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Use zero touch provisioning (ZTP) to provision distributed units at new edge sites in a disconnected environment. The workflow starts when the site is connected to the network and ends with the CNF workload deployed and running on the site nodes.

ZTP for RAN deployments is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.

For more information about the support scope of Red Hat Technology Preview features, see https://access.redhat.com/support/offerings/techpreview/.

Provisioning edge sites at scale

Telco edge computing presents extraordinary challenges with managing hundreds to tens of thousands of clusters in hundreds of thousands of locations. These challenges require fully-automated management solutions with, as closely as possible, zero human interaction.

Zero touch provisioning (ZTP) allows you to provision new edge sites with declarative configurations of bare-metal equipment at remote sites. Template or overlay configurations install OpenShift Container Platform features that are required for CNF workloads. End-to-end functional test suites are used to verify CNF related features. All configurations are declarative in nature.

You start the workflow by creating declarative configurations for ISO images that are delivered to the edge nodes to begin the installation process. The images are used to repeatedly provision large numbers of nodes efficiently and quickly, allowing you keep up with requirements from the field for far edge nodes.

Service providers are deploying a more distributed mobile network architecture allowed by the modular functional framework defined for 5G. This allows service providers to move from appliance-based radio access networks (RAN) to open cloud RAN architecture, gaining flexibility and agility in delivering services to end users.

The following diagram shows how ZTP works within a far edge framework.

ZTP in a far edge framework

The GitOps approach

ZTP uses the GitOps deployment set of practices for infrastructure deployment that allows developers to perform tasks that would otherwise fall under the purview of IT operations. GitOps achieves these tasks using declarative specifications stored in Git repositories, such as YAML files and other defined patterns, that provide a framework for deploying the infrastructure. The declarative output is leveraged by the Open Cluster Manager (OCM) for multisite deployment.

One of the motivators for a GitOps approach is the requirement for reliability at scale. This is a significant challenge that GitOps helps solve.

GitOps addresses the reliability issue by providing traceability, RBAC, and a single source of truth for the desired state of each site. Scale issues are addressed by GitOps providing structure, tooling, and event driven operations through webhooks.

About ZTP and distributed units on single nodes

You can install a distributed unit (DU) on a single node at scale with Red Hat Advanced Cluster Management (RHACM) (ACM) using the assisted installer (AI) and the policy generator with core-reduction technology enabled. The DU installation is done using zero touch provisioning (ZTP) in a disconnected environment.

ACM manages clusters in a hub and spoke architecture, where a single hub cluster manages many spoke clusters. ACM applies radio access network (RAN) policies from predefined custom resources (CRs). Hub clusters running ACM provision and deploy the spoke clusters using ZTP and AI. DU installation follows the AI installation of OpenShift Container Platform on a single node.

The AI service handles provisioning of OpenShift Container Platform on single nodes running on bare metal. ACM ships with and deploys the assisted installer when the MultiClusterHub custom resource is installed.

With ZTP and AI, you can provision OpenShift Container Platform single nodes to run your DUs at scale. A high level overview of ZTP for distributed units in a disconnected environment is as follows:

  • A hub cluster running ACM manages a disconnected internal registry that mirrors the OpenShift Container Platform release images. The internal registry is used to provision the spoke single nodes.

  • You manage the bare metal host machines for your DUs in an inventory file that uses YAML for formatting. You store the inventory file in a Git repository.

  • You install the DU bare metal host machines on site, and make the hosts ready for provisioning. To be ready for provisioning, the following is required for each bare metal host:

    • Network connectivity - including DNS for your network. Hosts should be reachable through the hub and managed spoke clusters. Ensure there is layer 3 connectivity between the hub and the host where you want to install your hub cluster.

    • Baseboard Management Controller (BMC) details for each host - ZTP uses BMC details to connect the URL and credentials for accessing the BMC. Create spoke cluster definition CRs. These define the relevant elements for the managed clusters. Required CRs are as follows:

      Custom Resource Description

      Namespace

      Namespace for the managed single node cluster.

      BMCSecret CR

      Credentials for the host BMC.

      Image Pull Secret CR

      Pull secret for the disconnected registry.

