add error types for kptfile validation and image

e2e/testdata/fn-eval/missing-fn-image/.expected/config.yaml

@@ -17,7 +17,7 @@ exitCode: 1
 image: gcr.io/kpt-fn/dne # non-existing image
 args:
   namespace: staging
-stdErr: "error: function image \"gcr.io/kpt-fn/dne\" doesn't exist"
+stdErr: 'Function image "gcr.io/kpt-fn/dne" doesn''t exist'
 stdOut: |
   [RUNNING] "gcr.io/kpt-fn/dne"
   [FAIL] "gcr.io/kpt-fn/dne"

e2e/testdata/fn-render/invalid-inline-fnconfig/.expected/config.yaml

@@ -13,4 +13,4 @@
 # limitations under the License.
 
 exitCode: 1
-stdErr: 'Error: invalid pipeline: function "gcr.io/kpt-fn/set-labels:unstable": functionConfig must be a valid KRM resource with `apiVersion` and `kind` fields'
+stdErr: "functionConfig must be a valid KRM resource with `apiVersion` and `kind` fields"

e2e/testdata/fn-render/missing-fn-image/.expected/config.yaml

@@ -13,7 +13,7 @@
 # limitations under the License.
 
 exitCode: 1
-stdErr: "Error: function image \"gcr.io/kpt-fn/set-labels1\" doesn't exist"
+stdErr: 'Error: Function image "gcr.io/kpt-fn/dne" doesn''t exist'
 stdOut: |
   [RUNNING] "gcr.io/kpt-fn/set-namespace:unstable"
   [PASS] "gcr.io/kpt-fn/set-namespace:unstable"

e2e/testdata/fn-render/missing-fn-image/Kptfile

@@ -7,6 +7,6 @@ pipeline:
   - image: gcr.io/kpt-fn/set-namespace:unstable
     configMap:
       namespace: staging
-  - image: gcr.io/kpt-fn/set-labels1 # non-existing image
+  - image: gcr.io/kpt-fn/dne # non-existing image
     configMap:
-      tier: backend
+      tier: backend

e2e/testdata/fn-render/multiple-fnconfig/.expected/config.yaml

@@ -13,4 +13,4 @@
 # limitations under the License.
 
 exitCode: 1
-stdErr: "following fields are mutually exclusive: 'config', 'configMap', 'configPath'. Got \"configPath, configMap\""
+stdErr: 'only one of ''config'', ''configMap'', ''configPath'' can be specified. Got "configPath, configMap"'

internal/errors/resolver/container.go

@@ -0,0 +1,41 @@
+// Copyright 2021 Google LLC
+//
+// 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 resolver
+
+import (
+	"errors"
+
+	"github.com/GoogleContainerTools/kpt/internal/fnruntime"
+)
+
+//nolint:gochecknoinits
+func init() {
+	AddErrorResolver(&containerImageErrorResolver{})
+}
+
+// containerImageErrorResolver is an implementation of the ErrorResolver interface
+// to resolve container image errors.
+type containerImageErrorResolver struct{}
+
+func (*containerImageErrorResolver) Resolve(err error) (ResolvedResult, bool) {
+	var containerImageError *fnruntime.ContainerImageError
+	if !errors.As(err, &containerImageError) {
+		return ResolvedResult{}, false
+	}
+	return ResolvedResult{
+		Message:  containerImageError.Error(),
+		ExitCode: 1,
+	}, true
+}

internal/errors/resolver/pkg.go

@@ -19,6 +19,7 @@ import (
 
 	"github.com/GoogleContainerTools/kpt/internal/errors"
 	"github.com/GoogleContainerTools/kpt/internal/pkg"
+	kptfile "github.com/GoogleContainerTools/kpt/pkg/api/kptfile/v1alpha2"
 )
 
 //nolint:gochecknoinits
@@ -44,6 +45,7 @@ type pkgErrorResolver struct{}
 
 func (*pkgErrorResolver) Resolve(err error) (ResolvedResult, bool) {
 	var kptfileError *pkg.KptfileError
+	var validateError *kptfile.ValidateError
 	if errors.As(err, &kptfileError) {
 		path := kptfileError.Path
 		tmplArgs := map[string]interface{}{
@@ -63,6 +65,12 @@ func (*pkgErrorResolver) Resolve(err error) (ResolvedResult, bool) {
 			ExitCode: 1,
 		}, true
 	}
+	if errors.As(err, &validateError) {
+		return ResolvedResult{
+			Message:  validateError.Error(),
+			ExitCode: 1,
+		}, true
+	}
 
