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Chapter 1. About the Assisted Installer

The Assisted Installer for Red Hat OpenShift Container Platform is a user-friendly installation solution offered on the Red Hat Hybrid Cloud Console. The Assisted Installer supports various deployment platforms with a focus on bare metal, Nutanix, vSphere, and Oracle Cloud Infrastructure. The Assisted Installer also supports various CPU architectures, including x86_64, s390x (IBM Z®), arm64, and ppc64le (IBM Power®).

You can install OpenShift Container Platform on premises in a connected environment, with an optional HTTP/S proxy, for the following platforms:

  • Highly available OpenShift Container Platform or single-node OpenShift cluster
  • OpenShift Container Platform on bare metal or vSphere with full platform integration, or other virtualization platforms without integration
  • Optionally, OpenShift Virtualization and Red Hat OpenShift Data Foundation

1.1. Features

The Assisted Installer provides installation functionality as a service. This software-as-a-service (SaaS) approach has the following features:

Web interface
  • You can install your cluster by using the Hybrid Cloud Console instead of creating installation configuration files manually.
No bootstrap node
  • You do not need a bootstrap node because the bootstrapping process runs on a node within the cluster.
Streamlined installation workflow
  • You do not need in-depth knowledge of OpenShift Container Platform to deploy a cluster. The Assisted Installer provides reasonable default configurations.
  • You do not need to run the OpenShift Container Platform installer locally.
  • You have access to the latest Assisted Installer for the latest tested z-stream releases.
Advanced networking options
  • The Assisted Installer supports IPv4 and dual stack networking with OVN only, NMState-based static IP addressing, and an HTTP/S proxy.
  • OVN is the default Container Network Interface (CNI) for OpenShift Container Platform 4.12 and later.
  • SDN is supported up to OpenShift Container Platform 4.14. SDN supports IPv4 only.
Preinstallation validation

  • Before installing, the Assisted Installer checks the following configurations:

    • Network connectivity
    • Network bandwidth
    • Connectivity to the registry
    • Upstream DNS resolution of the domain name
    • Time synchronization between cluster nodes
    • Cluster node hardware
    • Installation configuration parameters
REST API
  • You can automate the installation process by using the Assisted Installer REST API.

1.2. OpenShift Container Platform host architecture: control plane and compute nodes

The OpenShift Container Platform architecture allows you to select a standard Kubernetes role for each of the discovered hosts. These roles define the function of the host within the cluster. The roles can be one of the standard Kubernetes types: control plane (master) or compute (worker).

1.2.1. About assigning roles to hosts

During the installation process, you can select a role for a host or configure the Assisted Installer to assign it for you. The options are as follows:

  • Control plane (master) node - The control plane nodes run the services that are required to control the cluster, including the API server. The control plane schedules workloads, maintains cluster state, and ensures stability. Control plane nodes are also known as master nodes.
  • Compute (worker) node - The compute nodes are responsible for executing workloads for cluster users. Compute nodes advertise their capacity, so that the control plane scheduler can identify suitable compute nodes for running pods and containers. Compute nodes are also known as worker nodes.
  • Auto-assign - This option allows the Assisted Installer to automatically select a role for each of the hosts, based on detected hardware and network latency. You can change the role at any time before installation starts.

To assign a role to a host, see either of the following sections:

1.2.2. About specifying the number of control plane nodes for your cluster

Using a higher number of control plane (master) nodes boosts fault tolerance and availability, minimizing downtime during failures. All versions of OpenShift Container Platform support one or three control plane nodes, where one control plane node is a Single-node OpenShift cluster. From OpenShift Container Platform version 4.18 and later, the Assisted Installer also supports four or five control plane nodes on a bare metal or user-managed networking platform with an x86_64 architecture. An implementation can support any number of compute nodes.

To define the required number of control plane nodes, see either of the following sections:

1.2.3. About scheduling workloads on control plane nodes

Scheduling workloads to run on control plane nodes improves efficiency and maximizes resource utilization. You can enable this option during installation setup or as a postinstallation step.

Use the following guidelines to determine when to use this feature:

  • single-node OpenShift or small clusters (up to four nodes): The system schedules workloads on control plane nodes by default. This setting cannot be changed.
  • Medium clusters (five to ten nodes): Scheduling workloads to run on control plane nodes in addition to worker nodes is the recommended configuration.
  • Large clusters (more than ten nodes): Configuring control plane nodes as schedulable is not recommended.

For instructions on configuring control plane nodes as schedulable during the installation setup, see the following sections:

For instructions on configuring schedulable control plane nodes following an installation, see Configuring control plane nodes as schedulable in the OpenShift Container Platform documentation.

Important

When you configure control plane nodes to be schedulable for workloads, an additional subscription is required for each control plane node that function as a compute (worker) node.

1.3. API support policy

Assisted Installer APIs are supported for a minimum of three months from the announcement of deprecation.

1.3.1. API deprecation notice

The following table presents the deprecated and modified APIs in the Assisted Installer.

  • assisted_service API

    Affected modelsDescription of change
    • cluster
    • cluster-create-params

    The high_availability_mode field is deprecated starting from April 2025, and is planned to be removed in three months. Red Hat will provide bug fixes and support for this feature during the current release lifecycle, but this feature will no longer receive enhancements and will be removed.

    The alternative is to use control_plane_count instead. This change enables support for clusters with 4 or 5 control plane nodes, in addition to the previously supported configurations with 1 or 3 control plane nodes. The Assisted Installer supports 4 or 5 control plane nodes starting from OpenShift Container Platform version 4.18 and later.

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