      AgentClusterInstall

      Specifies the single node cluster’s configuration such as networking, number of supervisor (control plane) nodes, and so on.

      ClusterDeployment

      Defines the cluster name, domain, and other details.

      KlusterletAddonConfig

      Manages installation and termination of add-ons on the ManagedCluster for ACM.

      ManagedCluster

      Describes the managed cluster for ACM.

      InfraEnv

      Describes the installation ISO to be mounted on the destination node that the assisted installer service creates. This is the final step of the manifest creation phase.

      BareMetalHost

      Describes the details of the bare metal host, including BMC and credentials details.

  • When a change is detected in the host inventory repository, a host management event is triggered to provision the new or updated host.

  • The host is provisioned. When the host is provisioned and successfully rebooted, the host agent reports Ready status to the hub cluster.

Zero touch provisioning building blocks

ACM deploys single node OpenShift (SNO), which is OpenShift Container Platform installed on single nodes, leveraging zero touch provisioning (ZTP). The initial site plan is broken down into smaller components and initial configuration data is stored in a Git repository. Zero touch provisioning uses a declarative GitOps approach to deploy these nodes. The deployment of the nodes includes:

  • Installing the host operating system (RHCOS) on a blank server.

  • Deploying OpenShift Container Platform on single nodes.

  • Creating cluster policies and site subscriptions.

  • Leveraging a GitOps deployment topology for a develop once, deploy anywhere model.

  • Making the necessary network configurations to the server operating system.

  • Deploying profile Operators and performing any needed software-related configuration, such as performance profile, PTP, and SR-IOV.

  • Downloading images needed to run workloads (CNFs).

Single node clusters

You use zero touch provisioning (ZTP) to deploy single node clusters to run distributed units (DUs) on small hardware footprints at disconnected far edge sites. A single node cluster runs OpenShift Container Platform on top of one bare metal machine, hence the single node. Edge servers contain a single node with supervisor functions and worker functions on the same host that are deployed at low bandwidth or disconnected edge sites.

OpenShift Container Platform is configured on the single node to use workload partitioning. Workload partitioning separates cluster management workloads from user workloads and can run the cluster management workloads on a reserved set of CPUs. Workload partitioning is useful for resource-constrained environments, such as single-node production deployments, where you want to reserve most of the CPU resources for user workloads and configure OpenShift Container Platform to use fewer CPU resources within the host.

A single node cluster hosting a DU application on a node is divided into the following configuration categories:

  • Common - Values are the same for all single node cluster sites managed by a hub cluster.

  • Pools of sites - Common across a pool of sites where a pool size can be 1 to n.

  • Site specific - Likely specific to a site with no overlap with other sites, for example, a vlan.

Site planning considerations for distributed unit deployments

Site planning for distributed units (DU) deployments is complex. The following is an overview of the tasks that you complete before the DU hosts are brought online in the production environment.

  • Develop a network model. The network model depends on various factors such as the size of the area of coverage, number of hosts, projected traffic load, DNS, and DHCP requirements.

  • Decide how many DU radio nodes are required to provide sufficient coverage and redundancy for your network.

  • Develop mechanical and electrical specifications for the DU host hardware.

  • Develop a construction plan for individual DU site installations.

  • Tune host BIOS settings for production, and deploy the BIOS configuration to the hosts.

  • Install the equipment on-site, connect hosts to the network, and apply power.

  • Configure on-site switches and routers.

  • Perform basic connectivity tests for the host machines.

  • Establish production network connectivity, and verify host connections to the network.

  • Provision and deploy on-site DU hosts at scale.

  • Test and verify on-site operations, performing load and scale testing of the DU hosts before finally bringing the DU infrastructure online in the live production environment.

Low latency for distributed units (DUs)

Low latency is an integral part of the development of 5G networks. Telecommunications networks require as little signal delay as possible to ensure quality of service in a variety of critical use cases.

Low latency processing is essential for any communication with timing constraints that affect functionality and security. For example, 5G Telco applications require a guaranteed one millisecond one-way latency to meet Internet of Things (IoT) requirements. Low latency is also critical for the future development of autonomous vehicles, smart factories, and online gaming. Networks in these environments require almost a real-time flow of data.

