add version api (#2127)

add cluster validation api

pkg/kapis/version/register.go

@@ -0,0 +1,35 @@
+package version
+
+import (
+	"github.com/emicklei/go-restful"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/client-go/discovery"
+	"k8s.io/klog"
+	"kubesphere.io/kubesphere/pkg/apiserver/runtime"
+	"kubesphere.io/kubesphere/pkg/version"
+)
+
+func AddToContainer(container *restful.Container, k8sDiscovery discovery.DiscoveryInterface) error {
+	webservice := runtime.NewWebService(schema.GroupVersion{})
+
+	webservice.Route(webservice.GET("/version").
+		To(func(request *restful.Request, response *restful.Response) {
+			ksVersion := version.Get()
+
+			if k8sDiscovery != nil {
+				k8sVersion, err := k8sDiscovery.ServerVersion()
+				if err == nil {
+					ksVersion.Kubernetes = k8sVersion
+				} else {
+					klog.Errorf("Failed to get kubernetes version, error %v", err)
+				}
+			}
+
+			response.WriteAsJson(ksVersion)
+		})).
+		Doc("KubeSphere version")
+
+	container.Add(webservice)
+
+	return nil
+}