Add spec.api.bindAddress configuration

Signed-off-by: Alex Hutchins <gakio12@gmail.com>
Signed-off-by: gakio12 <gakio12@gmail.com>
Signed-off-by: Phillip Schichtel <phillip@schich.tel>

cmd/controller/certificates.go

@@ -63,7 +63,7 @@ func (c *Certificates) Init(ctx context.Context) error {
 		return fmt.Errorf("failed to read ca cert: %w", err)
 	}
 	c.CACert = string(cert)
-	kubeConfigAPIUrl := fmt.Sprintf("https://localhost:%d", c.ClusterSpec.API.Port)
+	kubeConfigAPIUrl := fmt.Sprintf("https://%s:%d", c.ClusterSpec.API.APIServerAddress(), c.ClusterSpec.API.Port)
 	eg.Go(func() error {
 		// Front proxy CA
 		if err := c.CertManager.EnsureCA("front-proxy-ca", "kubernetes-front-proxy-ca"); err != nil {

cmd/controller/controller.go

@@ -185,6 +185,7 @@ func (c *command) start(ctx context.Context) error {
 	}
 
 	logrus.Infof("using api address: %s", nodeConfig.Spec.API.Address)
+	logrus.Infof("using api bind-address: %s", nodeConfig.Spec.API.BindAddress)
 	logrus.Infof("using listen port: %d", nodeConfig.Spec.API.Port)
 	logrus.Infof("using sans: %s", nodeConfig.Spec.API.SANs)
 

docs/configuration.md

@@ -55,6 +55,7 @@ spec:
     externalAddress: my-lb-address.example.com
     k0sApiPort: 9443
     port: 6443
+    bindAddress: 192.0.2.1
     sans:
     - 192.168.68.104
   controllerManager: {}
@@ -124,9 +125,10 @@ spec:
 ### `spec.api`
 
 | Element                  | Description                                                                                                                                                                                                                 |
-| ------------------------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+|--------------------------| --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
 | `externalAddress`        | The loadbalancer address (for k0s controllers running behind a loadbalancer). Configures all cluster components to connect to this address and also configures this address for use  when joining new nodes to the cluster. |
-| `address`                | Local address on which to bind an API. Also serves as one of the addresses pushed on the k0s create service certificate on the API. Defaults to first non-local address found on the node.                                  |
+| `address`                | Local address on which to bind an API. Also serves as one of the addresses pushed on the k0s create service certificate on the API. Defaults to first non-local address found on the node.                                 |
+| `bindAddress`            | The IP address for the Kubernetes API server to to listen on. The associated interface(s) must be reachable by the rest of the cluster. Will be added as an additional subject alternative name to the API server's TLS certificate. If blank or an unspecified address (`0.0.0.0` or `::`), all interfaces and IP address families will be used. This is effectively the value for the API server's `--bind-address` CLI flag.    |
 | `sans`                   | List of additional addresses to push to API servers serving the certificate.                                                                                                                                                |
 | `extraArgs`              | Map of key-values (strings) for any extra arguments to pass down to Kubernetes api-server process.                                                                                                                          |
 | `port`¹                  | Custom port for kube-api server to listen on (default: 6443)                                                                                                                                                                |

pkg/apis/k0s/v1beta1/api.go

@@ -35,6 +35,10 @@ type APISpec struct {
 	// Local address on which to bind an API
 	Address string `json:"address"`
 
+	// The IP address for the Kubernetes API server to to listen on.
+	// +kubebuilder:validation:Pattern=`^([0-9.]+|[0-9a-fA-F:%]+)$`
+	BindAddress string `json:"bindAddress,omitempty"`
+
 	// The loadbalancer address (for k0s controllers running behind a loadbalancer)
 	ExternalAddress string `json:"externalAddress,omitempty"`
 	// Map of key-values (strings) for any extra arguments to pass down to Kubernetes api-server process
@@ -57,11 +61,12 @@ func DefaultAPISpec() *APISpec {
 	addresses, _ := iface.AllAddresses()
 	publicAddress, _ := iface.FirstPublicAddress()
 	return &APISpec{
-		Port:       defaultKasPort,
-		K0sAPIPort: 9443,
-		SANs:       addresses,
-		Address:    publicAddress,
-		ExtraArgs:  make(map[string]string),
+		Port:        defaultKasPort,
+		K0sAPIPort:  9443,
+		BindAddress: "0.0.0.0",
+		SANs:        addresses,
+		Address:     publicAddress,
+		ExtraArgs:   make(map[string]string),
 	}
 }
 
@@ -100,10 +105,21 @@ func (a *APISpec) getExternalURIForPort(port int) string {
 	return fmt.Sprintf("https://%s:%d", addr, port)
 }
 