Low latency systems are about guarantees with regards to response and processing times. This includes keeping a communication protocol running smoothly, ensuring device security with fast responses to error conditions, or just making sure a system is not lagging behind when receiving a lot of data. Low latency is key for optimal synchronization of radio transmissions.

OpenShift Container Platform enables low latency processing for DUs running on COTS hardware by using a number of technologies and specialized hardware devices:

Real-time kernel for RHCOS

Ensures workloads are handled with a high degree of process determinism.

CPU isolation

Avoids CPU scheduling delays and ensures CPU capacity is available consistently.

NUMA awareness

Aligns memory and huge pages with CPU and PCI devices to pin guaranteed container memory and huge pages to the NUMA node. This decreases latency and improves performance of the node.

Huge pages memory management

Using huge page sizes improves system performance by reducing the amount of system resources required to access page tables.

Precision timing synchronization using PTP

Allows synchronization between nodes in the network with sub-microsecond accuracy.

Configuring BIOS for distributed unit bare-metal hosts

Distributed unit (DU) hosts require the BIOS to be configured before the host can be provisioned. The BIOS configuration is dependent on the specific hardware that runs your DUs and the particular requirements of your installation.

In this Developer Preview release, configuration and tuning of BIOS for DU bare-metal host machines is the responsibility of the customer. Automatic setting of BIOS is not handled by the zero touch provisioning workflow.

Procedure
  1. Set the UEFI/BIOS Boot Mode to UEFI.

  2. In the host boot sequence order, set Hard drive first.

  3. Apply the specific BIOS configuration for your hardware. The following table describes a representative BIOS configuration for an Intel Xeon Skylake or Intel Cascade Lake server, based on the Intel FlexRAN 4G and 5G baseband PHY reference design.

    The exact BIOS configuration depends on your specific hardware and network requirements. The following sample configuration is for illustrative purposes only.

    Table 1. Sample BIOS configuration for an Intel Xeon Skylake or Cascade Lake server
    BIOS Setting Configuration

    CPU Power and Performance Policy

    Performance

    Uncore Frequency Scaling

    Disabled

    Performance P-limit

    Disabled

    Enhanced Intel SpeedStep ® Tech

    Enabled

    Intel Configurable TDP

    Enabled

    Configurable TDP Level

    Level 2

    Intel® Turbo Boost Technology

    Enabled

    Energy Efficient Turbo

    Disabled

    Hardware P-States

    Disabled

    Package C-State

    C0/C1 state

    C1E

    Disabled

    Processor C6

    Disabled

Enable global SR-IOV and VT-d settings in the BIOS for the host. These settings are relevant to bare-metal environments.

Preparing the disconnected environment

Before you can provision distributed units (DU) at scale, you must install Red Hat Advanced Cluster Management (RHACM), which handles the provisioning of the DUs.

RHACM is deployed as an Operator on the OpenShift Container Platform hub cluster. It controls clusters and applications from a single console with built-in security policies. RHACM provisions and manage your DU hosts. To install RHACM in a disconnected environment, you create a mirror registry that mirrors the Operator Lifecycle Manager (OLM) catalog that contains the required Operator images. OLM manages, installs, and upgrades Operators and their dependencies in the cluster.

You also use a disconnected mirror host to serve the RHCOS ISO and RootFS disk images that provision the DU bare-metal host operating system.

Before you install a cluster on infrastructure that you provision in a restricted network, you must mirror the required container images into that environment. You can also use this procedure in unrestricted networks to ensure your clusters only use container images that have satisfied your organizational controls on external content.

You must have access to the internet to obtain the necessary container images. In this procedure, you place the mirror registry on a mirror host that has access to both your network and the internet. If you do not have access to a mirror host, use the disconnected procedure to copy images to a device that you can move across network boundaries.

Disconnected environment prerequisites

You must have a container image registry that supports Docker v2-2 in the location that will host the OpenShift Container Platform cluster, such as one of the following registries:

If you have an entitlement to Red Hat Quay, see the documentation on deploying Red Hat Quay for proof-of-concept purposes or by using the Quay Operator. If you need additional assistance selecting and installing a registry, contact your sales representative or Red Hat support.

