Enable use of generators in transformers field

api/internal/plugins/loader/loader.go

@@ -111,7 +111,10 @@ func (l *Loader) LoadTransformer(
 	}
 	t, ok := c.(resmap.Transformer)
 	if !ok {
-		return nil, fmt.Errorf("plugin %s not a transformer", res.OrgId())
+		if g, ok := c.(resmap.Generator); ok {
+			return &resmap.TransformerWithProperties{Transformer: &resmap.GeneratorAsTransformer{Generator: g}}, nil
+		}
+		return nil, fmt.Errorf("plugin %s is neither a transformer nor generator", res.OrgId())
 	}
 	return &resmap.TransformerWithProperties{Transformer: t}, nil
 }
@@ -282,4 +285,3 @@ func (l *Loader) loadExecOrGoPlugin(resId resid.ResId) (resmap.Configurable, err
 	}
 	return c, nil
 }
-

api/krusty/generator_as_transformer_test.go

@@ -0,0 +1,36 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package krusty_test
+
+import (
+	"testing"
+
+	kusttest_test "sigs.k8s.io/kustomize/api/testutils/kusttest"
+)
+
+func TestSecretGeneratorAsTransformer(t *testing.T) {
+	th := kusttest_test.MakeHarness(t)
+	th.WriteK("app/base", `
+transformers:
+- |-
+  apiVersion: builtin
+  kind: SecretGenerator
+  metadata:
+    name: foo
+  literals:
+  - foo=bar
+  options:
+    disableNameSuffixHash: true
+`)
+	m := th.Run("app/base", th.MakeDefaultOptions())
+	th.AssertActualEqualsExpected(m, `
+apiVersion: v1
+data:
+  foo: YmFy
+kind: Secret
+metadata:
+  name: foo
+type: Opaque
+`)
+}

api/resmap/resmap.go

@@ -6,6 +6,8 @@
 package resmap
 
 import (
+	"fmt"
+
 	"sigs.k8s.io/kustomize/api/ifc"
 	"sigs.k8s.io/kustomize/api/resource"
 	"sigs.k8s.io/kustomize/api/types"
@@ -40,6 +42,21 @@ type GeneratorWithProperties struct {
 	Origin *resource.Origin
 }
 
+type GeneratorAsTransformer struct {
+	Generator
+}
+
+func (g *GeneratorAsTransformer) Transform(m ResMap) error {
+	rm, err := g.Generate()
+	if err != nil {
+		return err
+	}
+	if err = m.AppendAll(rm); err != nil {
+		return fmt.Errorf("failed to add generated resources to resmap: %w", err)
+	}
+	return nil
+}
+
 // Something that's configurable accepts an
 // instance of PluginHelpers and a raw config
 // object (YAML in []byte form).