feat(helm): add --kube-version flag to helm template

This commit adds --kube-version flag to helm template. It allows you to
override the Kubernetes version used as Capabilities.KubeVersion.Major/Minor (e.g. 1.7).

cmd/helm/template.go

@@ -26,6 +26,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/Masterminds/semver"
 	"github.com/spf13/cobra"
 	"k8s.io/helm/pkg/chartutil"
 	"k8s.io/helm/pkg/engine"
@@ -62,6 +63,7 @@ type templateCmd struct {
 	showNotes    bool
 	releaseName  string
 	renderFiles  []string
+	kubeVersion  string
 }
 
 func newTemplateCmd(out io.Writer) *cobra.Command {
@@ -85,6 +87,7 @@ func newTemplateCmd(out io.Writer) *cobra.Command {
 	f.StringVar(&t.namespace, "namespace", "", "namespace to install the release into")
 	f.StringArrayVar(&t.values, "set", []string{}, "set values on the command line (can specify multiple or separate values with commas: key1=val1,key2=val2)")
 	f.StringVar(&t.nameTemplate, "name-template", "", "specify template used to name the release")
+	f.StringVar(&t.kubeVersion, "kube-version", "", "override the Kubernetes version used as Capabilities.KubeVersion.Major/Minor (e.g. 1.7)")
 
 	return cmd
 }
@@ -177,6 +180,16 @@ func (t *templateCmd) run(cmd *cobra.Command, args []string) error {
 		KubeVersion:   chartutil.DefaultKubeVersion,
 		TillerVersion: tversion.GetVersionProto(),
 	}
+	// If --kube-versionis set, try to parse it as SemVer, and override the
+	// kubernetes version
+	if t.kubeVersion != "" {
+		kv, err := semver.NewVersion(t.kubeVersion)
+		if err != nil {
+			return fmt.Errorf("could not parse a kubernetes version: %v", err)
+		}
+		caps.KubeVersion.Major = fmt.Sprint(kv.Major())
+		caps.KubeVersion.Minor = fmt.Sprint(kv.Minor())
+	}
 	vals, err := chartutil.ToRenderValuesCaps(c, config, options, caps)
 	if err != nil {
 		return err

cmd/helm/template_test.go

@@ -104,6 +104,13 @@ func TestTemplateCmd(t *testing.T) {
 			expectKey:   "subchart1/templates/service.yaml",
 			expectValue: "release-name: \"foobar-YWJj-baz\"",
 		},
+		{
+			name:        "check_kube_version",
+			desc:        "verify --kube-version overrides the kubernetes version",
+			args:        []string{chartPath, "--kube-version", "1.6"},
+			expectKey:   "subchart1/templates/service.yaml",
+			expectValue: "kube-version/major: \"1\"\n    kube-version/minor: \"6\"",
+		},
 	}
 
 	var buf bytes.Buffer

docs/helm/helm_template.md

@@ -26,6 +26,7 @@ helm template [flags] CHART
 
 ```
   -x, --execute stringArray    only execute the given templates
+      --kube-version string    override the Kubernetes version used as Capabilities.KubeVersion.Major/Minor (e.g. 1.7)
   -n, --name string            release name (default "RELEASE-NAME")
       --name-template string   specify template used to name the release
       --namespace string       namespace to install the release into
@@ -47,4 +48,4 @@ helm template [flags] CHART
 ### SEE ALSO
 * [helm](helm.md)	 - The Helm package manager for Kubernetes.
 
-###### Auto generated by spf13/cobra on 24-Aug-2017
+###### Auto generated by spf13/cobra on 11-Sep-2017

pkg/chartutil/testdata/subpop/charts/subchart1/templates/service.yaml

@@ -6,6 +6,8 @@ metadata:
     chart: "{{ .Chart.Name }}-{{ .Chart.Version }}"
     namespace: "{{ .Release.Namespace }}"
     release-name: "{{ .Release.Name }}"
+    kube-version/major: "{{ .Capabilities.KubeVersion.Major }}"
+    kube-version/minor: "{{ .Capabilities.KubeVersion.Minor }}"
 spec:
   type: {{ .Values.service.type }}
   ports: