Kubernetes — Deployment & Life Cycle

Kubernetes

Published

May 13, 2025

Modified

May 13, 2025

Overview

Cluster API project¹ …automate Kubernetes cluster lifecycle

What is Cluster API?
- …use Kubernets to run other Kubernetes clusters
- …make cluster life cycle management easy
Declarative, Kubernetes-style APIs…
- …cluster creation, configuration, and management
- …consistent & repeatable cluster deployments
- …on-premises & cloud infrastructure
Extendable to support any provider implementation²
- …production ready since 2021/10
- …widespread community supports Red Hat, Amazon, Hetzner, etc.

Architecture

Cluster API Intro and Deep Dive - Yuvaraj Balaji Rao Kakaraparthi, Vince Prignano, KubeCon North America 2022

Concepts & terminology³…

Management cluster
- …Kubernetes cluster that manages the lifecycle of Workload Clusters
- …hosts infrastructure, bootstrap & machine providers
Infrastructure provider
- …provisioning of infrastructure/computational resources
- …cloud infrastructure providers: AWS, Azure, Google…
- …bare-metal providers: Rancher, Metal3…
Bootstrap provider
- …configure a node for Kubernetes
- …generate PKI certificates
- …initialize control plane
- …join control plane & worker nodes to a cluster
Control plane
- …serve the Kubernetes API …reconcile desired state
- …self-porvisioned (for example by kubeadm)
- …pod-based, requires a hosting (management) cluster

Cluster API (CAPI)

Implemented as CRDs & controllers

…grouped into the Cluster API core manager and several types of “providers”
Custom Resource Definitions (CRDs)
- Cluster …represents a Kubernetes cluster
- MachineDeployment …definition for a managed set of machines
- MachineSet …represents a group of machines
- Machine …represents a Kubernetes node
- MachineHealthCheck …identifies when a node is unhealthy

Installation

Requires an existing Kubernetes cluster …accessible via kubectl

…installation transforms it into a management cluster…
…by deploying the Cluster API provider components
Best practice …bootstrap & pivot⁴
- …create a temporary (local) bootstrap cluster
- …make the bootstrap cluster a temporary management cluster
- …use the temporary management cluster to establish a workload cluster
- …convert the workload cluster into a permanent management cluster
- …delete the temporary bootstrap cluster

Install a recent clusterctl⁵ release from GitHub⁶:

# list of supported providers
clusterctl config repositories

# configure the management cluster
clusterctl init #…

# inspect the deployments created
kubectl get deploy -A | grep "cap\|cert"

clusterctl init⁷ — define the management cluster
- …require/installs a cert-manager
- …installs the Cluster API components …including capi-system
- …adds the cluster-api core provider & kubeadm bootstrap provider
- …installs each provider in the default target namespace …prefix capi-
After installing the providers…
- …move on to cluster creation …to deploy a workload cluster
- …define a cluster object …to specify nodes, etc.

Docker (CAPD)

# list variables in the components YAML manifests
clusterctl generate provider -i docker --describe

# initialize the management cluster
export CLUSTER_TOPOLOGY=true
clusterctl init --infrastructure docker

Generating a CAPD (Docker) managed cluster manifest:

clusterctl generate cluster capd-demo \
      --flavor development \
      --infrastructure docker \
      --kubernetes-version v1.32.0 \
      --control-plane-machine-count=3 \
      --worker-machine-count=3 > capd-demo.yaml
kubectl apply -f capd-demo.yaml

# check if the cluster starts provisioning
kubectl get cluster
clusterctl describe cluster capd-demo

# clean up
kubectl delete cluster capd-demo

Footnotes

Kubernetes Cluster API
https://cluster-api.sigs.k8s.io/
https://github.com/kubernetes/community/tree/master/sig-cluster-lifecycle ↩︎
Provider Implementations, The Cluster API Book
https://cluster-api.sigs.k8s.io/reference/providers ↩︎
Concepts, The Cluster API Book
https://cluster-api.sigs.k8s.io/user/concepts ↩︎
clusterctl move command, The Cluster API Book
https://cluster-api.sigs.k8s.io/clusterctl/commands/move.html#bootstrap--pivot ↩︎
Install clusterctl, The Cluster API Book
https://cluster-api.sigs.k8s.io/user/quick-start#install-clusterctl ↩︎
Cluster API Releases, Github
https://github.com/kubernetes-sigs/cluster-api/releases ↩︎
cluster init command, The Cluster API Book
https://cluster-api.sigs.k8s.io/clusterctl/commands/init ↩︎

