UX improvements to kyaml/fn/framework

kyaml/fn/framework/doc.go

@@ -6,7 +6,20 @@
 //
 // Examples
 //
-// Example function implementation using framework.ResourceList with functionConfig
+// Example function implementation using framework.Command with flag input
+//
+//      var value string
+//      resourceList := &framework.ResourceList{}
+//      cmd := framework.Command(resourceList, func() error {
+//        for i := range resourceList.Items {
+//          // modify the items...
+//        }
+//        return nil
+//      })
+//      cmd.Flags().StringVar(&value, "value", "", "annotation value")
+//      if err := cmd.Execute(); err != nil { return err }
+//
+// Example function implementation using framework.ResourceList with a struct input
 //
 //    type Spec struct {
 //      Value string `yaml:"value,omitempty"`
@@ -24,23 +37,11 @@
 //    }
 //    if err := rl.Write(); err != nil { return err }
 //
-// Example function implementation using framework.Command with flags
-//
-//      var value string
-//      cmd := framework.Command(nil, func(items []*yaml.RNode) ([]*yaml.RNode, error) {
-//        for i := range items {
-//          // modify the items...
-//        }
-//        return items, nil
-//      })
-//      cmd.Flags().StringVar(&value, "value", "", "annotation value")
-//      if err := cmd.Execute(); err != nil { return err }
-//
 // Architecture
 //
-// Functions modify a slice of resources (ResourceList.items) which are read as input and written
+// Functions modify a slice of resources (ResourceList.Items) which are read as input and written
 // as output.  The function itself may be configured through a functionConfig
-// (ResourceList.functionConfig).
+// (ResourceList.FunctionConfig).
 //
 // Example Function Input:
 //
@@ -67,7 +68,7 @@
 //        # run the function by creating this container and providing this
 //        # Example as the functionConfig
 //        config.kubernetes.io/function: |
-//          image: image/containing/fuction:impl
+//          image: image/containing/function:impl
 //    spec:
 //      value: foo
 //
@@ -77,7 +78,7 @@
 //
 // Functions may also be specified imperatively and run using:
 //
-//   config run DIR/ --image image/containing/fuction:impl -- value=foo
+//   config run DIR/ --image image/containing/function:impl -- value=foo
 //
 // When run imperatively, a ConfigMap is generated for the functionConfig, and the command
 // arguments are set as ConfigMap data entries.
@@ -91,15 +92,11 @@
 //
 // Mutator and Generator Functions
 //
-// Functions may add, delete or modify resources by modifying the items slice.
-// When using framework.Command this is done through returning the new items slice.
-// When using framework.ResourceList this is done through modifying ResourceList.Items in place.
+// Functions may add, delete or modify resources by modifying the ResourceList.Items slice.
 //
 // Validator Functions
 //
-// A function may validate resources by providing a Result.
-// When using framework.Command this is done through returning a framework.Result as an error.
-// WHen using framework.ResourceList this is done through setting ResourceList.Result.
+// A function may emit validation results by setting the ResourceList.Result
 //
 // Configuring Functions
 //

kyaml/fn/framework/example/main.go

@@ -12,14 +12,16 @@ import (
 
 func main() {
 	var value string
-	cmd := framework.Command(nil, func(items []*yaml.RNode) ([]*yaml.RNode, error) {
-		for i := range items {
+	resourceList := framework.ResourceList{}
+	cmd := framework.Command(&resourceList, func() error {
+		for i := range resourceList.Items {
 			// set the annotation on each resource item
-			if err := items[i].PipeE(yaml.SetAnnotation("value", value)); err != nil {
-				return nil, err
+			err := resourceList.Items[i].PipeE(yaml.SetAnnotation("value", value))
+			if err != nil {
+				return err
 			}
 		}
-		return items, nil
+		return nil
 	})
 	cmd.Flags().StringVar(&value, "value", "", "annotation value")
 

