diff --git a/cmd/config/ext/ext.go b/cmd/config/ext/ext.go
new file mode 100644
index 000000000..d9d64f2c1
--- /dev/null
+++ b/cmd/config/ext/ext.go
@@ -0,0 +1,12 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package ext
+
+import "path/filepath"
+
+// GetOpenAPIFile returns the path to the file containing supplementary OpenAPI definitions.
+// Maybe be overridden to configure which file to read OpenAPI definitions from.
+var GetOpenAPIFile = func(args []string) (string, error) {
+	return filepath.Join(args[0], "kustomization"), nil
+}
diff --git a/cmd/config/internal/commands/cmdcreatesetter.go b/cmd/config/internal/commands/cmdcreatesetter.go
index 54725c54c..9bcbe03d0 100644
--- a/cmd/config/internal/commands/cmdcreatesetter.go
+++ b/cmd/config/internal/commands/cmdcreatesetter.go
@@ -5,6 +5,7 @@ package commands
 
 import (
 	"github.com/spf13/cobra"
+	"sigs.k8s.io/kustomize/cmd/config/ext"
 	"sigs.k8s.io/kustomize/cmd/config/internal/generateddocs/commands"
 	"sigs.k8s.io/kustomize/kyaml/kio"
 	"sigs.k8s.io/kustomize/kyaml/setters"
@@ -85,7 +86,7 @@ func (r *CreateSetterRunner) preRunE(c *cobra.Command, args []string) error {
 	}
 	if setterVersion == "v2" {
 		var err error
-		r.OpenAPIFile, err = GetOpenAPIFile(args)
+		r.OpenAPIFile, err = ext.GetOpenAPIFile(args)
 		r.CreateSetter.Description = r.Set.SetPartialField.Description
 		r.CreateSetter.SetBy = r.Set.SetPartialField.SetBy
 		if err != nil {
diff --git a/cmd/config/internal/commands/cmdcreatesetter_test.go b/cmd/config/internal/commands/cmdcreatesetter_test.go
index 00cd1bb02..ac4141cd0 100644
--- a/cmd/config/internal/commands/cmdcreatesetter_test.go
+++ b/cmd/config/internal/commands/cmdcreatesetter_test.go
@@ -11,6 +11,7 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"sigs.k8s.io/kustomize/cmd/config/ext"
 	"sigs.k8s.io/kustomize/cmd/config/internal/commands"
 	"sigs.k8s.io/kustomize/kyaml/openapi"
 )
@@ -77,7 +78,9 @@ kind: Example
 			if !assert.NoError(t, err) {
 				t.FailNow()
 			}
-			commands.GetOpenAPIFile = func(args []string) (s string, err error) {
+			old := ext.GetOpenAPIFile
+			defer func() { ext.GetOpenAPIFile = old }()
+			ext.GetOpenAPIFile = func(args []string) (s string, err error) {
 				return f.Name(), nil
 			}
 
diff --git a/cmd/config/internal/commands/cmdcreatesubstitution.go b/cmd/config/internal/commands/cmdcreatesubstitution.go
index c7d5e63c6..66bbba070 100644
--- a/cmd/config/internal/commands/cmdcreatesubstitution.go
+++ b/cmd/config/internal/commands/cmdcreatesubstitution.go
@@ -7,6 +7,7 @@ import (
 	"strings"
 
 	"github.com/spf13/cobra"
+	"sigs.k8s.io/kustomize/cmd/config/ext"
 	"sigs.k8s.io/kustomize/kyaml/errors"
 	"sigs.k8s.io/kustomize/kyaml/setters2"
 	"sigs.k8s.io/kustomize/kyaml/setters2/settersutil"
@@ -58,7 +59,7 @@ func (r *CreateSubstitutionRunner) preRunE(c *cobra.Command, args []string) erro
 		return err
 	}
 
-	r.OpenAPIFile, err = GetOpenAPIFile(args)
+	r.OpenAPIFile, err = ext.GetOpenAPIFile(args)
 	if err != nil {
 		return err
 	}
diff --git a/cmd/config/internal/commands/cmdcreatesubstitution_test.go b/cmd/config/internal/commands/cmdcreatesubstitution_test.go
index 73bd77fd9..86e80cbe9 100644
--- a/cmd/config/internal/commands/cmdcreatesubstitution_test.go
+++ b/cmd/config/internal/commands/cmdcreatesubstitution_test.go
@@ -11,6 +11,7 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"sigs.k8s.io/kustomize/cmd/config/ext"
 	"sigs.k8s.io/kustomize/cmd/config/internal/commands"
 	"sigs.k8s.io/kustomize/kyaml/openapi"
 )
@@ -120,7 +121,9 @@ spec:
 			if !assert.NoError(t, err) {
 				t.FailNow()
 			}
-			commands.GetOpenAPIFile = func(args []string) (s string, err error) {
+			old := ext.GetOpenAPIFile
+			defer func() { ext.GetOpenAPIFile = old }()
+			ext.GetOpenAPIFile = func(args []string) (s string, err error) {
 				return f.Name(), nil
 			}
 
diff --git a/cmd/config/internal/commands/cmdlistsetters.go b/cmd/config/internal/commands/cmdlistsetters.go
index c4a8e29b5..e51f84fff 100644
--- a/cmd/config/internal/commands/cmdlistsetters.go
+++ b/cmd/config/internal/commands/cmdlistsetters.go
@@ -10,6 +10,7 @@ import (
 