About the mirror registry

You can mirror the images that are required for OpenShift Container Platform installation and subsequent product updates to a mirror registry. These actions use the same process. The release image, which contains the description of the content, and the images it references are all mirrored. In addition, the Operator catalog source image and the images that it references must be mirrored for each Operator that you use. After you mirror the content, you configure each cluster to retrieve this content from your mirror registry.

The mirror registry can be any container registry that supports Docker v2-2. All major cloud provider registries, as well as Red Hat Quay, Artifactory, and others, have the necessary support. Using one of these registries ensures that OpenShift Container Platform can verify the integrity of each image in disconnected environments.

The internal registry of the OpenShift Container Platform cluster cannot be used as the target registry because it does not support pushing without a tag, which is required during the mirroring process.

The mirror registry must be reachable by every machine in the clusters that you provision. If the registry is unreachable installation, updating, or normal operations such as workload relocation might fail. For that reason, you must run mirror registries in a highly available way, and the mirror registries must at least match the production availability of your OpenShift Container Platform clusters.

When you populate a mirror registry with OpenShift Container Platform images, you can follow two scenarios. If you have a host that can access both the internet and your mirror registry, but not your cluster nodes, you can directly mirror the content from that machine. This process is referred to as connected mirroring. If you have no such host, you must mirror the images to a file system and then bring that host or removable media into your restricted environment. This process is referred to as disconnected mirroring.

For mirrored registries, to view the source of pulled images, you must review the Trying to access log entry in the CRI-O logs. Other methods to view the image pull source, such as using the crictl images command on a node, show the non-mirrored image name, even though the image is pulled from the mirrored location.

Additional resources

For information on viewing the CRI-O logs to view the image source, see Viewing the image pull source.

Preparing your mirror host

Before you perform the mirror procedure, you must prepare the host to retrieve content and push it to the remote location.

Installing the OpenShift CLI by downloading the binary

You can install the OpenShift CLI (oc) to interact with OpenShift Container Platform from a command-line interface. You can install oc on Linux, Windows, or macOS.

If you installed an earlier version of oc, you cannot use it to complete all of the commands in OpenShift Container Platform 4.9. Download and install the new version of oc.

Installing the OpenShift CLI on Linux

You can install the OpenShift CLI (oc) binary on Linux by using the following procedure.

Procedure
  1. Navigate to the OpenShift Container Platform downloads page on the Red Hat Customer Portal.

  2. Select the appropriate version in the Version drop-down menu.

  3. Click Download Now next to the OpenShift v4.9 Linux Client entry and save the file.

  4. Unpack the archive:

    $ tar xvzf <file>
  5. Place the oc binary in a directory that is on your PATH.

    To check your PATH, execute the following command:

    $ echo $PATH

After you install the OpenShift CLI, it is available using the oc command:

$ oc <command>
Installing the OpenShift CLI on Windows

You can install the OpenShift CLI (oc) binary on Windows by using the following procedure.

Procedure
  1. Navigate to the OpenShift Container Platform downloads page on the Red Hat Customer Portal.

  2. Select the appropriate version in the Version drop-down menu.

  3. Click Download Now next to the OpenShift v4.9 Windows Client entry and save the file.

  4. Unzip the archive with a ZIP program.

  5. Move the oc binary to a directory that is on your PATH.

    To check your PATH, open the command prompt and execute the following command:

    C:\> path

After you install the OpenShift CLI, it is available using the oc command:

C:\> oc <command>
Installing the OpenShift CLI on macOS

You can install the OpenShift CLI (oc) binary on macOS by using the following procedure.

Procedure
  1. Navigate to the OpenShift Container Platform downloads page on the Red Hat Customer Portal.

  2. Select the appropriate version in the Version drop-down menu.

  3. Click Download Now next to the OpenShift v4.9 MacOSX Client entry and save the file.

  4. Unpack and unzip the archive.

  5. Move the oc binary to a directory on your PATH.

    To check your PATH, open a terminal and execute the following command:

    $ echo $PATH

After you install the OpenShift CLI, it is available using the oc command:

$ oc <command>

Configuring credentials that allow images to be mirrored

Create a container image registry credentials file that allows mirroring images from Red Hat to your mirror.

Prerequisites
  • You configured a mirror registry to use in your restricted network.

