add varialber reference support

pkg/transformers/refvars.go

@@ -0,0 +1,83 @@
+package transformers
+
+import (
+	"fmt"
+
+	"github.com/kubernetes-sigs/kustomize/pkg/expansion"
+	"github.com/kubernetes-sigs/kustomize/pkg/resmap"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+)
+
+type refvarTransformer struct {
+	pathConfigs []PathConfig
+	vars        map[string]string
+}
+
+func NewRefVarTransformer(vars map[string]string) (Transformer, error) {
+	return &refvarTransformer{
+		vars: vars,
+		pathConfigs: []PathConfig{
+			{
+				GroupVersionKind: &schema.GroupVersionKind{Kind: "StatefulSet"},
+				Path:             []string{"spec", "template", "spec", "initContainers", "command"},
+			},
+			{
+				GroupVersionKind: &schema.GroupVersionKind{Kind: "StatefulSet"},
+				Path:             []string{"spec", "template", "spec", "containers", "command"},
+			},
+			{
+				GroupVersionKind: &schema.GroupVersionKind{Kind: "Job"},
+				Path:             []string{"spec", "template", "spec", "containers", "command"},
+			},
+		},
+	}, nil
+}
+
+func (rv *refvarTransformer) Transform(resources resmap.ResMap) error {
+	// Determine the final values of variables:
+	//
+	// 1.  Determine the final value of each variable:
+	//     a.  If the variable's Value is set, expand the `$(var)` references to other
+	//         variables in the .Value field; the sources of variables are the declared
+	//         variables of the container and the service environment variables
+	//     b.  If a source is defined for an environment variable, resolve the source
+	// 2.  Create the container's environment in the order variables are declared
+	// 3.  Add remaining service environment vars
+
+	for GVKn := range resources {
+		obj := resources[GVKn].Unstruct()
+		objMap := obj.UnstructuredContent()
+		for _, pc := range rv.pathConfigs {
+			if !selectByGVK(GVKn.Gvk(), pc.GroupVersionKind) {
+				continue
+			}
+			err := mutateField(objMap, pc.Path, false, func(in interface{}) (interface{}, error) {
+				var (
+					mappingFunc = expansion.MappingFuncFor(rv.vars)
+				)
+				switch vt := in.(type) {
+				case []interface{}:
+					var xs []string
+					for _, a := range in.([]interface{}) {
+						xs = append(xs, expansion.Expand(a.(string), mappingFunc))
+					}
+					return xs, nil
+				case interface{}:
+					s, ok := in.(string)
+					if !ok {
+						return nil, fmt.Errorf("%#v is expectd to be %T", in, s)
+					}
+					runtimeVal := expansion.Expand(s, mappingFunc)
+					return runtimeVal, nil
+				default:
+					return "", fmt.Errorf("invalid type encountered %T", vt)
+				}
+				return "", fmt.Errorf("invalid type encountered")
+			})
+			if err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}