Allow to disable CPLB load balancer

This is one of the remaining tasks of k0sproject#5279. The intended use case for this is to allow to use the VIPs functionality while using some user provided load balancer such as HAProxy, nginx, etc... Also fixes some CPLB documentation mistakes spotted while fixing this. Signed-off-by: Juan-Luis de Sousa-Valadas Castaño <[email protected]> mend
juanluisvaladas · Jan 2, 2025 · 718d50d · 718d50d
1 parent d43f482
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diff --git a/docs/configuration.md b/docs/configuration.md
@@ -318,10 +318,12 @@ Configuration options related to k0s's [control plane load balancing] feature
 
 Configuration options related to keepalived in [control plane load balancing]
 
-| Element          | Description                                                                                                 |
-| ---------------- | ----------------------------------------------------------------------------------------------------------- |
-| `vrrpInstances`  | Configuration options related to the VRRP. This is an array which allows to configure multiple virtual IPs. |
-| `virtualServers` | Configuration options related LoadBalancing. This is an array which allows to configure multiple LBs.       |
+| Element                  | Description                                                                                                                          |
+| ------------------------ | ------------------------------------------------------------------------------------------------------------------------------------ |
+| `vrrpInstances`          | Configuration options related to the VRRP. This is an array which allows to configure multiple virtual IPs.                          |
+| `virtualServers`         | Configuration options related LoadBalancing. This is an array which allows to configure multiple LBs.                                |
+| `userSpaceProxyBindPort` | The port where the userspace proxy will bind to. This port is for internal use only but listens on every interface. Default: `6443`  |
+| `disableLoadBalancer`    | Disables the load balancer. Default: `false`                                                                                         |
 
 ##### `spec.network.controlPlaneLoadBalancing.keepalived.vrrpInstances`
 

diff --git a/pkg/apis/k0s/v1beta1/cplb.go b/pkg/apis/k0s/v1beta1/cplb.go
@@ -68,13 +68,16 @@ type KeepalivedSpec struct {
 	// which allows to configure multiple load balancers.
 	VirtualServers VirtualServers `json:"virtualServers,omitempty"`
 	// UserspaceProxyPort is the port where the userspace proxy will bind
-	// to. This port is only exposed on the localhost interface and is only
-	// used internally. Defaults to 6444.
+	// to. This port is onlyis only used internally. Defaults to 6444, but
+	// listens in every interface
 	// +kubebuilder:default=6444
 	// +kubebuilder:validation:Minimum=1
 	// +kubebuilder:validation:Maximum=65535
 	// +optional
 	UserSpaceProxyPort int `json:"userSpaceProxyBindPort,omitempty"`
+	// DisableLoadBalanmcer disables the load balancer.
+	// +optional
+	DisableLoadBalancer bool `json:"disableLoadBalancer,omitempty"`
 }
 
 // VRRPInstances is a list of VRRPInstance

diff --git a/pkg/component/controller/cplb/cplb_linux.go b/pkg/component/controller/cplb/cplb_linux.go
@@ -100,13 +100,15 @@ func (k *Keepalived) Start(ctx context.Context) error {
 		}
 	}
 
-	if len(k.Config.VRRPInstances) > 0 || len(k.Config.VirtualServers) > 0 {
-		k.log.Info("Starting CPLB reconciler")
-		updateCh := make(chan struct{}, 1)
-		k.reconciler = NewCPLBReconciler(k.KubeConfigPath, updateCh)
-		k.updateCh = updateCh
-		if err := k.reconciler.Start(); err != nil {
-			return fmt.Errorf("failed to start CPLB reconciler: %w", err)
+	if !k.Config.DisableLoadBalancer {
+		if len(k.Config.VRRPInstances) > 0 || len(k.Config.VirtualServers) > 0 {
+			k.log.Info("Starting CPLB reconciler")
+			updateCh := make(chan struct{}, 1)
+			k.reconciler = NewCPLBReconciler(k.KubeConfigPath, updateCh)
+			k.updateCh = updateCh
+			if err := k.reconciler.Start(); err != nil {
+				return fmt.Errorf("failed to start CPLB reconciler: %w", err)
+			}
 		}
 	}
 
@@ -160,6 +162,7 @@ func (k *Keepalived) Start(ctx context.Context) error {
 			}
 		}()
 	}
+
 	return k.supervisor.Supervise()
 }
 

diff --git a/static/_crds/k0s/k0s.k0sproject.io_clusterconfigs.yaml b/static/_crds/k0s/k0s.k0sproject.io_clusterconfigs.yaml
@@ -508,6 +508,9 @@ spec:
                           Keepalived contains configuration options related to the "Keepalived" type
                           of load balancing.
                         properties:
+                          disableLoadBalancer:
+                            description: DisableLoadBalanmcer disables the load balancer.
+                            type: boolean
                           userSpaceProxyBindPort:
                             default: 6444
                             description: |-