Procedure

Complete the following steps on the installation host:

  1. Download your registry.redhat.io pull secret from the Pull Secret page on the Red Hat OpenShift Cluster Manager site and save it to a .json file.

  2. Generate the base64-encoded user name and password or token for your mirror registry:

    $ echo -n '<user_name>:<password>' | base64 -w0 (1)
    BGVtbYk3ZHAtqXs=
    1 For <user_name> and <password>, specify the user name and password that you configured for your registry.
  3. Make a copy of your pull secret in JSON format:

    $ cat ./pull-secret.text | jq .  > <path>/<pull_secret_file_in_json>(1)
    1 Specify the path to the folder to store the pull secret in and a name for the JSON file that you create.

    The contents of the file resemble the following example:

    {
      "auths": {
        "cloud.openshift.com": {
          "auth": "b3BlbnNo...",
          "email": "you@example.com"
        },
        "quay.io": {
          "auth": "b3BlbnNo...",
          "email": "you@example.com"
        },
        "registry.connect.redhat.com": {
          "auth": "NTE3Njg5Nj...",
          "email": "you@example.com"
        },
        "registry.redhat.io": {
          "auth": "NTE3Njg5Nj...",
          "email": "you@example.com"
        }
      }
    }
  4. Edit the new file and add a section that describes your registry to it:

      "auths": {
        "<mirror_registry>": { (1)
          "auth": "<credentials>", (2)
          "email": "you@example.com"
      },
    1 For <mirror_registry>, specify the registry domain name, and optionally the port, that your mirror registry uses to serve content. For example, registry.example.com or registry.example.com:5000
    2 For <credentials>, specify the base64-encoded user name and password for the mirror registry.

    The file resembles the following example:

    {
      "auths": {
        "registry.example.com": {
          "auth": "BGVtbYk3ZHAtqXs=",
          "email": "you@example.com"
        },
        "cloud.openshift.com": {
          "auth": "b3BlbnNo...",
          "email": "you@example.com"
        },
        "quay.io": {
          "auth": "b3BlbnNo...",
          "email": "you@example.com"
        },
        "registry.connect.redhat.com": {
          "auth": "NTE3Njg5Nj...",
          "email": "you@example.com"
        },
        "registry.redhat.io": {
          "auth": "NTE3Njg5Nj...",
          "email": "you@example.com"
        }
      }
    }

Mirroring the OpenShift Container Platform image repository

Mirror the OpenShift Container Platform image repository to your registry to use during cluster installation or upgrade.

Prerequisites
  • Your mirror host has access to the internet.

  • You configured a mirror registry to use in your restricted network and can access the certificate and credentials that you configured.

  • You downloaded the pull secret from the Pull Secret page on the Red Hat OpenShift Cluster Manager site and modified it to include authentication to your mirror repository.

  • If you use self-signed certificates that do not set a Subject Alternative Name, you must precede the oc commands in this procedure with GODEBUG=x509ignoreCN=0. If you do not set this variable, the oc commands will fail with the following error:

    x509: certificate relies on legacy Common Name field, use SANs or temporarily enable Common Name matching with GODEBUG=x509ignoreCN=0
Procedure

Complete the following steps on the mirror host:

  1. Review the OpenShift Container Platform downloads page to determine the version of OpenShift Container Platform that you want to install and determine the corresponding tag on the Repository Tags page.

  2. Set the required environment variables:

    1. Export the release version:

      $ OCP_RELEASE=<release_version>

      For <release_version>, specify the tag that corresponds to the version of OpenShift Container Platform to install, such as 4.5.4.

    2. Export the local registry name and host port:

      $ LOCAL_REGISTRY='<local_registry_host_name>:<local_registry_host_port>'

      For <local_registry_host_name>, specify the registry domain name for your mirror repository, and for <local_registry_host_port>, specify the port that it serves content on.

    3. Export the local repository name:

      $ LOCAL_REPOSITORY='<local_repository_name>'

      For <local_repository_name>, specify the name of the repository to create in your registry, such as ocp4/openshift4.

    4. Export the name of the repository to mirror:

      $ PRODUCT_REPO='openshift-release-dev'

      For a production release, you must specify openshift-release-dev.

