Feature gate for old infra machine naming

There is a breaking change to the way infra machines are named in
v1.7.0. This commit adds a feature gate for getting the old behavior
back. It defaults to disabled so the new behavior stays. It is also
marked as deprecated so it can be removed in a future minor release.

Signed-off-by: Lennart Jern <[email protected]>

Author: lentzi90

.golangci.yml

@@ -243,6 +243,11 @@ issues:
   - linters:
     - staticcheck
     text: "SA1019: (clusterv1alpha3.*|clusterv1alpha4.*) is deprecated: This type will be removed in one of the next releases."
+  # Specific exclude rules for deprecated featuregates that are still part of the codebase. These
+  # should be removed as the referenced deprecated types are removed from the project.
+  - linters:
+    - staticcheck
+    text: "SA1019: (feature.InfraMachineNameFromTemplate) is deprecated: This type will be removed in one of the next releases."
   - linters:
     - revive
     text: "exported: exported method .*\\.(Reconcile|SetupWithManager|SetupWebhookWithManager) should have comment or be unexported"

config/manager/manager.yaml

@@ -23,7 +23,7 @@ spec:
             - "--leader-elect"
             - "--diagnostics-address=${CAPI_DIAGNOSTICS_ADDRESS:=:8443}"
             - "--insecure-diagnostics=${CAPI_INSECURE_DIAGNOSTICS:=false}"
-            - "--feature-gates=MachinePool=${EXP_MACHINE_POOL:=true},ClusterResourceSet=${EXP_CLUSTER_RESOURCE_SET:=true},ClusterTopology=${CLUSTER_TOPOLOGY:=false},RuntimeSDK=${EXP_RUNTIME_SDK:=false},MachineSetPreflightChecks=${EXP_MACHINE_SET_PREFLIGHT_CHECKS:=false}"
+            - "--feature-gates=MachinePool=${EXP_MACHINE_POOL:=true},ClusterResourceSet=${EXP_CLUSTER_RESOURCE_SET:=true},ClusterTopology=${CLUSTER_TOPOLOGY:=false},RuntimeSDK=${EXP_RUNTIME_SDK:=false},MachineSetPreflightChecks=${EXP_MACHINE_SET_PREFLIGHT_CHECKS:=false},InfraMachineNameFromTemplate=${INFRA_MACHINE_NAME_FROM_TEMPLATE:=false}"
           image: controller:latest
           name: manager
           env:

controlplane/kubeadm/config/manager/manager.yaml

@@ -22,7 +22,7 @@ spec:
             - "--leader-elect"
             - "--diagnostics-address=${CAPI_DIAGNOSTICS_ADDRESS:=:8443}"
             - "--insecure-diagnostics=${CAPI_INSECURE_DIAGNOSTICS:=false}"
-            - "--feature-gates=MachinePool=${EXP_MACHINE_POOL:=true},ClusterTopology=${CLUSTER_TOPOLOGY:=false},KubeadmBootstrapFormatIgnition=${EXP_KUBEADM_BOOTSTRAP_FORMAT_IGNITION:=false}"
+            - "--feature-gates=MachinePool=${EXP_MACHINE_POOL:=true},ClusterTopology=${CLUSTER_TOPOLOGY:=false},KubeadmBootstrapFormatIgnition=${EXP_KUBEADM_BOOTSTRAP_FORMAT_IGNITION:=false},InfraMachineNameFromTemplate=${INFRA_MACHINE_NAME_FROM_TEMPLATE:=false}"
           image: controller:latest
           name: manager
           env:

controlplane/kubeadm/internal/controllers/helpers.go

@@ -37,6 +37,7 @@ import (
 	"sigs.k8s.io/cluster-api/controllers/external"
 	controlplanev1 "sigs.k8s.io/cluster-api/controlplane/kubeadm/api/v1beta1"
 	"sigs.k8s.io/cluster-api/controlplane/kubeadm/internal"
+	"sigs.k8s.io/cluster-api/feature"
 	"sigs.k8s.io/cluster-api/internal/util/ssa"
 	"sigs.k8s.io/cluster-api/util"
 	"sigs.k8s.io/cluster-api/util/certs"
@@ -180,12 +181,16 @@ func (r *KubeadmControlPlaneReconciler) cloneConfigsAndGenerateMachine(ctx conte
 		UID:        kcp.UID,
 	}
 
