Add TLS support for k8s middleware (#289)

* Added TLS to k8s client

Added options for TLS kubernetes client connection.

* Fix k8s TLS config option parsing

Brings config option parsing for kubernetes TLS in line with recent changes.

* Put TLS config on one line

Put kubernetes tls config on one line to match style established in etcd tls config.

* Add tls option to README

middleware/kubernetes/README.md

@@ -40,7 +40,9 @@ This is the default kubernetes setup, with everything specified in full:
         # Example values: 60s, 5m, 1h
         resyncperiod 5m
         # Use url for k8s API endpoint
-        endpoint http://localhost:8080
+        endpoint https://k8sendpoint:8080
+	# The tls cert, key and the CA cert filenames
+	tls cert key cacert
         # Assemble k8s record names with the template
         template {service}.{namespace}.{zone}
         # Only expose the k8s namespace "demo"

middleware/kubernetes/kubernetes.go

@@ -18,6 +18,7 @@ import (
 	"k8s.io/kubernetes/pkg/api"
 	unversionedapi "k8s.io/kubernetes/pkg/api/unversioned"
 	unversionedclient "k8s.io/kubernetes/pkg/client/unversioned"
+	"k8s.io/kubernetes/pkg/client/restclient"
 	"k8s.io/kubernetes/pkg/client/unversioned/clientcmd"
 	clientcmdapi "k8s.io/kubernetes/pkg/client/unversioned/clientcmd/api"
 	"k8s.io/kubernetes/pkg/labels"
@@ -29,6 +30,9 @@ type Kubernetes struct {
 	Zones         []string
 	Proxy         proxy.Proxy // Proxy for looking up names during the resolution process
 	APIEndpoint   string
+	APICertAuth   string
+	APIClientCert string
+	APIClientKey  string
 	APIConn       *dnsController
 	ResyncPeriod  time.Duration
 	NameTemplate  *nametemplate.NameTemplate
@@ -37,23 +41,41 @@ type Kubernetes struct {
 	Selector      *labels.Selector
 }
 
-// InitKubeCache initializes a new Kubernetes cache.
-// TODO(miek): is this correct?
-func (k *Kubernetes) InitKubeCache() error {
+func (k *Kubernetes) getClientConfig() (*restclient.Config, error) {
 	// For a custom api server or running outside a k8s cluster
 	// set URL in env.KUBERNETES_MASTER or set endpoint in Corefile
 	loadingRules := clientcmd.NewDefaultClientConfigLoadingRules()
 	overrides := &clientcmd.ConfigOverrides{}
+	clusterinfo := clientcmdapi.Cluster{}
+	authinfo := clientcmdapi.AuthInfo{}
 	if len(k.APIEndpoint) > 0 {
-		overrides.ClusterInfo = clientcmdapi.Cluster{Server: k.APIEndpoint}
+		clusterinfo.Server = k.APIEndpoint
 	}
+	if len(k.APICertAuth) > 0 {
+		clusterinfo.CertificateAuthority = k.APICertAuth
+	}
+	if len(k.APIClientCert) > 0 {
+		authinfo.ClientCertificate = k.APIClientCert
+	}
+	if len(k.APIClientKey) > 0 {
+		authinfo.ClientKey = k.APIClientKey
+	}
+	overrides.ClusterInfo = clusterinfo
+	overrides.AuthInfo = authinfo
 	clientConfig := clientcmd.NewNonInteractiveDeferredLoadingClientConfig(loadingRules, overrides)
-	config, err := clientConfig.ClientConfig()
+	return clientConfig.ClientConfig()
+}
+
+// InitKubeCache initializes a new Kubernetes cache.
+// TODO(miek): is this correct?
+func (k *Kubernetes) InitKubeCache() error {
+
+	config, err := k.getClientConfig()
 	if err != nil {
 		return err
 	}
-	kubeClient, err := unversionedclient.New(config)
 
+	kubeClient, err := unversionedclient.New(config)
 	if err != nil {
 		log.Printf("[ERROR] Failed to create kubernetes notification controller: %v", err)
 		return err

middleware/kubernetes/setup.go

@@ -75,7 +75,7 @@ func kubernetesParse(c *caddy.Controller) (*Kubernetes, error) {
 				switch c.Val() {
 				case "template":
 					args := c.RemainingArgs()
-					if len(args) != 0 {
+					if len(args) > 0 {
 						template := strings.Join(args, "")
 						err := k8s.NameTemplate.SetTemplate(template)
 						if err != nil {
@@ -86,21 +86,28 @@ func kubernetesParse(c *caddy.Controller) (*Kubernetes, error) {
 					return nil, c.ArgErr()
 				case "namespaces":
 					args := c.RemainingArgs()
-					if len(args) != 0 {
+					if len(args) > 0 {
 						k8s.Namespaces = append(k8s.Namespaces, args...)
 						continue
 					}
 					return nil, c.ArgErr()
 				case "endpoint":
 					args := c.RemainingArgs()
-					if len(args) != 0 {
+					if len(args) > 0 {
 						k8s.APIEndpoint = args[0]
 						continue
 					}
 					return nil, c.ArgErr()
+				case "tls": // cert key cacertfile
+					args := c.RemainingArgs()
+					if len(args) == 3 {
+						k8s.APIClientCert, k8s.APIClientKey, k8s.APICertAuth = args[0], args[1], args[2]
+						continue
+					}
+					return nil, c.ArgErr()
 				case "resyncperiod":
 					args := c.RemainingArgs()
-					if len(args) != 0 {
+					if len(args) > 0 {
 						rp, err := time.ParseDuration(args[0])
 						if err != nil {
 							return nil, fmt.Errorf("Unable to parse resync duration value. Value provided was '%v'. Example valid values: '15s', '5m', '1h'. Error was: %v", args[0], err)
@@ -111,7 +118,7 @@ func kubernetesParse(c *caddy.Controller) (*Kubernetes, error) {
 					return nil, c.ArgErr()
 				case "labels":
 					args := c.RemainingArgs()
-					if len(args) != 0 {
+					if len(args) > 0 {
 						labelSelectorString := strings.Join(args, " ")
 						ls, err := unversionedapi.ParseToLabelSelector(labelSelectorString)
 						if err != nil {