Do no require exec/go plugin home to use fn plugins

api/internal/plugins/execplugin/execplugin_test.go

@@ -45,10 +45,12 @@ s/$BAR/bar baz/g
 		})
 
 	pluginConfig.RemoveBuildAnnotations()
-	p := NewExecPlugin(
-		pLdr.AbsolutePluginPath(
-			konfig.DisabledPluginConfig(),
-			pluginConfig.OrgId()))
+	loader := pLdr.NewLoader(konfig.DisabledPluginConfig(), rf)
+	pluginPath, err := loader.AbsolutePluginPath(pluginConfig.OrgId())
+	if err != nil {
+		t.Fatalf("unexpected err: %v", err)
+	}
+	p := NewExecPlugin(pluginPath)
 	// Not checking to see if the plugin is executable,
 	// because this test does not run it.
 	// This tests only covers sending configuration

api/internal/plugins/loader/loader.go

@@ -13,6 +13,7 @@ import (
 	"strings"
 
 	"github.com/pkg/errors"
+	"sigs.k8s.io/kustomize/api/filesys"
 	"sigs.k8s.io/kustomize/api/ifc"
 	"sigs.k8s.io/kustomize/api/internal/plugins/builtinhelpers"
 	"sigs.k8s.io/kustomize/api/internal/plugins/execplugin"
@@ -29,6 +30,10 @@ import (
 type Loader struct {
 	pc *types.PluginConfig
 	rf *resmap.Factory
+
+	// absolutePluginHome caches the location of a valid plugin root directory.
+	// It should only be set once the directory's existence has been confirmed.
+	absolutePluginHome string
 }
 
 func NewLoader(
@@ -95,13 +100,47 @@ func relativePluginPath(id resid.ResId) string {
 		strings.ToLower(id.Kind))
 }
 
-func AbsolutePluginPath(pc *types.PluginConfig, id resid.ResId) string {
-	return filepath.Join(
-		pc.AbsPluginHome, relativePluginPath(id), id.Kind)
+func (l *Loader) AbsolutePluginPath(id resid.ResId) (string, error) {
+	pluginHome, err := l.absPluginHome()
+	if err != nil {
+		return "", err
+	}
+	return filepath.Join(pluginHome, relativePluginPath(id), id.Kind), nil
 }
 
-func (l *Loader) absolutePluginPath(id resid.ResId) string {
-	return AbsolutePluginPath(l.pc, id)
+// absPluginHome is the home of kustomize Exec and Go plugins.
+// Kustomize plugin configuration files are k8s-style objects
+// containing the fields 'apiVersion' and 'kind', e.g.
+//   apiVersion: apps/v1
+//   kind: Deployment
+// kustomize reads plugin configuration data from a file path
+// specified in the 'generators:' or 'transformers:' field of a
+// kustomization file.  For Exec and Go plugins, kustomize
+// uses this data to both locate the plugin and configure it.
+// Each Exec or Go plugin (its code, its tests, its supporting data
+// files, etc.) must be housed in its own directory at
+//   ${absPluginHome}/${pluginApiVersion}/LOWERCASE(${pluginKind})
+// where
+//   - ${absPluginHome} is an absolute path, defined below.
+//   - ${pluginApiVersion} is taken from the plugin config file.
+//   - ${pluginKind} is taken from the plugin config file.
+func (l *Loader) absPluginHome() (string, error) {
+	// External plugins are disabled--return the dummy plugin root.
+	if l.pc.PluginRestrictions != types.PluginRestrictionsNone {
+		return konfig.NoPluginHomeSentinal, nil
+	}
+	// We've already determined plugin home--use the cached value.
+	if l.absolutePluginHome != "" {
+		return l.absolutePluginHome, nil
+	}
+
+	// Check default locations for a valid plugin root, and cache it if found.
+	dir, err := konfig.DefaultAbsPluginHome(filesys.MakeFsOnDisk())
+	if err != nil {
+		return "", err
+	}
+	l.absolutePluginHome = dir
+	return l.absolutePluginHome, nil
 }
 