+	infraMachineName := machine.Name
+	if feature.Gates.Enabled(feature.InfraMachineNameFromTemplate) {
+		infraMachineName = names.SimpleNameGenerator.GenerateName(kcp.Spec.MachineTemplate.InfrastructureRef.Name)
+	}
 	// Clone the infrastructure template
 	infraRef, err := external.CreateFromTemplate(ctx, &external.CreateFromTemplateInput{
 		Client:      r.Client,
 		TemplateRef: &kcp.Spec.MachineTemplate.InfrastructureRef,
 		Namespace:   kcp.Namespace,
-		Name:        machine.Name,
+		Name:        infraMachineName,
 		OwnerRef:    infraCloneOwner,
 		ClusterName: cluster.Name,
 		Labels:      internal.ControlPlaneMachineLabelsForCluster(kcp, cluster.Name),

feature/feature.go

@@ -61,6 +61,13 @@ const (
 	//
 	// alpha: v1.5
 	MachineSetPreflightChecks featuregate.Feature = "MachineSetPreflightChecks"
+
+	// InfraMachineNameFromTemplate is a feature gate for the now deprecated way of naming infra machines.
+	// With this feature gate enabled, infra machines will be named based on the infra machine template.
+	// The new behavior is that they get the same name as the machine.
+	//
+	// Deprecated: v1.7.
+	InfraMachineNameFromTemplate featuregate.Feature = "InfraMachineNameFromTemplate"
 )
 
 func init() {
@@ -77,4 +84,5 @@ var defaultClusterAPIFeatureGates = map[featuregate.Feature]featuregate.FeatureS
 	KubeadmBootstrapFormatIgnition: {Default: false, PreRelease: featuregate.Alpha},
 	RuntimeSDK:                     {Default: false, PreRelease: featuregate.Alpha},
 	MachineSetPreflightChecks:      {Default: false, PreRelease: featuregate.Alpha},
+	InfraMachineNameFromTemplate:   {Default: false, PreRelease: featuregate.Deprecated},
 }

internal/controllers/machineset/machineset_controller.go

@@ -43,6 +43,7 @@ import (
 	"sigs.k8s.io/cluster-api/controllers/external"
 	"sigs.k8s.io/cluster-api/controllers/noderefutil"
 	"sigs.k8s.io/cluster-api/controllers/remote"
+	"sigs.k8s.io/cluster-api/feature"
 	"sigs.k8s.io/cluster-api/internal/contract"
 	"sigs.k8s.io/cluster-api/internal/controllers/machine"
 	"sigs.k8s.io/cluster-api/internal/util/ssa"
@@ -497,12 +498,16 @@ func (r *Reconciler) syncReplicas(ctx context.Context, cluster *clusterv1.Cluste
 				log = log.WithValues(bootstrapRef.Kind, klog.KRef(bootstrapRef.Namespace, bootstrapRef.Name))
 			}
 
+			infraMachineName := machine.Name
+			if feature.Gates.Enabled(feature.InfraMachineNameFromTemplate) {
+				infraMachineName = names.SimpleNameGenerator.GenerateName(ms.Spec.Template.Spec.InfrastructureRef.Name)
+			}
 			// Create the InfraMachine.
 			infraRef, err = external.CreateFromTemplate(ctx, &external.CreateFromTemplateInput{
 				Client:      r.UnstructuredCachingClient,
 				TemplateRef: &ms.Spec.Template.Spec.InfrastructureRef,
 				Namespace:   machine.Namespace,
-				Name:        machine.Name,
+				Name:        infraMachineName,
 				ClusterName: machine.Spec.ClusterName,
 				Labels:      machine.Labels,
 				Annotations: machine.Annotations,