    5. Export the path to your registry pull secret:

      $ LOCAL_SECRET_JSON='<path_to_pull_secret>'

      For <path_to_pull_secret>, specify the absolute path to and file name of the pull secret for your mirror registry that you created.

    6. Export the release mirror:

      $ RELEASE_NAME="ocp-release"

      For a production release, you must specify ocp-release.

    7. Export the type of architecture for your server, such as x86_64:

      $ ARCHITECTURE=<server_architecture>
    8. Export the path to the directory to host the mirrored images:

      $ REMOVABLE_MEDIA_PATH=<path> (1)
      1 Specify the full path, including the initial forward slash (/) character.
  3. Mirror the version images to the internal container registry:

    • If your mirror host does not have internet access, take the following actions:

      1. Connect the removable media to a system that is connected to the internet.

      2. Review the images and configuration manifests to mirror:

        $ oc adm release mirror -a ${LOCAL_SECRET_JSON}  \
             --from=quay.io/${PRODUCT_REPO}/${RELEASE_NAME}:${OCP_RELEASE}-${ARCHITECTURE} \
             --to=${LOCAL_REGISTRY}/${LOCAL_REPOSITORY} \
             --to-release-image=${LOCAL_REGISTRY}/${LOCAL_REPOSITORY}:${OCP_RELEASE}-${ARCHITECTURE} --dry-run
      3. Record the entire imageContentSources section from the output of the previous command. The information about your mirrors is unique to your mirrored repository, and you must add the imageContentSources section to the install-config.yaml file during installation.

      4. Mirror the images to a directory on the removable media:

        $ oc adm release mirror -a ${LOCAL_SECRET_JSON} --to-dir=${REMOVABLE_MEDIA_PATH}/mirror quay.io/${PRODUCT_REPO}/${RELEASE_NAME}:${OCP_RELEASE}-${ARCHITECTURE}
      5. Take the media to the restricted network environment and upload the images to the local container registry.

        $ oc image mirror -a ${LOCAL_SECRET_JSON} --from-dir=${REMOVABLE_MEDIA_PATH}/mirror "file://openshift/release:${OCP_RELEASE}*" ${LOCAL_REGISTRY}/${LOCAL_REPOSITORY} (1)
        1 For REMOVABLE_MEDIA_PATH, you must use the same path that you specified when you mirrored the images.
    • If the local container registry is connected to the mirror host, take the following actions:

      1. Directly push the release images to the local registry by using following command:

        $ oc adm release mirror -a ${LOCAL_SECRET_JSON}  \
             --from=quay.io/${PRODUCT_REPO}/${RELEASE_NAME}:${OCP_RELEASE}-${ARCHITECTURE} \
             --to=${LOCAL_REGISTRY}/${LOCAL_REPOSITORY} \
             --to-release-image=${LOCAL_REGISTRY}/${LOCAL_REPOSITORY}:${OCP_RELEASE}-${ARCHITECTURE}

        This command pulls the release information as a digest, and its output includes the imageContentSources data that you require when you install your cluster.

      2. Record the entire imageContentSources section from the output of the previous command. The information about your mirrors is unique to your mirrored repository, and you must add the imageContentSources section to the install-config.yaml file during installation.

        The image name gets patched to Quay.io during the mirroring process, and the podman images will show Quay.io in the registry on the bootstrap virtual machine.

  4. To create the installation program that is based on the content that you mirrored, extract it and pin it to the release:

    • If your mirror host does not have internet access, run the following command:

      $ oc adm release extract -a ${LOCAL_SECRET_JSON} --command=openshift-install "${LOCAL_REGISTRY}/${LOCAL_REPOSITORY}:${OCP_RELEASE}"
    • If the local container registry is connected to the mirror host, run the following command:

      $ oc adm release extract -a ${LOCAL_SECRET_JSON} --command=openshift-install "${LOCAL_REGISTRY}/${LOCAL_REPOSITORY}:${OCP_RELEASE}-${ARCHITECTURE}"

      To ensure that you use the correct images for the version of OpenShift Container Platform that you selected, you must extract the installation program from the mirrored content.

      You must perform this step on a machine with an active internet connection.

      If you are in a disconnected environment, use the --image flag as part of must-gather and point to the payload image.

