improve kpt fn render error messages (kptdev#1955)

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: 'failed to check function image existence: function image "gcr.io/kpt-fn/dne" doesn''t exist'
+stdErr: "error: 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

@@ -13,7 +13,4 @@
 # limitations under the License.
 
 exitCode: 1
-stdErr: "missing Resource metadata"
-stdOut: |
-  [RUNNING] "gcr.io/kpt-fn/set-namespace:unstable"
-  [PASS] "gcr.io/kpt-fn/set-namespace:unstable"
+stdErr: 'Error: invalid pipeline: function "gcr.io/kpt-fn/set-label:unstable": 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: 'failed to check function image existence: function image "gcr.io/kpt-fn/set-label1" doesn''t exist:'
+stdErr: "Error: function image \"gcr.io/kpt-fn/set-label1\" doesn't exist"
 stdOut: |
   [RUNNING] "gcr.io/kpt-fn/set-namespace:unstable"
   [PASS] "gcr.io/kpt-fn/set-namespace:unstable"

e2e/testdata/fn-render/no-pipeline-in-subpackage/.expected/diff.patch

@@ -0,0 +1,35 @@
+diff --git a/db/resources.yaml b/db/resources.yaml
+index 10cd18b..a9dd224 100644
+--- a/db/resources.yaml
++++ b/db/resources.yaml
+@@ -11,17 +11,29 @@
+ # 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.
+-
+ apiVersion: apps/v1
+ kind: Deployment
+ metadata:
+   name: nginx-deployment
++  namespace: staging
++  labels:
++    tier: backend
+ spec:
+   replicas: 3
++  selector:
++    matchLabels:
++      tier: backend
++  template:
++    metadata:
++      labels:
++        tier: backend
+ ---
+ apiVersion: custom.io/v1
+ kind: Custom
+ metadata:
+   name: custom
++  namespace: staging
++  labels:
++    tier: backend
+ spec:
+   image: nginx:1.2.3

e2e/testdata/fn-render/no-pipeline-in-subpackage/.krmignore

@@ -0,0 +1 @@
+.expected

e2e/testdata/fn-render/no-pipeline-in-subpackage/Kptfile

@@ -0,0 +1,12 @@
+apiVersion: kpt.dev/v1alpha2
+kind: Kptfile
+metadata:
+  name: app
+pipeline:
+  mutators:
+  - image: gcr.io/kpt-fn/set-namespace:unstable
+    configMap:
+      namespace: staging
+  - image: gcr.io/kpt-fn/set-label:unstable
+    configMap:
+      tier: backend

e2e/testdata/fn-render/no-pipeline-in-subpackage/db/Kptfile

@@ -0,0 +1,4 @@
+apiVersion: kpt.dev/v1alpha2
+kind: Kptfile
+metadata:
+  name: app

e2e/testdata/fn-render/resource-has-pkgname-prefix/.expected/config.yaml → e2e/testdata/fn-render/no-pipeline-in-subpackage/db/resources.yaml

@@ -12,4 +12,16 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-exitCode: 0
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: nginx-deployment
+spec:
+  replicas: 3
+---
+apiVersion: custom.io/v1
+kind: Custom
+metadata:
+  name: custom
+spec:
+  image: nginx:1.2.3

internal/fnruntime/container.go

@@ -77,7 +77,7 @@ func (f *ContainerFn) Run(reader io.Reader, writer io.Writer) error {
 	// output
 	err := f.prepareImage()
 	if err != nil {
-		return fmt.Errorf("failed to check function image existence: %w", err)
+		return err
 	}
 
 	errSink := bytes.Buffer{}
@@ -164,7 +164,7 @@ func (f *ContainerFn) prepareImage() error {
 	defer cancel()
 	cmd = exec.CommandContext(ctx, dockerBin, args...)
 	if _, err := cmd.CombinedOutput(); err != nil {
-		return fmt.Errorf("function image %q doesn't exist: %w", f.Image, err)
+		return fmt.Errorf("function image %q doesn't exist", f.Image)
 	}
 	return nil
 }

pkg/api/kptfile/v1alpha2/validation.go

@@ -19,7 +19,6 @@ import (
 	"regexp"
 	"strings"
 
-	"github.com/GoogleContainerTools/kpt/internal/errors"
 	"sigs.k8s.io/kustomize/kyaml/yaml"
 )
 
@@ -28,9 +27,8 @@ const (
 )
 
 func (kf *KptFile) Validate() error {
-	const op errors.Op = "v1alpha2.kptfile.validate"
 	if err := kf.Pipeline.validate(); err != nil {
-		return errors.E(op, fmt.Errorf("pipeline is not valid: %w", err))
+		return fmt.Errorf("invalid pipeline: %w", err)
 	}
 	// TODO: validate other fields
 	return nil
@@ -40,7 +38,6 @@ func (kf *KptFile) Validate() error {
 // 'mutators' and 'validators' share same schema and
 // they are valid if all functions in them are ALL valid.
 func (p *Pipeline) validate() error {
-	const op errors.Op = "v1alpha2.pipeline.validate"
 	if p == nil {
 		return nil
 	}
@@ -51,7 +48,7 @@ func (p *Pipeline) validate() error {
 		f := fns[i]
 		err := f.validate()
 		if err != nil {
-			return errors.E(op, fmt.Errorf("function %q is invalid: %w", f.Image, err))
+			return fmt.Errorf("function %q: %w", f.Image, err)
 		}
 	}
 	return nil
@@ -74,6 +71,10 @@ func (f *Function) validate() error {
 		configFields = append(configFields, "configMap")
 	}
 	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")
+		}
 		configFields = append(configFields, "config")
 	}
 	if len(configFields) > 1 {