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Cluster API

cluster-api.sigs.k8s.io

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Spec score 8.8 #3 of 29 in Kubernetes Management Platforms

What it is

Cluster API is an open-source project for managing the lifecycle of multiple Kubernetes clusters through declarative APIs and tooling. Platform operators can use it to create, scale, upgrade, and destroy Kubernetes-conformant clusters across on-premises and cloud environments. Provider implementations are interchangeable; kubeadm is the default bootstrap provider. The ecosystem includes infrastructure, bootstrap, control plane, IPAM, addon, and runtime extensions, with environments such as AWS, Azure, GCP, OpenStack, vSphere, and KubeVirt. A management cluster can use clusterctl or the Cluster API Operator to manage provider components. Clusterctl fetches provider component YAML and installs it, while the Operator uses a declarative approach intended to support GitOps workflows. Getting started requires an existing Kubernetes cluster accessible through kubectl; kind, Docker, and Helm are common prerequisites. Cluster API supports multi-cluster provisioning and upgrades, but does not manage a single cluster spanning multiple infrastructure providers or clusters it did not provision. It is free and open source. The project supports its latest two minor releases, with each supported for roughly 12 months including maintenance.

Spec sheet

Purpose
Cluster API provides declarative APIs and tooling to provision, upgrade, and operate multiple Kubernetes clusters.Read 7 Oct 2026 · cluster-api.sigs.k8s.io
Intended users
The project describes its automation as intended for platform operators managing Kubernetes cluster lifecycles.Read 7 Oct 2026 · cluster-api.sigs.k8s.io
Integrations
The quick start lists infrastructure providers including AWS, Azure, GCP, OpenStack, vSphere, and KubeVirt, among others.Read 7 Oct 2026 · cluster-api.sigs.k8s.io
Security
The project’s user security guidance recommends auditing management and workload clusters, nodes, and cloud-provider activity, and using least-privilege credentials.Read 7 Oct 2026 · cluster-api.sigs.k8s.io
Bootstrap and control plane
The provider ecosystem includes bootstrap and control plane implementations, with kubeadm built in.Read 7 Oct 2026 · github.com
Community support
The project directs users to the Kubernetes Slack #cluster-api channel, the SIG Cluster Lifecycle Google Group, and weekly working-group meetings for questions and project updates.Read 7 Oct 2026 · github.com
Downloads
The clusterctl CLI has documented downloads for Linux, macOS, and Windows, plus Homebrew installation for macOS and Linux.Read 7 Oct 2026 · cluster-api.sigs.k8s.io
GitOps
The Cluster API Operator uses a declarative approach to manage providers and aims to support day-to-day workflows with GitOps.Read 7 Oct 2026 · cluster-api.sigs.k8s.io
Infrastructure
It is designed to work across on-premises and cloud environments and can be extended with infrastructure providers such as AWS, Azure, and vSphere.Read 7 Oct 2026 · cluster-api.sigs.k8s.io
Installation
The quick start offers clusterctl and the Cluster API Operator as installation paths; clusterctl fetches provider component YAML and installs it.Read 7 Oct 2026 · cluster-api.sigs.k8s.io
Lifecycle
Its stated goals include creating, scaling, upgrading, and destroying Kubernetes-conformant clusters through a declarative API.Read 7 Oct 2026 · cluster-api.sigs.k8s.io
Lifecycle operations
Its stated goals include creating, scaling, upgrading, and destroying Kubernetes-conformant clusters through a declarative API.Read 7 Oct 2026 · cluster-api.sigs.k8s.io
Management tools
The quick start describes clusterctl and the Cluster API Operator as two paths for managing provider components in a management cluster.Read 7 Oct 2026 · cluster-api.sigs.k8s.io
Notable limit
The project states that Cluster API does not manage a single cluster spanning multiple infrastructure providers or clusters that it did not provision.Read 7 Oct 2026 · cluster-api.sigs.k8s.io
Prerequisites
Using Cluster API requires an existing Kubernetes cluster accessible through kubectl; the quick start also lists kind, Docker, and Helm as common prerequisites.Read 7 Oct 2026 · cluster-api.sigs.k8s.io
Production guidance
The quick start recommends using a production management cluster with backup and disaster recovery policies and says kind is not designed for production.Read 7 Oct 2026 · cluster-api.sigs.k8s.io
Provider ecosystem
The project lists infrastructure, bootstrap, control plane, IPAM, addon, and runtime extension providers, including AWS, Azure, GCP, OpenStack, and vSphere.Read 7 Oct 2026 · cluster-api.sigs.k8s.io
Provider model
The project supports interchangeable provider implementations, with kubeadm as the default bootstrap provider.Read 7 Oct 2026 · cluster-api.sigs.k8s.io
Provider support responsibility
Each provider is maintained by its respective team, and the project recommends reviewing provider documentation and doing due diligence before production use.Read 7 Oct 2026 · cluster-api.sigs.k8s.io
Support channels
The project directs users to the Kubernetes Slack #cluster-api channel, the SIG Cluster Lifecycle Google Group, and weekly working group sessions for questions and news.Read 7 Oct 2026 · cluster-api.sigs.k8s.io
Support policy
The project actively supports its latest two minor releases, while each minor release is supported for roughly 12 months including a maintenance period.Read 7 Oct 2026 · cluster-api.sigs.k8s.io

Plans and prices

Cluster API Free Open-source Kubernetes project · provider components and infrastructure costs depend on the selected providers Read 7 Oct 2026 · github.com

Every Cluster API plan and price →

Strong points and limits

Strong points

  • Free and open source
  • Supports multi-cluster provisioning and upgrades
  • Works across on-premises and cloud environments
  • Offers clusterctl and Operator management paths

Limits

  • Requires an existing Kubernetes cluster accessible through kubectl
  • Does not manage clusters spanning multiple infrastructure providers
  • Does not manage clusters it did not provision

Who it suits

Cluster API is intended for platform operators managing Kubernetes cluster lifecycles. It is suited to teams with an existing Kubernetes management cluster and responsibility for their control planes.

Verdict

Cluster API provides declarative lifecycle tooling for Kubernetes clusters, with interchangeable provider components and two management paths. Provider components and infrastructure costs depend on the selected providers.

Where Specifiction places it

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