Add CAPI patch to support in-place upgrade in KCP

projects/kubernetes-sigs/cluster-api/patches/0037-Add-support-for-in-place-upgrade-in-KCP.patch

@@ -0,0 +1,102 @@
+From 4efd2b227eb3f4bc34101f7c948078f191c49d2a Mon Sep 17 00:00:00 2001
+From: Abhinav Pandey <[email protected]>
+Date: Wed, 17 Jan 2024 00:50:28 -0800
+Subject: [PATCH] Add support for in-place upgrade in KCP
+
+---
+ .../kubeadm/api/v1beta1/kubeadm_control_plane_types.go    | 8 ++++++++
+ .../kubeadm/api/v1beta1/kubeadm_control_plane_webhook.go  | 6 +++++-
+ controlplane/kubeadm/internal/controllers/upgrade.go      | 8 +++++++-
+ 3 files changed, 20 insertions(+), 2 deletions(-)
+
+diff --git a/controlplane/kubeadm/api/v1beta1/kubeadm_control_plane_types.go b/controlplane/kubeadm/api/v1beta1/kubeadm_control_plane_types.go
+index 5272b0e5a..933d87f8a 100644
+--- a/controlplane/kubeadm/api/v1beta1/kubeadm_control_plane_types.go
++++ b/controlplane/kubeadm/api/v1beta1/kubeadm_control_plane_types.go
+@@ -35,6 +35,9 @@ const (
+ 	// RollingUpdateStrategyType replaces the old control planes by new one using rolling update
+ 	// i.e. gradually scale up or down the old control planes and scale up or down the new one.
+ 	RollingUpdateStrategyType RolloutStrategyType = "RollingUpdate"
++
++	// InPlaceUpgradeStrategyType updates the node in place by delegating the upgrade to an external entity.
++	InPlaceUpgradeStrategyType RolloutStrategyType = "InPlace"
+ )
+
+ const (
+@@ -65,6 +68,11 @@ const (
+ 	// failures in updating remediation retry (the counter restarts from zero).
+ 	RemediationForAnnotation = "controlplane.cluster.x-k8s.io/remediation-for"
+
++	// InPlaceUpgradeAnnotation is used to denote that the KCP object needs to be in-place upgraded by an external entity.
++	// This annotation will be added to the KCP object when `rolloutStrategy.type` is set to `InPlace`.
++	// The external upgrader entity should watch for the annoatation and trigger an upgrade when it's added.
++	InPlaceUpgradeAnnotation = "controlplane.clusters.x-k8s.io/in-place-upgrade-needed"
++
+ 	// DefaultMinHealthyPeriod defines the default minimum period before we consider a remediation on a
+ 	// machine unrelated from the previous remediation.
+ 	DefaultMinHealthyPeriod = 1 * time.Hour
+diff --git a/controlplane/kubeadm/api/v1beta1/kubeadm_control_plane_webhook.go b/controlplane/kubeadm/api/v1beta1/kubeadm_control_plane_webhook.go
+index 83bf26356..f7d0f6635 100644
+--- a/controlplane/kubeadm/api/v1beta1/kubeadm_control_plane_webhook.go
++++ b/controlplane/kubeadm/api/v1beta1/kubeadm_control_plane_webhook.go
+@@ -381,12 +381,16 @@ func validateRolloutStrategy(rolloutStrategy *RolloutStrategy, replicas *int32,
+ 		return allErrs
+ 	}
+
++	if rolloutStrategy.Type == InPlaceUpgradeStrategyType {
++		return allErrs
++	}
++
+ 	if rolloutStrategy.Type != RollingUpdateStrategyType {
+ 		allErrs = append(
+ 			allErrs,
+ 			field.Required(
+ 				pathPrefix.Child("type"),
+-				"only RollingUpdateStrategyType is supported",
++				"only RollingUpdateStrategyType and InPlaceUpgradeStrategyType are supported",
+ 			),
+ 		)
+ 	}
+diff --git a/controlplane/kubeadm/internal/controllers/upgrade.go b/controlplane/kubeadm/internal/controllers/upgrade.go
+index 200a27174..181e4dd1c 100644
+--- a/controlplane/kubeadm/internal/controllers/upgrade.go
++++ b/controlplane/kubeadm/internal/controllers/upgrade.go
+@@ -18,6 +18,7 @@ package controllers
+
+ import (
+ 	"context"
++	"time"
+
+ 	"github.com/blang/semver"
+ 	"github.com/pkg/errors"
+@@ -26,6 +27,7 @@ import (
+ 	controlplanev1 "sigs.k8s.io/cluster-api/controlplane/kubeadm/api/v1beta1"
+ 	"sigs.k8s.io/cluster-api/controlplane/kubeadm/internal"
+ 	"sigs.k8s.io/cluster-api/util"
++	"sigs.k8s.io/cluster-api/util/annotations"
+ 	"sigs.k8s.io/cluster-api/util/collections"
+ 	"sigs.k8s.io/cluster-api/util/version"
+ )
+@@ -37,7 +39,7 @@ func (r *KubeadmControlPlaneReconciler) upgradeControlPlane(
+ ) (ctrl.Result, error) {
+ 	logger := ctrl.LoggerFrom(ctx)
+
+-	if controlPlane.KCP.Spec.RolloutStrategy == nil || controlPlane.KCP.Spec.RolloutStrategy.RollingUpdate == nil {
++	if controlPlane.KCP.Spec.RolloutStrategy == nil {
+ 		return ctrl.Result{}, errors.New("rolloutStrategy is not set")
+ 	}
+
+@@ -133,6 +135,10 @@ func (r *KubeadmControlPlaneReconciler) upgradeControlPlane(
+ 			return r.scaleUpControlPlane(ctx, controlPlane)
+ 		}
+ 		return r.scaleDownControlPlane(ctx, controlPlane, machinesRequireUpgrade)
++	case controlplanev1.InPlaceUpgradeStrategyType:
++		annotations.AddAnnotations(controlPlane.KCP, map[string]string{controlplanev1.InPlaceUpgradeAnnotation: ""})
++		logger.Info("RolloutStrategy.Type set to `InPlace`, adding the annotation an requeuing the request in 30 seconds")
++		return ctrl.Result{RequeueAfter: time.Second * 30}, nil
+ 	default:
+ 		logger.Info("RolloutStrategy type is not set to RollingUpdateStrategyType, unable to determine the strategy for rolling out machines")
+ 		return ctrl.Result{}, nil
+-- 
+2.42.0
+