kyaml/fn/framework/example_test.go

@@ -89,15 +89,17 @@ functionConfig:
 func ExampleCommand_modify() {
 	// configure the annotation value using a flag parsed from
 	// ResourceList.functionConfig.data.value
+	resourceList := framework.ResourceList{}
 	var value string
-	cmd := framework.Command(nil, func(items []*yaml.RNode) ([]*yaml.RNode, error) {
-		for i := range items {
+	cmd := framework.Command(&resourceList, func() error {
+		for i := range resourceList.Items {
 			// set the annotation on each resource item
-			if err := items[i].PipeE(yaml.SetAnnotation("value", value)); err != nil {
-				return nil, err
+			err := resourceList.Items[i].PipeE(yaml.SetAnnotation("value", value))
+			if err != nil {
+				return err
 			}
 		}
-		return items, nil
+		return nil
 	})
 	cmd.Flags().StringVar(&value, "value", "", "annotation value")
 
@@ -164,12 +166,13 @@ func ExampleCommand_generateReplace() {
 	functionConfig := &ExampleServiceGenerator{}
 
 	// function implementation -- generate a Service resource
-	cmd := framework.Command(functionConfig, func(nodes []*yaml.RNode) ([]*yaml.RNode, error) {
+	resourceList := &framework.ResourceList{FunctionConfig: functionConfig}
+	cmd := framework.Command(resourceList, func() error {
 		var newNodes []*yaml.RNode
-		for i := range nodes {
-			meta, err := nodes[i].GetMeta()
+		for i := range resourceList.Items {
+			meta, err := resourceList.Items[i].GetMeta()
 			if err != nil {
-				return nil, err
+				return err
 			}
 
 			// something we already generated, remove it from the list so we regenerate it
@@ -178,7 +181,7 @@ func ExampleCommand_generateReplace() {
 				meta.APIVersion == "v1" {
 				continue
 			}
-			newNodes = append(newNodes, nodes[i])
+			newNodes = append(newNodes, resourceList.Items[i])
 		}
 
 		// generate the resource
@@ -188,9 +191,11 @@ metadata:
   name: %s
 `, functionConfig.Spec.Name))
 		if err != nil {
-			return nil, err
+			return err
 		}
-		return append(newNodes, n), nil
+		newNodes = append(newNodes, n)
+		resourceList.Items = newNodes
+		return nil
 	})
 
 	// for testing purposes only -- normally read from stdin when Executing
@@ -341,12 +346,13 @@ func ExampleCommand_generateUpdate() {
 	functionConfig := &ExampleServiceGenerator{}
 
 	// function implementation -- generate or update a Service resource
-	cmd := framework.Command(functionConfig, func(nodes []*yaml.RNode) ([]*yaml.RNode, error) {
+	resourceList := &framework.ResourceList{FunctionConfig: functionConfig}
+	cmd := framework.Command(resourceList, func() error {
 		var found bool
-		for i := range nodes {
-			meta, err := nodes[i].GetMeta()
+		for i := range resourceList.Items {
+			meta, err := resourceList.Items[i].GetMeta()
 			if err != nil {
-				return nil, err
+				return err
 			}
 
 			// something we already generated, reconcile it to make sure it matches what
@@ -356,9 +362,9 @@ func ExampleCommand_generateUpdate() {
 				meta.APIVersion == "v1" {
 				// set some values
 				for k, v := range functionConfig.Spec.Annotations {
-					err := nodes[i].PipeE(yaml.SetAnnotation(k, v))
+					err := resourceList.Items[i].PipeE(yaml.SetAnnotation(k, v))
 					if err != nil {
-						return nil, err
+						return err
 					}
 				}
 				found = true
@@ -366,7 +372,7 @@ func ExampleCommand_generateUpdate() {
 			}
 		}
 		if found {
-			return nodes, nil
+			return nil
 		}
 
