kubernetes-sigs/cluster-api

Updating Cluster network configuration for single stack to dual-stack upgrades

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#6,951 opened on Jul 18, 2022

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Description

User Story

As an operator I would like to update the cluster network configuration for an existing Cluster resource for upgrading a single stack Cluster to a dual-stack Cluster.

Detailed Description

I'd like to be able to add the cidr range for an additional IP family to spec.clusterNetwork.pods.cidrBlocks and spec.clusterNetwork.services.cidrBlocks e.g If I have a single stack IPv4 cluster with IPv4 cidr ranges I'd like to be able to add IPv6 cidr ranges to the cidrBlocks to upgrade my cluster to a dual-stack cluster.

Updating the cidrBlocks on a Cluster needs to be able to reconcile the KubeadmControlPlane with the additional CIDRs. Right now it seems like the KubeadmControlPlane disallows changes to the clusterConfiguation.networking.{serviceSubnet,podSubnet} and updating the cidrBlocks on a Cluster also does not affect the KubeadmControlPlane.

Anything else you would like to add:

/kind feature

Contributor guide

Research direction
Investigate how KubeadmControlPlane reconciles network configuration changes and how to propagate CIDR updates from Cluster to KubeadmControlPlane. Focus on the upgrade path and node drain/re init considerations.
Tech stack
gokubernetes
Domain
backendinfrastructurenetworkingapi
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
3-5 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Mostly clear
Prerequisites
KubernetesGoCluster API
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30