add replacements field

pkg/types/kustomization.go

@@ -79,6 +79,11 @@ type Kustomization struct {
 	// value of the specified field has been determined.
 	Vars []Var `json:"vars,omitempty" yaml:"vars,omitempty"`
 
+	// Replacements defines substitutions including source and destinations.
+	// It is used to inject a field from one Kubernetes resource into another Kubernetes
+	// resources. It can also inject a literal string into a Kubernetes resources.
+	Replacements []Replacement `json:"replacements,omitempty" yaml:"replacements,omitempty"`
+
 	//
 	// Operands - what kustomize operates on.
 	//

pkg/types/replacement.go

@@ -0,0 +1,27 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package types
+
+// Replacement defines how to perform a substitution
+// where it is from and where it is to.
+type Replacement struct {
+	From *From `json:"from" yaml:"from"`
+	To   *To   `json:"To" yaml:"to"`
+}
+
+// From defines where a substitution is from
+// It can from two different kinds of sources
+//  - from a field of one resource
+//  - from a string
+type From struct {
+	ObjRef   *Target `json:"objref,omitempty" yaml:"objref,omitempty"`
+	FieldRef string  `json:"fieldref,omitempty" yaml:"fiedldref,omitempty"`
+	Value    string  `json:"value,omitempty" yaml:"value,omitempty"`
+}
+
+// To defines where a substitution is to.
+type To struct {
+	Target    *Selector `json:"target,omitempty" yaml:"target,omitempty"`
+	FieldRefs []string  `json:"fieldrefs,omitempty" yaml:"fieldrefs,omitempty"`
+}