 	"github.com/olekukonko/tablewriter"
 	"github.com/spf13/cobra"
+	"sigs.k8s.io/kustomize/cmd/config/ext"
 	"sigs.k8s.io/kustomize/cmd/config/internal/generateddocs/commands"
 	"sigs.k8s.io/kustomize/kyaml/setters"
 	"sigs.k8s.io/kustomize/kyaml/setters2"
@@ -55,7 +56,7 @@ func (r *ListSettersRunner) preRunE(c *cobra.Command, args []string) error {
 func (r *ListSettersRunner) runE(c *cobra.Command, args []string) error {
 	if setterVersion == "v2" {
 		// use setters v2
-		path, err := GetOpenAPIFile(args)
+		path, err := ext.GetOpenAPIFile(args)
 		if err != nil {
 			return err
 		}
diff --git a/cmd/config/internal/commands/cmdlistsetters_test.go b/cmd/config/internal/commands/cmdlistsetters_test.go
index 017ba6ce7..dbd97a2b4 100644
--- a/cmd/config/internal/commands/cmdlistsetters_test.go
+++ b/cmd/config/internal/commands/cmdlistsetters_test.go
@@ -10,6 +10,7 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"sigs.k8s.io/kustomize/cmd/config/ext"
 	"sigs.k8s.io/kustomize/cmd/config/internal/commands"
 	"sigs.k8s.io/kustomize/kyaml/openapi"
 )
@@ -261,7 +262,9 @@ spec:
 				t.FailNow()
 			}
 			defer os.Remove(f.Name())
-			commands.GetOpenAPIFile = func(args []string) (s string, err error) {
+			old := ext.GetOpenAPIFile
+			defer func() { ext.GetOpenAPIFile = old }()
+			ext.GetOpenAPIFile = func(args []string) (s string, err error) {
 				err = ioutil.WriteFile(f.Name(), []byte(test.openapi), 0600)
 				if !assert.NoError(t, err) {
 					t.FailNow()
diff --git a/cmd/config/internal/commands/cmdset.go b/cmd/config/internal/commands/cmdset.go
index a646fd1de..d549a616b 100644
--- a/cmd/config/internal/commands/cmdset.go
+++ b/cmd/config/internal/commands/cmdset.go
@@ -6,10 +6,10 @@ package commands
 import (
 	"fmt"
 	"os"
-	"path/filepath"
 
 	"github.com/olekukonko/tablewriter"
 	"github.com/spf13/cobra"
+	"sigs.k8s.io/kustomize/cmd/config/ext"
 	"sigs.k8s.io/kustomize/cmd/config/internal/generateddocs/commands"
 	"sigs.k8s.io/kustomize/kyaml/kio"
 	"sigs.k8s.io/kustomize/kyaml/setters"
@@ -43,10 +43,6 @@ func NewSetRunner(parent string) *SetRunner {
 
 var setterVersion string
 
-var GetOpenAPIFile = func(args []string) (string, error) {
-	return filepath.Join(args[0], "kustomization"), nil
-}
-
 func SetCommand(parent string) *cobra.Command {
 	return NewSetRunner(parent).Command
 }
@@ -100,7 +96,7 @@ func (r *SetRunner) preRunE(c *cobra.Command, args []string) error {
 		r.Set.Value = args[2]
 		r.Set.Description = r.Perform.Description
 		r.Set.SetBy = r.Perform.SetBy
-		r.OpenAPIFile, err = GetOpenAPIFile(args)
+		r.OpenAPIFile, err = ext.GetOpenAPIFile(args)
 		if err != nil {
 			return err
 		}
diff --git a/cmd/config/internal/commands/cmdset_test.go b/cmd/config/internal/commands/cmdset_test.go
index 97b45fba5..f617660b7 100644
--- a/cmd/config/internal/commands/cmdset_test.go
+++ b/cmd/config/internal/commands/cmdset_test.go
@@ -11,6 +11,7 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"sigs.k8s.io/kustomize/cmd/config/ext"
 	"sigs.k8s.io/kustomize/cmd/config/internal/commands"
 	"sigs.k8s.io/kustomize/kyaml/openapi"
 )
@@ -224,7 +225,9 @@ spec:
 			if !assert.NoError(t, err) {
 				t.FailNow()
 			}
-			commands.GetOpenAPIFile = func(args []string) (s string, err error) {
+			old := ext.GetOpenAPIFile
+			defer func() { ext.GetOpenAPIFile = old }()
+			ext.GetOpenAPIFile = func(args []string) (s string, err error) {
 				return f.Name(), nil
 			}