 func isBuiltinPlugin(res *resource.Resource) bool {
@@ -176,10 +215,13 @@ func (l *Loader) loadPlugin(res *resource.Resource) (resmap.Configurable, error)
 }
 
 func (l *Loader) loadExecOrGoPlugin(resId resid.ResId) (resmap.Configurable, error) {
+	absPluginPath, err := l.AbsolutePluginPath(resId)
+	if err != nil {
+		return nil, err
+	}
 	// First try to load the plugin as an executable.
-	p := execplugin.NewExecPlugin(l.absolutePluginPath(resId))
-	err := p.ErrIfNotExecutable()
-	if err == nil {
+	p := execplugin.NewExecPlugin(absPluginPath)
+	if err = p.ErrIfNotExecutable(); err == nil {
 		return p, nil
 	}
 	if !os.IsNotExist(err) {
@@ -193,7 +235,7 @@ func (l *Loader) loadExecOrGoPlugin(resId resid.ResId) (resmap.Configurable, err
 		return nil, err
 	}
 	// Failing the above, try loading it as a Go plugin.
-	c, err := l.loadGoPlugin(resId)
+	c, err := l.loadGoPlugin(resId, absPluginPath+".so")
 	if err != nil {
 		return nil, err
 	}
@@ -208,12 +250,11 @@ func (l *Loader) loadExecOrGoPlugin(resId resid.ResId) (resmap.Configurable, err
 // as a Loader instance variable.  So make it a package variable.
 var registry = make(map[string]resmap.Configurable)
 
-func (l *Loader) loadGoPlugin(id resid.ResId) (resmap.Configurable, error) {
+func (l *Loader) loadGoPlugin(id resid.ResId, absPath string) (resmap.Configurable, error) {
 	regId := relativePluginPath(id)
 	if c, ok := registry[regId]; ok {
 		return copyPlugin(c), nil
 	}
-	absPath := l.absolutePluginPath(id) + ".so"
 	if !utils.FileExists(absPath) {
 		return nil, fmt.Errorf(
 			"expected file with Go object code at: %s", absPath)

api/internal/plugins/loader/loader_test.go

@@ -66,10 +66,7 @@ func TestLoader(t *testing.T) {
 	for _, behavior := range []types.BuiltinPluginLoadingOptions{
 		/* types.BploUseStaticallyLinked,
 		types.BploLoadFromFileSys */} {
-		c, err := konfig.EnabledPluginConfig(behavior)
-		if err != nil {
-			t.Fatal(err)
-		}
+		c := konfig.EnabledPluginConfig(behavior)
 		pLdr := NewLoader(c, rmF)
 		if pLdr == nil {
 			t.Fatal("expect non-nil loader")

api/internal/plugins/utils/utils.go

@@ -34,7 +34,7 @@ func GoBin() string {
 // has her ${g}/${v}/$lower(${k})/${k}.go files.
 func DeterminePluginSrcRoot(fSys filesys.FileSystem) (string, error) {
 	return konfig.FirstDirThatExistsElseError(
-		"source directory", fSys, []konfig.NotedFunc{
+		"plugin src root", fSys, []konfig.NotedFunc{
 			{
 				Note: "relative to unit test",
 				F: func() string {

api/konfig/plugins.go

@@ -41,28 +41,20 @@ const (
 	NoPluginHomeSentinal = "/No/non-builtin/plugins!"
 )
 
-func EnabledPluginConfig(b types.BuiltinPluginLoadingOptions) (*types.PluginConfig, error) {
-	dir, err := DefaultAbsPluginHome(filesys.MakeFsOnDisk())
-	if err != nil {
-		return nil, err
-	}
-	return MakePluginConfig(types.PluginRestrictionsNone, b, dir), nil
+func EnabledPluginConfig(b types.BuiltinPluginLoadingOptions) *types.PluginConfig {
+	return MakePluginConfig(types.PluginRestrictionsNone, b)
 }
 
 func DisabledPluginConfig() *types.PluginConfig {
 	return MakePluginConfig(
 		types.PluginRestrictionsBuiltinsOnly,
-		types.BploUseStaticallyLinked,
-		NoPluginHomeSentinal)
+		types.BploUseStaticallyLinked)
 }
 
