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Preparing to install with the Assisted Installer

Before installing a cluster, you must ensure the cluster nodes and network meet the requirements.

Prerequisites

Assisted Installer prerequisites

The Assisted Installer validates the following prerequisites to ensure successful installation.

Hardware

For control plane nodes or the single-node OpenShift node, nodes must have at least the following resources:

  • 8 CPU cores

  • 16.00 GiB RAM

  • 100 GB storage

  • 10ms write speed or less for etcd wal_fsync_duration_seconds

For worker nodes, each node must have at least the following resources:

  • 4 CPU cores

  • 16.00 GiB RAM

  • 100 GB storage

Networking

The network must meet the following requirements:

  • A DHCP server unless using static IP addressing.

  • A base domain name. You must ensure that the following requirements are met:

    • There is no wildcard, such as *.<cluster_name>.<base_domain>, or the installation will not proceed.

    • A DNS A/AAAA record for api.<cluster_name>.<base_domain>.

    • A DNS A/AAAA record with a wildcard for *.apps.<cluster_name>.<base_domain>.

  • Port 6443 is open for the API URL if you intend to allow users outside the firewall to access the cluster via the oc CLI tool.

  • Port 443 is open for the console if you intend to allow users outside the firewall to access the console.

DNS A/AAAA record settings at top-level domain registrars can take significant time to update. Ensure the A/AAAA record DNS settings are working before installation to prevent installation delays.

The OpenShift Container Platform cluster’s network must also meet the following requirements:

  • Connectivity between all cluster nodes

  • Connectivity for each node to the internet

  • Access to an NTP server for time synchronization between the cluster nodes

Preflight validations

The Assisted Installer ensures the cluster meets the prerequisites before installation, because it eliminates complex postinstallation troubleshooting, thereby saving significant amounts of time and effort. Before installing software on the nodes, the Assisted Installer conducts the following validations:

  • Ensures network connectivity

  • Ensures sufficient network bandwidth

  • Ensures connectivity to the registry

  • Ensures time synchronization between cluster nodes

  • Verifies that the cluster nodes meet the minimum hardware requirements

  • Validates the installation configuration parameters

If the Assisted Installer does not successfully validate the foregoing requirements, installation will not proceed.

Additional resources