✨ Allow to specify a source from replacements.

This allows getting source information from a file or an orthogonal
kustomization. It removes the need for injecting resources
in the kustomization before doing the replacement and removing
them after.

This can be used with another kustomization, for instance one
decrypting secrets or from a single resource file.

pkg/extras/replacement.go

@@ -4,31 +4,38 @@
 package extras
 
 import (
-	"errors"
 	"fmt"
 	"reflect"
 	"strings"
 
 	"github.com/kaweezle/krmfnbuiltin/pkg/utils"
+	"github.com/pkg/errors"
+	"sigs.k8s.io/kustomize/api/loader"
 	"sigs.k8s.io/kustomize/api/resmap"
 	"sigs.k8s.io/kustomize/api/resource"
 	"sigs.k8s.io/kustomize/api/types"
+	"sigs.k8s.io/kustomize/kyaml/filesys"
 	"sigs.k8s.io/kustomize/kyaml/resid"
 	kyaml_utils "sigs.k8s.io/kustomize/kyaml/utils"
 	"sigs.k8s.io/kustomize/kyaml/yaml"
 )
 
 type extendedFilter struct {
 	Replacements []types.Replacement `json:"replacements,omitempty" yaml:"replacements,omitempty"`
+	sourceNodes  []*yaml.RNode
 }
 
 // Filter replaces values of targets with values from sources
 func (f extendedFilter) Filter(nodes []*yaml.RNode) ([]*yaml.RNode, error) {
+	sourceNodes := f.sourceNodes
+	if sourceNodes == nil {
+		sourceNodes = nodes
+	}
 	for i, r := range f.Replacements {
 		if r.Source == nil || r.Targets == nil {
 			return nil, fmt.Errorf("replacements must specify a source and at least one target")
 		}
-		value, err := getReplacement(nodes, &f.Replacements[i])
+		value, err := getReplacement(sourceNodes, &f.Replacements[i])
 		if err != nil {
 			return nil, err
 		}
@@ -347,6 +354,8 @@ func prevIds(n *yaml.RNode) ([]resid.ResId, error) {
 type ExtendedReplacementTransformerPlugin struct {
 	ReplacementList []types.ReplacementField `json:"replacements,omitempty" yaml:"replacements,omitempty"`
 	Replacements    []types.Replacement      `json:"omitempty" yaml:"omitempty"`
+	Source          string                   `json:"source,omitempty" yaml:"source,omitempty"`
+	h               *resmap.PluginHelpers
 }
 
 // Config configures the plugin
@@ -356,6 +365,7 @@ func (p *ExtendedReplacementTransformerPlugin) Config(
 	if err := yaml.Unmarshal(c, p); err != nil {
 		return err
 	}
+	p.h = h
 
 	for _, r := range p.ReplacementList {
 		if r.Path != "" && (r.Source != nil || len(r.Targets) != 0) {
@@ -395,13 +405,33 @@ func (p *ExtendedReplacementTransformerPlugin) Config(
 			p.Replacements = append(p.Replacements, r.Replacement)
 		}
 	}
+
 	return nil
 }
 
 // Transform performs the configured replacements in the specified resource map
 func (p *ExtendedReplacementTransformerPlugin) Transform(m resmap.ResMap) (err error) {
+
+	var sourceNodes []*yaml.RNode
+	if p.Source != "" {
+		source, err := p.h.ResmapFactory().FromFile(p.h.Loader(), p.Source)
+		if err != nil {
+			if errors.Is(err, loader.ErrHTTP) {
+				return errors.Wrapf(err, "while reading source %s", p.Source)
+			}
+
+			source, err = runKustomizations(filesys.MakeFsOnDisk(), p.Source)
+			if err != nil {
+				return errors.Wrapf(err, "while getting source for replacements %s", p.Source)
+			}
+		}
+
+		sourceNodes = source.ToRNodeSlice()
+	}
+
 	return m.ApplyFilter(extendedFilter{
 		Replacements: p.Replacements,
+		sourceNodes:  sourceNodes,
 	})
 }