conf mode: 0644 3 overwrite: true contents: inline: | pool 0.rhel.pool.ntp.org iburst 4 driftfile /var/lib/chrony/drift makestep 1.0 3 rtcsync logdir /var/log/chrony 1 2 On control plane nodes, substitute master for worker in both of these locations. 3 Specify an octal value mode for the mode field in the machine config file. After creating the file and applying the changes, the mode is converted to a decimal value. You can check the YAML file with the command oc get mc <mc-name> -o yaml . 4 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 . Use Butane to generate a MachineConfig object file, 99-worker-chrony.yaml , containing the configuration to be delivered to the nodes: USD butane 99-worker-chrony.bu -o 99-worker-chrony.yaml Apply the configurations in one of two ways: If the cluster is not running yet, after you generate manifest files, add the MachineConfig object file to the <installation_directory>/openshift directory, and then continue to create the cluster. If the cluster is already running, apply the file: USD oc apply -f ./99-worker-chrony.yaml 1.6. Additional resources For information on Butane, see Creating machine configs with Butane . For information on FIPS support, see Support for FIPS cryptography .

Commands:
curl https://mirror.openshift.com/pub/openshift-v4/clients/butane/latest/butane --output butane
curl https://mirror.openshift.com/pub/openshift-v4/clients/butane/latest/butane-aarch64 --output butane
chmod +x butane
echo USDPATH
butane <butane_file>
variant: openshift version: 4.12.0 metadata: name: 99-worker-custom labels: machineconfiguration.openshift.io/role: worker openshift: kernel_arguments: - loglevel=7 storage: files: - path: /etc/chrony.conf mode: 0644 overwrite: true contents: inline: | pool 0.rhel.pool.ntp.org iburst driftfile /var/lib/chrony/drift makestep 1.0 3 rtcsync logdir /var/log/chrony
butane 99-worker-custom.bu -o ./99-worker-custom.yaml
oc create -f 99-worker-custom.yaml
./openshift-install create manifests --dir <installation_directory>
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
subscription-manager register
subscription-manager attach --auto
yum install podman make git -y
mkdir kmods; cd kmods
git clone https://github.com/kmods-via-containers/kmods-via-containers
cd kmods-via-containers/
sudo make install
sudo systemctl daemon-reload
cd .. ; git clone https://github.com/kmods-via-containers/kvc-simple-kmod
cd kvc-simple-kmod
cat simple-kmod.conf
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"
sudo make install
sudo kmods-via-containers build simple-kmod USD(uname -r)
sudo systemctl enable kmods-via-containers@simple-kmod.service --now
sudo systemctl status kmods-via-containers@simple-kmod.service
● 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
lsmod | grep simple_
simple_procfs_kmod 16384 0 simple_kmod 16384 0
dmesg | grep 'Hello world'
[ 6420.761332] Hello world from simple_kmod.
sudo cat /proc/simple-procfs-kmod
simple-procfs-kmod number = 0
sudo spkut 44
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
subscription-manager register
subscription-manager attach --auto
yum install podman make git -y
mkdir kmods; cd kmods
git clone https://github.com/kmods-via-containers/kmods-via-containers
git clone https://github.com/kmods-via-containers/kvc-simple-kmod
FAKEROOT=USD(mktemp -d)
cd kmods-via-containers
make install DESTDIR=USD{FAKEROOT}/usr/local CONFDIR=USD{FAKEROOT}/etc/
cd ../kvc-simple-kmod
make install DESTDIR=USD{FAKEROOT}/usr/local CONFDIR=USD{FAKEROOT}/etc/
cd .. && rm -rf kmod-tree && cp -Lpr USD{FAKEROOT} kmod-tree
variant: openshift version: 4.12.0 metadata: name: 99-simple-kmod labels: machineconfiguration.openshift.io/role: worker 1 storage: trees: - local: kmod-tree systemd: units: - name: kmods-via-containers@simple-kmod.service enabled: true
butane 99-simple-kmod.bu --files-dir . -o 99-simple-kmod.yaml
oc create -f 99-simple-kmod.yaml
lsmod | grep simple_
simple_procfs_kmod 16384 0 simple_kmod 16384 0
variant: openshift version: 4.12.0 metadata: name: worker-storage labels: machineconfiguration.openshift.io/role: worker boot_device: layout: x86_64 1 luks: tpm2: true 2 tang: 3 - url: http://tang1.example.com:7500 thumbprint: jwGN5tRFK-kF6pIX89ssF3khxxX - url: http://tang2.example.com:7500 thumbprint: VCJsvZFjBSIHSldw78rOrq7h2ZF threshold: 2 4 openshift: fips: true
sudo yum install clevis
clevis-encrypt-tang '{"url":"http://tang.example.com:7500"}' < /dev/null > /dev/null 1
The advertisement contains the following signing keys: PLjNyRdGw03zlRoGjQYMahSZGu9 1
./openshift-install create manifests --dir <installation_directory> 1