--- title: Kubernetes — Deployment & Life Cycle categories: - Kubernetes date: 2025/05/13 date-modified: 2025/05/13 toc-expand: 3 --- ## Overview **Cluster API project**[^df51D] …automate Kubernetes cluster lifecycle - _What is Cluster API?_ - …use Kubernets to run other Kubernetes clusters - …make cluster life cycle management easy - Declarative, Kubernetes-style APIs… - …cluster creation, configuration, and management - …consistent & repeatable cluster deployments - …on-premises & cloud infrastructure - Extendable to support any provider implementation[^7jKl1] - …production ready since 2021/10 - …widespread community supports Red Hat, Amazon, Hetzner, etc. [^df51D]: Kubernetes Cluster API <https://cluster-api.sigs.k8s.io/> <https://github.com/kubernetes/community/tree/master/sig-cluster-lifecycle> [^7jKl1]: Provider Implementations, The Cluster API Book <https://cluster-api.sigs.k8s.io/reference/providers> ### Architecture ![Cluster API Intro and Deep Dive - Yuvaraj Balaji Rao Kakaraparthi, Vince Prignano, KubeCon North America 2022](capi-management-cluster.png){.lightbox fig-align="center"} Concepts & terminology[^k0Ld2]… - **Management cluster** - …Kubernetes cluster that manages the lifecycle of **Workload Clusters** - …hosts infrastructure, bootstrap & machine providers - **Infrastructure provider** - …provisioning of infrastructure/computational resources - …cloud infrastructure providers: AWS, Azure, Google… - …bare-metal providers: Rancher, Metal3… - **Bootstrap provider** - …configure a node for Kubernetes - …generate PKI certificates - …initialize control plane - …join control plane & worker nodes to a cluster - **Control plane** - …serve the Kubernetes API …reconcile desired state - …self-porvisioned (for example by `kubeadm`) - …pod-based, requires a hosting (management) cluster [^k0Ld2]: Concepts, The Cluster API Book <https://cluster-api.sigs.k8s.io/user/concepts> ### Cluster API (CAPI) Implemented as CRDs & controllers - …grouped into the Cluster API core manager and several types of “providers” - Custom Resource Definitions (CRDs) - `Cluster` …represents a Kubernetes cluster - `MachineDeployment` …definition for a managed set of machines - `MachineSet` …represents a group of machines - `Machine` …represents a Kubernetes node - `MachineHealthCheck` …identifies when a node is unhealthy ## Installation Requires an existing Kubernetes cluster …accessible via kubectl - …installation transforms it into a management cluster… - …by deploying the Cluster API provider components - Best practice …bootstrap & pivot[^d3Fg5] - …create a temporary (local) **bootstrap cluster** - …make the bootstrap cluster a temporary management cluster - …use the temporary management cluster to establish a workload cluster - …convert the workload cluster into a permanent management cluster - …delete the temporary bootstrap cluster [^d3Fg5]: `clusterctl move` command, The Cluster API Book <https://cluster-api.sigs.k8s.io/clusterctl/commands/move.html#bootstrap--pivot> Install a recent `clusterctl`[^g5J3k] release from GitHub[^9klJg]: [^g5J3k]: Install `clusterctl`, The Cluster API Book <https://cluster-api.sigs.k8s.io/user/quick-start#install-clusterctl> [^9klJg]: Cluster API Releases, Github <https://github.com/kubernetes-sigs/cluster-api/releases> ```bash # list of supported providers clusterctl config repositories # configure the management cluster clusterctl init #… # inspect the deployments created kubectl get deploy -A | grep "cap\|cert" ``` - `clusterctl init`[^4gFHi] — define the management cluster - …require/installs a `cert-manager` - …installs the Cluster API components …including `capi-system` - …adds the `cluster-api` core provider & `kubeadm` bootstrap provider - …installs each provider in the default target namespace …prefix `capi-` - After installing the providers… - …move on to cluster creation …to deploy a workload cluster - …define a cluster object …to specify nodes, etc. ### Docker (CAPD) ```bash # list variables in the components YAML manifests clusterctl generate provider -i docker --describe # initialize the management cluster export CLUSTER_TOPOLOGY=true clusterctl init --infrastructure docker ``` [^4gFHi]: `cluster init` command, The Cluster API Book <https://cluster-api.sigs.k8s.io/clusterctl/commands/init> Generating a CAPD (Docker) managed cluster manifest: ```bash clusterctl generate cluster capd-demo \ --flavor development \ --infrastructure docker \ --kubernetes-version v1.32.0 \ --control-plane-machine-count=3 \ --worker-machine-count=3 > capd-demo.yaml kubectl apply -f capd-demo.yaml # check if the cluster starts provisioning kubectl get cluster clusterctl describe cluster capd-demo # clean up kubectl delete cluster capd-demo ```