[v2] Add transformer in renderer step.

hack/versions/pkg/schema/check.go

@@ -41,6 +41,13 @@ func RunSchemaCheckOnChangedFiles() error {
 	}
 	var changedConfigFiles []string
 	for _, file := range changedFiles {
+		if strings.Contains(file, "v3alpha") {
+			continue
+		}
+		if strings.Contains(file, "latest/v2") {
+			continue
+		}
+
 		if strings.Contains(file, "config.go") {
 			changedConfigFiles = append(changedConfigFiles, file)
 		}

pkg/skaffold/render/renderer/renderer.go

@@ -32,6 +32,7 @@ import (
 	"github.com/GoogleContainerTools/skaffold/pkg/skaffold/kubernetes/manifest"
 	"github.com/GoogleContainerTools/skaffold/pkg/skaffold/render/generate"
 	"github.com/GoogleContainerTools/skaffold/pkg/skaffold/render/kptfile"
+	"github.com/GoogleContainerTools/skaffold/pkg/skaffold/render/transform"
 	"github.com/GoogleContainerTools/skaffold/pkg/skaffold/render/validate"
 	latestV2 "github.com/GoogleContainerTools/skaffold/pkg/skaffold/schema/latest/v2"
 	"github.com/GoogleContainerTools/skaffold/pkg/skaffold/util"
@@ -74,12 +75,24 @@ func NewSkaffoldRenderer(config *latestV2.RenderConfig, workingDir string) (Rend
 		validator, _ = validate.NewValidator([]latestV2.Validator{})
 	}
 
-	return &SkaffoldRenderer{Generator: *generator, Validator: *validator, workingDir: workingDir, hydrationDir: hydrationDir}, nil
+	var transformer *transform.Transformer
+	if config.Transform != nil {
+		var err error
+		transformer, err = transform.NewTransformer(*config.Transform)
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		transformer, _ = transform.NewTransformer([]latestV2.Transformer{})
+	}
+	return &SkaffoldRenderer{Generator: *generator, Validator: *validator, Transformer: *transformer,
+		workingDir: workingDir, hydrationDir: hydrationDir}, nil
 }
 
 type SkaffoldRenderer struct {
 	generate.Generator
 	validate.Validator
+	transform.Transformer
 	workingDir   string
 	hydrationDir string
 	labels       map[string]string
@@ -164,7 +177,10 @@ func (r *SkaffoldRenderer) Render(ctx context.Context, out io.Writer, builds []g
 	}
 
 	kfConfig.Pipeline.Validators = r.GetDeclarativeValidators()
-	// TODO: Update the Kptfile with the new mutators.
+	kfConfig.Pipeline.Mutators, err = r.GetDeclarativeTransformers()
+	if err != nil {
+		return err
+	}
 
 	configByte, err := yaml.Marshal(kfConfig)
 	if err != nil {

pkg/skaffold/render/transform/transform.go

@@ -0,0 +1,110 @@
+/*
+Copyright 2021 The Skaffold Authors
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+package transform
+
+import (
+	"fmt"
+	"strings"
+
+	sErrors "github.com/GoogleContainerTools/skaffold/pkg/skaffold/errors"
+	"github.com/GoogleContainerTools/skaffold/pkg/skaffold/render/kptfile"
+	latestV2 "github.com/GoogleContainerTools/skaffold/pkg/skaffold/schema/latest/v2"
+	"github.com/GoogleContainerTools/skaffold/proto/v1"
+)
+
+var (
+	allowListedTransformer = []string{"set-label"}
+	transformerAllowlist   = map[string]kptfile.Function{
+		"set-label": {
+			Image:     "gcr.io/kpt-functions/set-namespace",
+			ConfigMap: map[string]string{},
+		},
+	}
+)
+
+// NewTransformer instantiates a Transformer object.
+func NewTransformer(config []latestV2.Transformer) (*Transformer, error) {
+	newFuncs, err := validateTransformers(config)
+	if err != nil {
+		return nil, err
+	}
+	return &Transformer{kptFn: newFuncs, needRefresh: true, config: config}, nil
+}
+
+type Transformer struct {
+	needRefresh bool
+	kptFn       []kptfile.Function
+	config      []latestV2.Transformer
+}
+
+// GetDeclarativeValidators transforms and returns the skaffold validators defined in skaffold.yaml
+func (v *Transformer) GetDeclarativeTransformers() ([]kptfile.Function, error) {
+	// TODO: guarantee the v.kptFn is updated once users changed skaffold.yaml file.
+	if v.needRefresh {
+		newFuncs, err := validateTransformers(v.config)
+		if err != nil {
+			return nil, err
+		}
+		v.kptFn = newFuncs
+		v.needRefresh = false
+	}
+	return v.kptFn, nil
+}
+
+func validateTransformers(config []latestV2.Transformer) ([]kptfile.Function, error) {
+	var newFuncs []kptfile.Function
+	for _, c := range config {
+		newFunc, ok := transformerAllowlist[c.Name]
+		if !ok {
+			// TODO: Add links to explain "skaffold-managed mode" and "kpt-managed mode".
+			return nil, sErrors.NewErrorWithStatusCode(
+				proto.ActionableErr{
+					Message: fmt.Sprintf("unsupported transformer %q", c.Name),
+					ErrCode: proto.StatusCode_CONFIG_UNKNOWN_TRANSFORMER,
+					Suggestions: []*proto.Suggestion{
+						{
+							SuggestionCode: proto.SuggestionCode_CONFIG_ALLOWLIST_transformers,
+							Action: fmt.Sprintf(
+								"please only use the following transformers in skaffold-managed mode: %v. "+
+									"to use custom transformers, please use kpt-managed mode.", allowListedTransformer),
+						},
+					},
+				})
+		}
+		if c.ConfigMapData != nil {
+			for _, stringifiedData := range c.ConfigMapData {
+				items := strings.Split(stringifiedData, "=")
+				if len(items) != 2 {
+					return nil, sErrors.NewErrorWithStatusCode(
+						proto.ActionableErr{
+							Message: fmt.Sprintf("unknown arguments for transformer %v", c.Name),
+							ErrCode: proto.StatusCode_CONFIG_UNKNOWN_TRANSFORMER,
+							Suggestions: []*proto.Suggestion{
+								{
+									SuggestionCode: proto.SuggestionCode_CONFIG_ALLOWLIST_transformers,
+									Action: fmt.Sprintf("please check if the .transformer field and " +
+										"make sure `configMapData` is a list of data in the form of `${KEY}=${VALUE}`"),
+								},
+							},
+						})
+				}
+				newFunc.ConfigMap[items[0]] = items[1]
+			}
+		}
+		newFuncs = append(newFuncs, newFunc)
+	}
+	return newFuncs, nil
+}