 	return ResolvedResult{}, false
 }

internal/fnruntime/container.go

@@ -163,7 +163,10 @@ func (f *ContainerFn) prepareImage() error {
 	var output []byte
 	var err error
 	if output, err = cmd.CombinedOutput(); err != nil {
-		return fmt.Errorf("failed to check local function image %q: %w", f.Image, err)
+		return &ContainerImageError{
+			Image:  f.Image,
+			Output: string(output),
+		}
 	}
 	if strings.Contains(string(output), strings.Split(f.Image, ":")[0]) {
 		// image exists locally
@@ -178,8 +181,22 @@ func (f *ContainerFn) prepareImage() error {
 	ctx, cancel := context.WithTimeout(context.Background(), timeout)
 	defer cancel()
 	cmd = exec.CommandContext(ctx, dockerBin, args...)
-	if _, err := cmd.CombinedOutput(); err != nil {
-		return fmt.Errorf("function image %q doesn't exist", f.Image)
+	if output, err := cmd.CombinedOutput(); err != nil {
+		return &ContainerImageError{
+			Image:  f.Image,
+			Output: string(output),
+		}
 	}
 	return nil
 }
+
+// ContainerImageError is an error type which will be returned when
+// the container run time cannot verify docker image.
+type ContainerImageError struct {
+	Image  string
+	Output string
+}
+
+func (e *ContainerImageError) Error() string {
+	return fmt.Sprintf("Function image %q doesn't exist.", e.Image)
+}

internal/util/addmergecomment/addmergecomment.go

@@ -1,3 +1,17 @@
+// Copyright 2021 Google LLC
+//
+// 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 addmergecomment
 
 import (

internal/util/addmergecomment/addmergecomment_test.go

@@ -1,3 +1,17 @@
+// Copyright 2021 Google LLC
+//
+// 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 addmergecomment
 
 import (

pkg/api/kptfile/v1alpha2/validation.go

@@ -41,29 +41,41 @@ func (p *Pipeline) validate() error {
 	if p == nil {
 		return nil
 	}
-	fns := []Function{}
-	fns = append(fns, p.Mutators...)
-	fns = append(fns, p.Validators...)
-	for i := range fns {
-		f := fns[i]
-		err := f.validate()
+	for i := range p.Mutators {
+		f := p.Mutators[i]
+		err := f.validate("mutators", i)
+		if err != nil {
+			return fmt.Errorf("function %q: %w", f.Image, err)
+		}
+	}
+	for i := range p.Validators {
+		f := p.Validators[i]
+		err := f.validate("validators", i)
 		if err != nil {
 			return fmt.Errorf("function %q: %w", f.Image, err)
 		}
 	}
 	return nil
 }
 
-func (f *Function) validate() error {
+func (f *Function) validate(fnType string, idx int) error {
 	err := validateFunctionName(f.Image)
 	if err != nil {
-		return fmt.Errorf("'image' is invalid: %w", err)
+		return &ValidateError{
+			Field:  fmt.Sprintf("pipeline.%s[%d].image", fnType, idx),
+			Value:  f.Image,
+			Reason: err.Error(),
+		}
 	}
 
 	var configFields []string
 	if f.ConfigPath != "" {
 		if err := validatePath(f.ConfigPath); err != nil {
-			return fmt.Errorf("'configPath' %q is invalid: %w", f.ConfigPath, err)
+			return &ValidateError{
+				Field:  fmt.Sprintf("pipeline.%s[%d].configPath", fnType, idx),
+				Value:  f.ConfigPath,
+				Reason: err.Error(),
+			}
 		}
 		configFields = append(configFields, "configPath")
 	}
@@ -73,13 +85,19 @@ func (f *Function) validate() error {
 	if !IsNodeZero(&f.Config) {
 		config := yaml.NewRNode(&f.Config)
 		if _, err := config.GetMeta(); err != nil {
-			return fmt.Errorf("functionConfig must be a valid KRM resource with `apiVersion` and `kind` fields")
+			return &ValidateError{
+				Field:  fmt.Sprintf("pipeline.%s[%d].config", fnType, idx),
+				Reason: "functionConfig must be a valid KRM resource with `apiVersion` and `kind` fields",
+			}
 		}
 		configFields = append(configFields, "config")
 	}
 	if len(configFields) > 1 {
-		return fmt.Errorf("following fields are mutually exclusive: 'config', 'configMap', 'configPath'. Got %q",
-			strings.Join(configFields, ", "))
+		return &ValidateError{
+			Field: fmt.Sprintf("pipeline.%s[%d]", fnType, idx),
+			Reason: fmt.Sprintf("only one of 'config', 'configMap', 'configPath' can be specified. Got %q",
+				strings.Join(configFields, ", ")),
+		}
 	}
 
 	return nil
@@ -148,3 +166,23 @@ func validatePath(p string) error {
 	}
 	return nil
 }
+
+// ValidateError is the error returned when validation fails.
+type ValidateError struct {
+	// Field is the field that causes error
+	Field string
+	// Value is the value of invalid field
+	Value string
+	// Reason is the reson for the error
+	Reason string
+}
+
+func (e *ValidateError) Error() string {
+	var sb strings.Builder
+	sb.WriteString(fmt.Sprintf("Kptfile is invalid:\nField: `%s`\n", e.Field))
+	if e.Value != "" {
+		sb.WriteString(fmt.Sprintf("Value: %q\n", e.Value))
+	}
+	sb.WriteString(fmt.Sprintf("Reason: %s\n", e.Reason))
+	return sb.String()
+}