Check Kubernetes version.

This commit checks whether the Kubernetes version is >= v1.8
It fails the installation otherwise.

Testing Done:

* Verified the version check succeeds for v1.8

* Verified that the version check fails for v1.7

Refs argoproj#473

Gopkg.toml

@@ -25,3 +25,7 @@
 [[constraint]]
  name = "github.com/minio/minio-go"
  version = "3.0.2"
+
+[[constraint]]
+ branch = "master"
+ name = "github.com/hashicorp/go-version"

cmd/argo/commands/install.go

@@ -9,6 +9,7 @@ import (
  "github.com/argoproj/argo/workflow/common"
  "github.com/argoproj/argo/workflow/controller"
  "github.com/ghodss/yaml"
+ goversion "github.com/hashicorp/go-version"
  log "github.com/sirupsen/logrus"
  "github.com/spf13/cobra"
  appsv1beta2 "k8s.io/api/apps/v1beta2"
@@ -155,11 +156,37 @@ func setupArgoRoleBinding(clientset *kubernetes.Clientset) error {
 
  return nil
 }
+func kubernetesVersionCheck(clientset *kubernetes.Clientset) {
+ // Check if the Kubernetes version is >= 1.8
+ versionInfo, err := clientset.ServerVersion()
+ if err != nil {
+ log.Fatalf("Failed to get Kubernetes version: %v", err)
+ }
+
+ serverVersion, err := goversion.NewVersion(versionInfo.String())
+ if err != nil {
+ log.Fatalf("Failed to create version: %v", err)
+ }
+
+ minVersion, err := goversion.NewVersion("1.8")
+ if err != nil {
+ log.Fatalf("Failed to create minimum version: %v", err)
+ }
+
+ if serverVersion.LessThan(minVersion) {
+ log.Fatalf("Server version %v < %v. Installation won't proceed...\n", serverVersion, minVersion)
+ }
+
+ fmt.Printf("Proceeding with Kubernetes version %v\n", serverVersion)
+}
 
 func install(cmd *cobra.Command, args []string) {
  fmt.Printf("Installing into namespace '%s'\n", installArgs.namespace)
 
  clientset = initKubeClient()
+
+ kubernetesVersionCheck(clientset)
+
  clusterAdminFound, err := getClusterAdmin(clientset)
  if err != nil {
  fmt.Printf("%s\n", err)