feat(helm): Support setting --kube-version

Signed-off-by: Thomas Dy <thatsmydoing@gmail.com>

cmd/helm/template.go

@@ -52,6 +52,7 @@ func newTemplateCmd(cfg *action.Configuration, out io.Writer) *cobra.Command {
 	var skipTests bool
 	client := action.NewInstall(cfg)
 	valueOpts := &values.Options{}
+	var kubeVersion string
 	var extraAPIs []string
 	var showFiles []string
 
@@ -64,6 +65,14 @@ func newTemplateCmd(cfg *action.Configuration, out io.Writer) *cobra.Command {
 			return compInstall(args, toComplete, client)
 		},
 		RunE: func(_ *cobra.Command, args []string) error {
+			if kubeVersion != "" {
+				parsedKubeVersion, err := chartutil.ParseKubeVersion(kubeVersion)
+				if err != nil {
+					return fmt.Errorf("invalid kube version '%s': %s", kubeVersion, err)
+				}
+				client.KubeVersion = parsedKubeVersion
+			}
+
 			client.DryRun = true
 			client.ReleaseName = "RELEASE-NAME"
 			client.Replace = true // Skip the name check
@@ -171,6 +180,7 @@ func newTemplateCmd(cfg *action.Configuration, out io.Writer) *cobra.Command {
 	f.BoolVar(&includeCrds, "include-crds", false, "include CRDs in the templated output")
 	f.BoolVar(&skipTests, "skip-tests", false, "skip tests from templated output")
 	f.BoolVar(&client.IsUpgrade, "is-upgrade", false, "set .Release.IsUpgrade instead of .Release.IsInstall")
+	f.StringVar(&kubeVersion, "kube-version", "", "Kubernetes version used for Capabilities.KubeVersion")
 	f.StringArrayVarP(&extraAPIs, "api-versions", "a", []string{}, "Kubernetes api versions used for Capabilities.APIVersions")
 	f.BoolVar(&client.UseReleaseName, "release-name", false, "use release name in the output-dir path.")
 	bindPostRenderFlag(cmd, &client.PostRenderer)

pkg/action/install.go

@@ -92,8 +92,10 @@ type Install struct {
 	SubNotes                 bool
 	DisableOpenAPIValidation bool
 	IncludeCRDs              bool
+	// KubeVersion allows specifying a custom kubernetes version to use and
 	// APIVersions allows a manual set of supported API Versions to be passed
 	// (for things like templating). These are ignored if ClientOnly is false
+	KubeVersion *chartutil.KubeVersion
 	APIVersions chartutil.VersionSet
 	// Used by helm template to render charts with .Release.IsUpgrade. Ignored if Dry-Run is false
 	IsUpgrade bool
@@ -197,6 +199,9 @@ func (i *Install) Run(chrt *chart.Chart, vals map[string]interface{}) (*release.
 		// Add mock objects in here so it doesn't use Kube API server
 		// NOTE(bacongobbler): used for `helm template`
 		i.cfg.Capabilities = chartutil.DefaultCapabilities
+		if i.KubeVersion != nil {
+			i.cfg.Capabilities.KubeVersion = *i.KubeVersion
+		}
 		i.cfg.Capabilities.APIVersions = append(i.cfg.Capabilities.APIVersions, i.APIVersions...)
 		i.cfg.KubeClient = &kubefake.PrintingKubeClient{Out: ioutil.Discard}
 

pkg/chartutil/capabilities.go

@@ -19,6 +19,7 @@ import (
 	"fmt"
 	"strconv"
 
+	"github.com/Masterminds/semver/v3"
 	"k8s.io/client-go/kubernetes/scheme"
 
 	apiextensionsv1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
@@ -73,6 +74,19 @@ func (kv *KubeVersion) String() string { return kv.Version }
 // Deprecated: use KubeVersion.Version.
 func (kv *KubeVersion) GitVersion() string { return kv.Version }
 
+// ParseKubeVersion parses kubernetes version from string
+func ParseKubeVersion(version string) (*KubeVersion, error) {
+	sv, err := semver.NewVersion(version)
+	if err != nil {
+		return nil, err
+	}
+	return &KubeVersion{
+		Version: sv.Original(),
+		Major:   strconv.FormatUint(sv.Major(), 10),
+		Minor:   strconv.FormatUint(sv.Minor(), 10),
+	}, nil
+}
+
 // VersionSet is a set of Kubernetes API versions.
 type VersionSet []string