  5. For clusters using installer-provisioned infrastructure, run the following command:

    $ openshift-install

Adding RHCOS ISO and RootFS images to a disconnected mirror host

Before you install a cluster on infrastructure that you provision, you must create Red Hat Enterprise Linux CoreOS (RHCOS) machines for it to use. Use a disconnected mirror to host the RHCOS images you require to provision your distributed unit (DU) bare-metal hosts.

Prerequisites
  • Deploy and configure an HTTP server to host the RHCOS image resources on the network. You must be able to access the HTTP server from your computer, and from the machines that you create.

The RHCOS images might not change with every release of OpenShift Container Platform. You must download images with the highest version that is less than or equal to the OpenShift Container Platform version that you install. Use the image versions that match your OpenShift Container Platform version if they are available. You require ISO and RootFS images to install RHCOS on the DU hosts. RHCOS qcow2 images are not supported for this installation type.

Procedure
  1. Log in to the mirror host.

  2. Obtain the RHCOS ISO and RootFS images from mirror.openshift.com, for example:

    1. Export the required image names and OpenShift Container Platform version as environment variables:

      $ export ISO_IMAGE_NAME=<iso_image_name> (1)
      $ export ROOTFS_IMAGE_NAME=<rootfs_image_name> (2)
      $ export OCP_VERSION=<ocp_version> (3)
      1 ISO image name, for example, rhcos-4.9.0-fc.1-x86_64-live.x86_64.iso
      2 RootFS image name, for example, rhcos-4.9.0-fc.1-x86_64-live-rootfs.x86_64.img
      3 OpenShift Container Platform version, for example, latest-4.9
    2. Download the required images:

      $ sudo wget https://mirror.openshift.com/pub/openshift-v4/dependencies/rhcos/pre-release/${OCP_VERSION}/${ISO_IMAGE_NAME} -O /var/www/html/${ISO_IMAGE_NAME}
      $ sudo wget https://mirror.openshift.com/pub/openshift-v4/dependencies/rhcos/pre-release/${OCP_VERSION}/${ROOTFS_IMAGE_NAME} -O /var/www/html/${ROOTFS_IMAGE_NAME}
Verification steps
  • Verify that the images downloaded successfully and are being served on the disconnected mirror host, for example:

    $ wget http://$(hostname)/${ISO_IMAGE_NAME}
    Expected output
    ...
    Saving to: rhcos-4.9.0-fc.1-x86_64-live.x86_64.iso
    rhcos-4.9.0-fc.1-x86_64-  11%[====>    ]  10.01M  4.71MB/s
    ...

Installing Red Hat Advanced Cluster Management in a disconnected environment

You use Red Hat Advanced Cluster Management (RHACM) on a hub cluster in the disconnected environment to manage the deployment of distributed unit (DU) profiles on multiple managed spoke clusters.

Prerequisites
  • Install the OpenShift Container Platform CLI (oc).

  • Log in as a user with cluster-admin privileges.

  • Configure a disconnected mirror registry for use in the cluster.

    If you want to deploy Operators to the spoke clusters, you must also add them to this registry. See Mirroring an Operator catalog for more information.

Procedure

Enabling assisted installer service on bare metal

The Assisted Installer Service (AIS) deploys OpenShift Container Platform clusters. Red Hat Advanced Cluster Management (RHACM) ships with AIS. AIS is deployed when you enable the MultiClusterHub Operator on the RHACM hub cluster.

For distributed units (DUs), RHACM supports OpenShift Container Platform deployments that run on a single bare-metal host. The single node cluster acts as both a control plane and a worker node.

Prerequisites
  • Install OpenShift Container Platform 4.9 on a hub cluster.

  • Install RHACM and create the MultiClusterHub resource.

  • Create persistent volume custom resources (CR) for database and file system storage.

  • You have installed the OpenShift CLI (oc).

Procedure
  1. Modify the HiveConfig resource to enable the feature gate for Assisted Installer:

     $ oc patch hiveconfig hive --type merge -p '{"spec":{"targetNamespace":"hive","logLevel":"debug","featureGates":{"custom":{"enabled":["AlphaAgentInstallStrategy"]},"featureSet":"Custom"}}}'
  2. Modify the Provisioning resourc