+// APIServerAddress returns the address the API is listening on
+func (a *APISpec) APIServerAddress() string {
+	if a.BindAddress == "" {
+		return "localhost"
+	}
+	return a.BindAddress
+}
+
 // Sans return the given SANS plus all local adresses and externalAddress if given
 func (a *APISpec) Sans() []string {
 	sans, _ := iface.AllAddresses()
 	sans = append(sans, a.Address)
+	if a.BindAddress != "" {
+		sans = append(sans, a.BindAddress)
+	}
 	sans = append(sans, a.SANs...)
 	if a.ExternalAddress != "" {
 		sans = append(sans, a.ExternalAddress)
@@ -139,5 +155,10 @@ func (a *APISpec) Validate() []error {
 	if a.ExternalAddress != "" {
 		validateIPAddressOrDNSName(field.NewPath("externalAddress"), a.ExternalAddress)
 	}
+
+	if a.BindAddress != "" && !govalidator.IsIP(a.BindAddress) {
+		errors = append(errors, field.Invalid(field.NewPath("bindAddress"), a.BindAddress, "invalid IP address"))
+	}
+
 	return errors
 }

pkg/apis/k0s/v1beta1/api_test.go

@@ -35,7 +35,8 @@ func (s *APISuite) TestValidation() {
 
 	s.T().Run("accepts_ipv6_as_address", func(t *testing.T) {
 		a := APISpec{
-			Address: "2001:0db8:85a3:0000:0000:8a2e:0370:7334",
+			Address:     "2001:0db8:85a3:0000:0000:8a2e:0370:7334",
+			BindAddress: "2001:0db8:85a3:0000:0000:8a2e:0370:7334",
 		}
 
 		s.Nil(a.Validate())
@@ -44,7 +45,8 @@ func (s *APISuite) TestValidation() {
 
 	s.T().Run("invalid_api_address", func(t *testing.T) {
 		a := APISpec{
-			Address: "something.that.is.not.valid//(())",
+			Address:     "something.that.is.not.valid//(())",
+			BindAddress: "0.0.0.0",
 		}
 
 		errors := a.Validate()
@@ -56,7 +58,8 @@ func (s *APISuite) TestValidation() {
 
 	s.T().Run("invalid_sans_address", func(t *testing.T) {
 		a := APISpec{
-			Address: "1.2.3.4",
+			Address:     "1.2.3.4",
+			BindAddress: "0.0.0.0",
 			SANs: []string{
 				"something.that.is.not.valid//(())",
 			},
@@ -68,6 +71,18 @@ func (s *APISuite) TestValidation() {
 			s.ErrorContains(errors[0], `sans[0]: Invalid value: "something.that.is.not.valid//(())": invalid IP address / DNS name`)
 		}
 	})
+
+	s.T().Run("invalid_api_bind_address", func(t *testing.T) {
+		a := APISpec{
+			Address:     "1.2.3.4",
+			BindAddress: "somehting.that.is.not.valid//(())",
+		}
+
+		errors := a.Validate()
+		s.NotNil(errors)
+		s.Len(errors, 1)
+		s.Contains(errors[0].Error(), "is not IP address")
+	})
 }
 
 func TestApiSuite(t *testing.T) {

pkg/component/controller/apiserver.go

@@ -125,6 +125,10 @@ func (a *APIServer) Start(_ context.Context) error {
 		"enable-admission-plugins":         "NodeRestriction",
 	}
 
+	if a.ClusterConfig.Spec.API.BindAddress != "" {
+		args["bind-address"] = a.ClusterConfig.Spec.API.BindAddress
+	}
+
 	apiAudiences := []string{"https://kubernetes.default.svc"}
 
 	if a.EnableKonnectivity {
@@ -229,7 +233,7 @@ func (a *APIServer) Ready() error {
 		TLSClientConfig: tlsConfig,
 	}
 	client := &http.Client{Transport: tr}
-	resp, err := client.Get(fmt.Sprintf("https://localhost:%d/readyz?verbose", a.ClusterConfig.Spec.API.Port))
+	resp, err := client.Get(fmt.Sprintf("https://%s:%d/readyz?verbose", a.ClusterConfig.Spec.API.APIServerAddress(), a.ClusterConfig.Spec.API.Port))
 	if err != nil {
 		return err
 	}

static/manifests/v1beta1/CustomResourceDefinition/k0s.k0sproject.io_clusterconfigs.yaml

@@ -40,6 +40,11 @@ spec:
                   address:
                     description: Local address on which to bind an API
                     type: string
+                  bindAddress:
+                    description: The IP address for the Kubernetes API server to to
+                      listen on.
+                    pattern: ^([0-9.]+|[0-9a-fA-F:%]+)$
+                    type: string
                   externalAddress:
                     description: The loadbalancer address (for k0s controllers running
                       behind a loadbalancer)