Initial implementation

src/k8s/api/v1/types.go

@@ -19,6 +19,7 @@ type BootstrapConfig struct {
 	EnableRBAC          *bool  `yaml:"enable-rbac"`
 	K8sDqlitePort       int    `yaml:"k8s-dqlite-port"`
 	Datastore           string `yaml:"datastore"`
+	ExtraSANs           string `yaml:"extrasans"`
 	DatastoreURL        string `yaml:"datastore-url,omitempty"`
 	DatastoreCACert     string `yaml:"datastore-ca-crt,omitempty"`
 	DatastoreClientCert string `yaml:"datastore-client-crt,omitempty"`
@@ -33,6 +34,7 @@ func (b *BootstrapConfig) SetDefaults() {
 	b.EnableRBAC = vals.Pointer(true)
 	b.K8sDqlitePort = 9000
 	b.Datastore = "k8s-dqlite"
+	b.ExtraSANs = ""
 }
 
 // ToMap marshals the BootstrapConfig into yaml and map it to "bootstrapConfig".

src/k8s/cmd/k8s/k8s_bootstrap.go

@@ -150,6 +150,10 @@ func getConfigInteractively(stdin io.Reader, stdout io.Writer, stderr io.Writer)
 	config.ServiceCIDR = askQuestion(stdin, stdout, stderr, "Please set the Service CIDR:", nil, config.ServiceCIDR, nil)
 	rbac := askBool(stdin, stdout, stderr, "Enable Role Based Access Control (RBAC)?", []string{"yes", "no"}, "yes")
 	*config.EnableRBAC = rbac
+	extraSANs := askBool(stdin, stdout, stderr, "Set extra SANs for the certificates?", []string{"yes", "no"}, "no")
+	if extraSANs {
+		config.ExtraSANs = askQuestion(stdin, stdout, stderr, "Please set the Extra SANs:", nil, config.ExtraSANs, nil)
+	}
 	return config
 }
 

src/k8s/pkg/k8sd/app/hooks_bootstrap.go

@@ -216,6 +216,7 @@ func onBootstrapControlPlane(s *state.State, initConfig map[string]string) error
 	certificates := pki.NewControlPlanePKI(pki.ControlPlanePKIOpts{
 		Hostname:                  s.Name(),
 		IPSANs:                    append([]net.IP{nodeIP}, serviceIPs...),
+		ExtraSANs:                 cfg.Certificates.ExtraSANs,
 		Years:                     20,
 		AllowSelfSignedCA:         true,
 		IncludeMachineAddressSANs: true,

src/k8s/pkg/k8sd/pki/control_plane.go

@@ -4,6 +4,8 @@ import (
 	"crypto/x509/pkix"
 	"fmt"
 	"net"
+
+	"github.com/canonical/k8s/pkg/utils"
 )
 
 // ControlPlanePKI is a list of all certificates we require for a control plane node.
@@ -13,7 +15,8 @@ type ControlPlanePKI struct {
 	hostname                  string   // node name
 	ipSANs                    []net.IP // IP SANs for generated certificates
 	dnsSANs                   []string // DNS SANs for the certificates below
-	years                     int      // how many years the generated certificates will be valid for
+	extraSANs                 []string
+	years                     int // how many years the generated certificates will be valid for
 
 	CACert, CAKey                             string // CN=kubernetes-ca (self-signed)
 	FrontProxyCACert, FrontProxyCAKey         string // CN=kubernetes-front-proxy-ca (self-signed)
@@ -34,6 +37,7 @@ type ControlPlanePKIOpts struct {
 	Hostname                  string
 	DNSSANs                   []string
 	IPSANs                    []net.IP
+	ExtraSANs                 string
 	Years                     int
 	AllowSelfSignedCA         bool
 	IncludeMachineAddressSANs bool
@@ -44,11 +48,14 @@ func NewControlPlanePKI(opts ControlPlanePKIOpts) *ControlPlanePKI {
 		opts.Years = 1
 	}
 
+	userDefinedSANs := utils.GetExtraSANsFromString(opts.ExtraSANs)
+	userDefinedIpSANs, userDefinedDnsSANs := utils.SeparateSANs(userDefinedSANs)
+
 	return &ControlPlanePKI{
 		hostname:                  opts.Hostname,
 		years:                     opts.Years,
-		ipSANs:                    opts.IPSANs,
-		dnsSANs:                   opts.DNSSANs,
+		ipSANs:                    append(opts.IPSANs, userDefinedIpSANs...),
+		dnsSANs:                   append(opts.DNSSANs, userDefinedDnsSANs...),
 		allowSelfSignedCA:         opts.AllowSelfSignedCA,
 		includeMachineAddressSANs: opts.IncludeMachineAddressSANs,
 	}

src/k8s/pkg/k8sd/types/cluster_config.go

@@ -39,6 +39,7 @@ type Certificates struct {
 	APIServerKubeletClientKey  string `yaml:"apiserver-kubelet-client-key,omitempty"`
 	K8sDqliteCert              string `yaml:"k8s-dqlite-crt,omitempty"`
 	K8sDqliteKey               string `yaml:"k8s-dqlite-key,omitempty"`
+	ExtraSANs                  string `yaml:"extrasans,omitempty"`
 
 	DatastoreCACert     string `yaml:"datastore-ca-crt,omitempty"`
 	DatastoreClientCert string `yaml:"datastore-client-crt,omitempty"`

src/k8s/pkg/utils/certificate.go

@@ -0,0 +1,26 @@
+package utils
+
+import (
+	"net"
+	"strings"
+)
+
+func GetExtraSANsFromString(extraSANs string) []string {
+	// TODO: Add validation for the extraSANs
+	return strings.Split(extraSANs, ",")
+}
+
+func SeparateSANs(extraSANs []string) ([]net.IP, []string) {
+	var ipSANs []net.IP
+	var dnsSANs []string
+
+	for _, san := range extraSANs {
+		if ip := net.ParseIP(san); ip != nil {
+			ipSANs = append(ipSANs, ip)
+		} else {
+			dnsSANs = append(dnsSANs, san)
+		}
+	}
+
+	return ipSANs, dnsSANs
+}