-func MakePluginConfig(
-	pr types.PluginRestrictions,
-	b types.BuiltinPluginLoadingOptions,
-	home string) *types.PluginConfig {
+func MakePluginConfig(pr types.PluginRestrictions,
+	b types.BuiltinPluginLoadingOptions) *types.PluginConfig {
 	return &types.PluginConfig{
 		PluginRestrictions: pr,
-		AbsPluginHome:      home,
 		BpLoadingOptions:   b,
 	}
 }
@@ -77,7 +69,7 @@ type NotedFunc struct {
 // the home of kustomize plugins.
 func DefaultAbsPluginHome(fSys filesys.FileSystem) (string, error) {
 	return FirstDirThatExistsElseError(
-		"plugin home directory", fSys, []NotedFunc{
+		"plugin root", fSys, []NotedFunc{
 			{
 				Note: "homed in $" + KustomizePluginHomeEnv,
 				F: func() string {

api/krusty/fnplugin_test.go

@@ -8,8 +8,8 @@ import (
 )
 
 func TestFnExecGenerator(t *testing.T) {
-	th := kusttest_test.MakeEnhancedHarness(t)
-	defer th.Reset()
+	// Function plugins should not need the env setup done by MakeEnhancedHarness
+	th := kusttest_test.MakeHarness(t)
 
 	th.WriteK(".", `
 resources:
@@ -92,8 +92,8 @@ func skipIfNoDocker(t *testing.T) {
 func TestFnContainerGenerator(t *testing.T) {
 	skipIfNoDocker(t)
 
-	th := kusttest_test.MakeEnhancedHarness(t)
-	defer th.Reset()
+	// Function plugins should not need the env setup done by MakeEnhancedHarness
+	th := kusttest_test.MakeHarness(t)
 
 	th.WriteK(".", `
 resources:
@@ -308,8 +308,8 @@ spec:
 func TestFnContainerTransformer(t *testing.T) {
 	skipIfNoDocker(t)
 
-	th := kusttest_test.MakeEnhancedHarness(t)
-	defer th.Reset()
+	// Function plugins should not need the env setup done by MakeEnhancedHarness
+	th := kusttest_test.MakeHarness(t)
 
 	th.WriteK(".", `
 resources:
@@ -408,8 +408,8 @@ spec:
 func TestFnContainerTransformerWithConfig(t *testing.T) {
 	skipIfNoDocker(t)
 
-	th := kusttest_test.MakeEnhancedHarness(t)
-	defer th.Reset()
+	// Function plugins should not need the env setup done by MakeEnhancedHarness
+	th := kusttest_test.MakeHarness(t)
 
 	th.WriteK(".", `
 resources:
@@ -468,8 +468,8 @@ metadata:
 func TestFnContainerEnvVars(t *testing.T) {
 	skipIfNoDocker(t)
 
-	th := kusttest_test.MakeEnhancedHarness(t)
-	defer th.Reset()
+	// Function plugins should not need the env setup done by MakeEnhancedHarness
+	th := kusttest_test.MakeHarness(t)
 
 	th.WriteK(".", `
 generators:

api/testutils/kusttest/harness.go

@@ -5,7 +5,6 @@ package kusttest_test
 
 import (
 	"path/filepath"
-	"strings"
 	"testing"
 
 	"sigs.k8s.io/kustomize/api/filesys"
@@ -77,15 +76,7 @@ func (th Harness) MakeOptionsPluginsDisabled() krusty.Options {
 