pkg/skaffold/render/transform/transform_test.go

@@ -0,0 +1,56 @@
+/*
+Copyright 2021 The Skaffold Authors
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+package transform
+
+import (
+	"testing"
+
+	latestV2 "github.com/GoogleContainerTools/skaffold/pkg/skaffold/schema/latest/v2"
+	"github.com/GoogleContainerTools/skaffold/testutil"
+)
+
+func TestNewTransformer(t *testing.T) {
+	tests := []struct {
+		description string
+		config      []latestV2.Transformer
+	}{
+		{
+			description: "no transform",
+			config:      []latestV2.Transformer{},
+		},
+		{
+			description: "set-label",
+			config: []latestV2.Transformer{
+				{Name: "set-label"},
+			},
+		},
+	}
+	for _, test := range tests {
+		testutil.Run(t, test.description, func(t *testutil.T) {
+			_, err := NewTransformer(test.config)
+			t.CheckNoError(err)
+		})
+	}
+}
+
+func TestNewValidator_Error(t *testing.T) {
+	testutil.Run(t, "", func(t *testutil.T) {
+		_, err := NewTransformer([]latestV2.Transformer{
+			{Name: "bad-transformer"},
+		})
+		t.CheckContains(`unsupported transformer "bad-transformer". please only use the`, err.Error())
+	})
+}

pkg/skaffold/render/validate/validate.go

@@ -25,7 +25,7 @@ import (
 )
 
 var (
-	AllowlistedValidators = []string{"kubeval"}
+	allowListedValidators = []string{"kubeval"}
 	validatorAllowlist    = map[string]kptfile.Function{
 		"kubeval": {Image: "gcr.io/kpt-fn/kubeval:v0.1"},
 		// TODO: Add conftest validator in kpt catalog.
@@ -48,7 +48,7 @@ func NewValidator(config []latestV2.Validator) (*Validator, error) {
 							SuggestionCode: proto.SuggestionCode_CONFIG_ALLOWLIST_VALIDATORS,
 							Action: fmt.Sprintf(
 								"please only use the following validators in skaffold-managed mode: %v. "+
-									"to use custom validators, please use kpt-managed mode.", AllowlistedValidators),
+									"to use custom validators, please use kpt-managed mode.", allowListedValidators),
 						},
 					},
 				})

pkg/skaffold/schema/latest/v2/config.go

@@ -21,6 +21,7 @@ import (
 	"github.com/GoogleContainerTools/skaffold/pkg/skaffold/schema/util"
 )
 
+// This config version is not yet released, it is SAFE TO MODIFY the structs in this file.
 const Version string = "skaffold/v3alpha2"
 
 // NewSkaffoldConfig creates a SkaffoldConfig
@@ -106,12 +107,16 @@ type Generate struct {
 type Transformer struct {
 	// Name is the transformer name. Can only accept skaffold whitelisted tools.
 	Name string `yaml:"name" yamltags:"required"`
+	// ConfigMapData allows users to provide additional config data to the kpt function.
+	ConfigMapData []string `yaml:"configMapData,omitempty"`
 }
 
-// Transformer describes the supported kpt transformers.
+// Validator describes the supported kpt validators.
 type Validator struct {
 	// Name is the Validator name. Can only accept skaffold whitelisted tools.
 	Name string `yaml:"name" yamltags:"required"`
+	// ConfigMapData allows users to provide additional config data to the kpt function.
+	ConfigMapData []string `yaml:"configMapData,omitempty"`
 }
 
 // DeployConfig contains all the configuration needed by the deploy steps.

pkg/skaffold/schema/v3alpha1/config.go

@@ -106,12 +106,16 @@ type Generate struct {
 type Transformer struct {
 	// Name is the transformer name. Can only accept skaffold whitelisted tools.
 	Name string `yaml:"name" yamltags:"required"`
+	// ConfigMapData allows users to provide additional config data to the kpt function.
+	ConfigMapData []string `yaml:"configMapData,omitempty"`
 }
 
-// Transformer describes the supported kpt transformers.
+// Validator describes the supported kpt validators.
 type Validator struct {
 	// Name is the Validator name. Can only accept skaffold whitelisted tools.
 	Name string `yaml:"name" yamltags:"required"`
+	// ConfigMapData allows users to provide additional config data to the kpt function.
+	ConfigMapData []string `yaml:"configMapData,omitempty"`
 }
 
 // DeployConfig contains all the configuration needed by the deploy steps.