feat(helm): add support for helm capabilities (#48)

Capabilities can be defined in env-data.ytt.yaml.
Capabilities are passed to helm template.

Fixes #31

internal/myks/application.go

@@ -3,11 +3,12 @@ package myks
 import (
 	"errors"
 	"fmt"
-	"github.com/rs/zerolog/log"
-	yaml "gopkg.in/yaml.v3"
 	"io"
 	"os"
 	"path/filepath"
+
+	"github.com/rs/zerolog/log"
+	yaml "gopkg.in/yaml.v3"
 )
 
 const (
@@ -35,13 +36,16 @@ type Application struct {
 }
 
 type HelmConfig struct {
-	Namespace   string `yaml:"namespace"`
-	KubeVersion string `yaml:"kubeVersion"`
-	IncludeCRDs bool   `yaml:"includeCRDs"`
+	Namespace    string   `yaml:"namespace"`
+	KubeVersion  string   `yaml:"kubeVersion"`
+	IncludeCRDs  bool     `yaml:"includeCRDs"`
+	Capabilities []string `yaml:"capabilities"`
 }
 
-var ErrNoVendirConfig = errors.New("no vendir config found")
-var ApplicationLogFormat = "\033[1m[%s > %s > %s]\033[0m %s"
+var (
+	ErrNoVendirConfig    = errors.New("no vendir config found")
+	ApplicationLogFormat = "\033[1m[%s > %s > %s]\033[0m %s"
+)
 
 func NewApplication(e *Environment, name string, prototypeName string) (*Application, error) {
 	if prototypeName == "" {

internal/myks/assets/data-schema.ytt.yaml

@@ -31,6 +31,10 @@ helm:
   #! Used by myks.
   #! If defined, passed as a value of `--namespace` for `helm template`.
   namespace: ""
+  #! Used by myks.
+  #! If defined, passed as `--api-version` for `helm-template`.
+  capabilities:
+  - "" #! e.g. "monitoring.coreos.com/v1"
 #! Myks configuration and runtime data.
 myks:
   applicationDataFileName: ""

internal/myks/render_helm.go

@@ -57,6 +57,9 @@ func (h *Helm) Render(_ string) (string, error) {
 		commonHelmArgs = append(commonHelmArgs, "--include-crds")
 	}
 
+	for _, capa := range helmConfig.Capabilities {
+		commonHelmArgs = append(commonHelmArgs, "--api-versions", capa)
+	}
 	var outputs []string
 
 	for _, chartDir := range chartDirs {