 // Enables use of non-builtin plugins.
 func (th Harness) MakeOptionsPluginsEnabled() krusty.Options {
-	pc, err := konfig.EnabledPluginConfig(types.BploLoadFromFileSys)
-	if err != nil {
-		if strings.Contains(err.Error(), "unable to find plugin root") {
-			th.t.Log(
-				"Tests that want to run with plugins enabled must be " +
-					"bookended by calls to MakeEnhancedHarness(), Reset().")
-		}
-		th.t.Fatal(err)
-	}
+	pc := konfig.EnabledPluginConfig(types.BploLoadFromFileSys)
 	o := *krusty.MakeDefaultOptions()
 	o.PluginConfig = pc
 	return o

api/testutils/kusttest/harnessenhanced.go

@@ -40,11 +40,8 @@ type HarnessEnhanced struct {
 func MakeEnhancedHarness(t *testing.T) *HarnessEnhanced {
 	pte := newPluginTestEnv(t).set()
 
-	pc, err := konfig.EnabledPluginConfig(types.BploLoadFromFileSys)
+	pc := konfig.EnabledPluginConfig(types.BploLoadFromFileSys)
 	pc.FnpLoadingOptions.EnableStar = true
-	if err != nil {
-		t.Fatal(err)
-	}
 	p := provider.NewDefaultDepProvider()
 	resourceFactory := p.GetResourceFactory()
 	resmapFactory := resmap.NewFactory(resourceFactory)

api/types/errunabletofind.go

@@ -23,7 +23,7 @@ func (e *errUnableToFind) Error() string {
 		m = append(m, "('"+p.Value+"'; "+p.Key+")")
 	}
 	return fmt.Sprintf(
-		"unable to find plugin root - tried: %s", strings.Join(m, ", "))
+		"unable to find %s - tried: %s", e.what, strings.Join(m, ", "))
 }
 
 func NewErrUnableToFind(w string, a []Pair) *errUnableToFind {

api/types/pluginconfig.go

@@ -5,25 +5,6 @@ package types
 
 // PluginConfig holds plugin configuration.
 type PluginConfig struct {
-	// AbsPluginHome is the home of kustomize plugins.
-	// Kustomize plugin configuration files are k8s-style objects
-	// containing the fields 'apiVersion' and 'kind', e.g.
-	//   apiVersion: apps/v1
-	//   kind: Deployment
-	// kustomize reads plugin configuration data from a file path
-	// specified in the 'generators:' or 'transformers:' field of a
-	// kustomization file.  kustomize must then use this data to both
-	// locate the plugin and configure it.
-	// Every kustomize plugin (its code, its tests, its supporting data
-	// files, etc.) must be housed in its own directory at
-	//   ${AbsPluginHome}/${pluginApiVersion}/LOWERCASE(${pluginKind})
-	// where
-	//   - ${AbsPluginHome} is an absolute path, defined below.
-	//   - ${pluginApiVersion} is taken from the plugin config file.
-	//   - ${pluginKind} is taken from the plugin config file.
-	// The value of AbsPluginHome can be any absolute path.
-	AbsPluginHome string
-
 	// PluginRestrictions distinguishes plugin restrictions.
 	PluginRestrictions PluginRestrictions
 

kustomize/commands/build/build.go

@@ -6,7 +6,6 @@ package build
 import (
 	"fmt"
 	"io"
-	"log"
 
 	"github.com/spf13/cobra"
 	"sigs.k8s.io/kustomize/api/filesys"
@@ -130,10 +129,7 @@ func HonorKustomizeFlags(kOpts *krusty.Options) *krusty.Options {
 	kOpts.DoLegacyResourceSort = getFlagReorderOutput() == legacy
 	kOpts.LoadRestrictions = getFlagLoadRestrictorValue()
 	if theFlags.enable.plugins {
-		c, err := konfig.EnabledPluginConfig(types.BploUseStaticallyLinked)
-		if err != nil {
-			log.Fatal(err)
-		}
+		c := konfig.EnabledPluginConfig(types.BploUseStaticallyLinked)
 		c.FnpLoadingOptions = theFlags.fnOptions
 		kOpts.PluginConfig = c
 	}