variant: openshift version: 4.12.0 metadata: name: worker-storage 1 labels: machineconfiguration.openshift.io/role: worker 2 boot_device: layout: x86_64 3 luks: 4 tpm2: true 5 tang: 6 - url: http://tang.example.com:7500 7 thumbprint: PLjNyRdGw03zlRoGjQYMahSZGu9 8 threshold: 1 9 mirror: 10 devices: 11 - /dev/sda - /dev/sdb openshift: fips: true 12
butane USDHOME/clusterconfig/worker-storage.bu -o <installation_directory>/openshift/99-worker-storage.yaml
oc debug node/compute-1
chroot /host
cryptsetup status root
/dev/mapper/root is active and is in use. type: LUKS2 1 cipher: aes-xts-plain64 2 keysize: 512 bits key location: keyring device: /dev/sda4 3 sector size: 512 offset: 32768 sectors size: 15683456 sectors mode: read/write
clevis luks list -d /dev/sda4 1
1: sss '{"t":1,"pins":{"tang":[{"url":"http://tang.example.com:7500"}]}}' 1
cat /proc/mdstat
Personalities : [raid1] md126 : active raid1 sdb3[1] sda3[0] 1 393152 blocks super 1.0 [2/2] [UU] md127 : active raid1 sda4[0] sdb4[1] 2 51869632 blocks super 1.2 [2/2] [UU] unused devices: <none>
mdadm --detail /dev/md126
/dev/md126: Version : 1.0 Creation Time : Wed Jul 7 11:07:36 2021 Raid Level : raid1 1 Array Size : 393152 (383.94 MiB 402.59 MB) Used Dev Size : 393152 (383.94 MiB 402.59 MB) Raid Devices : 2 Total Devices : 2 Persistence : Superblock is persistent Update Time : Wed Jul 7 11:18:24 2021 State : clean 2 Active Devices : 2 3 Working Devices : 2 4 Failed Devices : 0 5 Spare Devices : 0 Consistency Policy : resync Name : any:md-boot 6 UUID : ccfa3801:c520e0b5:2bee2755:69043055 Events : 19 Number Major Minor RaidDevice State 0 252 3 0 active sync /dev/sda3 7 1 252 19 1 active sync /dev/sdb3 8
mount | grep /dev/md
/dev/md127 on / type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,prjquota) /dev/md127 on /etc type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,prjquota) /dev/md127 on /usr type xfs (ro,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,prjquota) /dev/md127 on /sysroot type xfs (ro,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,prjquota) /dev/md127 on /var type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,prjquota) /dev/md127 on /var/lib/containers/storage/overlay type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,prjquota) /dev/md127 on /var/lib/kubelet/pods/e5054ed5-f882-4d14-b599-99c050d4e0c0/volume-subpaths/etc/tuned/1 type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,prjquota) /dev/md127 on /var/lib/kubelet/pods/e5054ed5-f882-4d14-b599-99c050d4e0c0/volume-subpaths/etc/tuned/2 type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,prjquota) /dev/md127 on /var/lib/kubelet/pods/e5054ed5-f882-4d14-b599-99c050d4e0c0/volume-subpaths/etc/tuned/3 type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,prjquota) /dev/md127 on /var/lib/kubelet/pods/e5054ed5-f882-4d14-b599-99c050d4e0c0/volume-subpaths/etc/tuned/4 type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,prjquota) /dev/md127 on /var/lib/kubelet/pods/e5054ed5-f882-4d14-b599-99c050d4e0c0/volume-subpaths/etc/tuned/5 type xfs (rw,relatime,seclabel,attr2,inode64,logbufs=8,logbsize=32k,prjquota) /dev/md126 on /boot type ext4 (rw,relatime,seclabel)
variant: openshift version: 4.12.0 metadata: name: raid1-storage labels: machineconfiguration.openshift.io/role: worker boot_device: mirror: devices: - /dev/sda - /dev/sdb storage: disks: - device: /dev/sda partitions: - label: root-1 size_mib: 25000 1 - label: var-1 - device: /dev/sdb partitions: - label: root-2 size_mib: 25000 2 - label: var-2 raid: - name: md-var level: raid1 devices: - /dev/disk/by-partlabel/var-1 - /dev/disk/by-partlabel/var-2 filesystems: - device: /dev/md/md-var path: /var format: xfs wipe_filesystem: true with_mount_unit: true
variant: openshift version: 4.12.0 metadata: name: raid1-alt-storage labels: machineconfiguration.openshift.io/role: worker storage: disks: - device: /dev/sdc wipe_table: true partitions: - label: data-1 - device: /dev/sdd wipe_table: true partitions: - label: data-2 raid: - name: md-var-lib-containers level: raid1 devices: - /dev/disk/by-partlabel/data-1 - /dev/disk/by-partlabel/data-2 filesystems: - device: /dev/md/md-var-lib-containers path: /var/lib/containers format: xfs wipe_filesystem: true with_mount_unit: true
butane USDHOME/clusterconfig/<butane_config>.bu -o <installation_directory>/openshift/<manifest_name>.yaml 1
variant: openshift version: 4.12.0 metadata: name: 99-worker-chrony 1 labels: machineconfiguration.openshift.io/role: worker 2 storage: files: - path: /etc/chrony.conf mode: 0644 3 overwrite: true contents: inline: | pool 0.rhel.pool.ntp.org iburst 4 driftfile /var/lib/chrony/drift makestep 1.0 3 rtcsync logdir /var/log/chrony
butane 99-worker-chrony.bu -o 99-worker-chrony.yaml
oc apply -f ./99-worker-chrony.yaml