Understanding IPI in Red Hat OpenShift

techhadoop OCP

In Red Hat OpenShift Container Platform (OCP), IPI stands for Installer-Provisioned Infrastructure. It is a “full-stack automation” approach where the OpenShift installation program does literally everything for you.

Instead of you manually building virtual machines, configuring load balancers, and setting up DNS servers, you hand over API credentials to the openshift-install program, and it automatically deploys, configures, and manages the entire infrastructure stack from the ground up.

1. How IPI Works Under the Hood

The core goal of IPI is to treat your underlying infrastructure (compute, network, storage, and load balancers) as a direct software extension of the cluster itself.

Plaintext

 ┌─────────────────────────┐               API Calls               ┌─────────────────────────┐
 │   openshift-install     │ ────────────────────────────────────► │  Cloud / Virt Platform  │
 │   Command-Line Binary   │                                       │  (AWS, Azure, vSphere)  │
 └───────────┬─────────────┘                                       └────────────┬────────────┘
             │                                                                  │
             │ Provisions                                                       │ Spins up
             ▼                                                                  ▼
 ┌─────────────────────────┐                                       ┌─────────────────────────┐
 │  Bootstrap VM (Temp)    │ ────────────────────────────────────► │   Control Plane Nodes   │
 └─────────────────────────┘      First-Boot Ignition Setup        └─────────────────────────┘
  1. The Config: You define a simple configuration file called install-config.yaml specifying basic cluster details (e.g., cluster name, cloud provider, region, and target replica sizing).
  2. Infrastructure Provisioning: The installer contacts the targeted cloud provider’s API (or virtualization platform like VMware vSphere) and orchestrates the creation of resources such as VPCs, subnets, route tables, DNS entries, and virtual machines.
  3. Bootstrap Phase: It spins up a temporary Bootstrap VM to host a local Kubernetes api-server. This bootstrap node writes Red Hat Enterprise Linux CoreOS (RHCOS) system layers to the master nodes.
  4. Handoff: Once the 3 control plane nodes achieve consensus, the installer destroys the temporary Bootstrap VM automatically, leaving you with a fully operational production cluster.

2. Day-2 Automation (Why Engineers Love IPI)

The true value of IPI isn’t just the initial installation—it’s what happens after. Because the installer created the infrastructure, OpenShift retains absolute programmatic control over it.

  • Integrated MachineSets: You can scale out your worker nodes directly using OpenShift custom resources. If you update a MachineSet replica count, OpenShift natively talks to your cloud platform’s API to spin up the corresponding VM instances.
  • True Autoscaling: Cluster and machine autoscalers can scale your infrastructure dynamically based on workload demands.
  • In-Tree CSI Drivers: Storage provisioners (like AWS EBS or Azure Disk) are automatically configured for dynamic volume storage provisioning.

3. Comparing IPI vs. UPI (User-Provisioned Infrastructure)

DimensionInstaller-Provisioned (IPI)User-Provisioned (UPI)
ControlStandardized. The installer makes structural choices.Absolute control. You decide networking, firewall rules, and OS layouts.
ComplexityExtremely Low. Run one command, and wait.High. Requires manually building subnets, DNS, load balancers, and VMs.
Autoscaling NodesOut-of-the-box. Managed via MachineSets.Manual / Complex. Requires building external automated pipelines.
Cloud PermissionsNeeds high-level admin API credentials to create resources.Requires minimal permissions; you prepare the environment in advance.
Best For…Clean-slate installs, fast prototyping, and standard public clouds.Complex corporate networks, air-gapped data centers, or rigid security constraints.

4. Supported Platforms

OpenShift installer binaries support IPI across many diverse hypervisors and public clouds:

  • Public Clouds: Amazon Web Services (AWS), Microsoft Azure, Google Cloud Platform (GCP), Alibaba Cloud.
  • On-Premises / Virtualization: VMware vSphere, Red Hat OpenStack Platform, Nutanix, Bare Metal (utilizing Metal3 & Ironic automation controllers).

For a visual breakdown of how these deployment workflows compare, watch the Installing OpenShift on Bare Metal: IPI vs UPI Overview video. This tutorial explains the strategic installation differences when choosing the architecture that best fits your bare-metal or cloud infrastructure.

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