added k8s server version check (#404)

cli/kubernetes/provider.go

@@ -7,6 +7,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"github.com/up9inc/mizu/shared/semver"
 	"k8s.io/apimachinery/pkg/version"
 	"net/url"
 	"path/filepath"
@@ -83,6 +84,10 @@ func NewProvider(kubeConfigPath string) (*Provider, error) {
 		return nil, err
 	}
 
+	if err := validateKubernetesVersion(clientSet); err != nil {
+		return nil, err
+	}
+
 	return &Provider{
 		clientSet:        clientSet,
 		kubernetesConfig: kubernetesConfig,
@@ -761,3 +766,19 @@ func validateNotProxy(kubernetesConfig clientcmd.ClientConfig, restClientConfig
 
 	return nil
 }
+
+func validateKubernetesVersion(clientSet *kubernetes.Clientset) error {
+	serverVersion, err := clientSet.ServerVersion()
+	if err != nil {
+		logger.Log.Debugf("error while getting kubernetes server version, err: %v", err)
+		return nil
+	}
+
+	serverVersionSemVer := semver.SemVersion(serverVersion.GitVersion)
+	minKubernetesServerVersionSemVer := semver.SemVersion(mizu.MinKubernetesServerVersion)
+	if minKubernetesServerVersionSemVer.GreaterThan(serverVersionSemVer) {
+		return fmt.Errorf("kubernetes server version %v is not supported, supporting only kubernetes server version of %v or higher", serverVersion.GitVersion, mizu.MinKubernetesServerVersion)
+	}
+
+	return nil
+}

cli/mizu/consts.go

@@ -25,6 +25,7 @@ const (
 	TapperDaemonSetName        = MizuResourcesPrefix + "tapper-daemon-set"
 	TapperPodName              = MizuResourcesPrefix + "tapper"
 	ConfigMapName              = MizuResourcesPrefix + "policy"
+	MinKubernetesServerVersion = "1.16.0"
 )
 
 func GetMizuFolderPath() string {