 		// generate the resource if not found
@@ -375,18 +381,18 @@ kind: Service
 metadata:
   name: %s
 `, functionConfig.Spec.Name))
+		if err != nil {
+			return err
+		}
 		for k, v := range functionConfig.Spec.Annotations {
 			err := n.PipeE(yaml.SetAnnotation(k, v))
 			if err != nil {
-				return nil, err
+				return err
 			}
 		}
-		nodes = append(nodes, n)
-		if err != nil {
-			return nil, err
-		}
+		resourceList.Items = append(resourceList.Items, n)
 
-		return nodes, nil
+		return nil
 	})
 
 	// for testing purposes only -- normally read from stdin when Executing
@@ -445,25 +451,26 @@ functionConfig:
 // If any Deployments do not contain spec.replicas, then the function will return results
 // which will be set on ResourceList.results
 func ExampleCommand_validate() {
-	cmd := framework.Command(nil, func(nodes []*yaml.RNode) ([]*yaml.RNode, error) {
+	resourceList := &framework.ResourceList{}
+	cmd := framework.Command(resourceList, func() error {
 		// validation results
 		var validationResults []framework.Item
 
 		// validate that each Deployment resource has spec.replicas set
-		for i := range nodes {
+		for i := range resourceList.Items {
 			// only check Deployment resources
-			meta, err := nodes[i].GetMeta()
+			meta, err := resourceList.Items[i].GetMeta()
 			if err != nil {
-				return nil, err
+				return err
 			}
 			if meta.Kind != "Deployment" {
 				continue
 			}
 
 			// lookup replicas field
-			r, err := nodes[i].Pipe(yaml.Lookup("spec", "replicas"))
+			r, err := resourceList.Items[i].Pipe(yaml.Lookup("spec", "replicas"))
 			if err != nil {
-				return nil, err
+				return err
 			}
 
 			// check replicas not specified
@@ -481,11 +488,14 @@ func ExampleCommand_validate() {
 			})
 		}
 
-		// framework will only consider results an error if it has at least 1 item
-		return nodes, framework.Result{
-			Name:  "replicas-validator",
-			Items: validationResults,
+		if len(validationResults) > 0 {
+			resourceList.Result = &framework.Result{
+				Name:  "replicas-validator",
+				Items: validationResults,
+			}
 		}
+
+		return resourceList.Result
 	})
 
 	// for testing purposes only -- normally read from stdin when Executing

kyaml/fn/framework/framework.go

@@ -163,20 +163,18 @@ func (r *ResourceList) Write() error {
 
 // Command returns a cobra.Command to run a function.
 //
-// The cobra.Command will use a ResourceList to Read() the input, run the provided function,
-// and Write() the output.
-//
-// If functionConfig is non-nil, the ResourceList.functionConfig will be unmarshalled into it.
+// The cobra.Command will use the provided ResourceList to Read() the input,
+// run the provided function, and then Write() the output.
 //
 // The returned cobra.Command will have a "gen" subcommand which can be used to generate
 // a Dockerfile to build the function into a container image
 //
 //		go run main.go gen DIR/
-func Command(functionConfig interface{}, function Function) cobra.Command {
+func Command(resourceList *ResourceList, function Function) cobra.Command {
 	cmd := cobra.Command{}
 	AddGenerateDockerfile(&cmd)
 	cmd.RunE = func(cmd *cobra.Command, args []string) error {
-		err := execute(function, functionConfig, cmd)
+		err := execute(resourceList, function, cmd)
 		if err != nil {
 			fmt.Fprintf(cmd.ErrOrStderr(), "%v", err)
 		}
@@ -209,38 +207,20 @@ CMD ["function"]
 	cmd.AddCommand(gen)
 }
 
-func execute(function Function, functionConfig interface{}, cmd *cobra.Command) error {
-	rl := ResourceList{
-		FunctionConfig: functionConfig,
-		Flags:          cmd.Flags(),
-		Writer:         cmd.OutOrStdout(),
-		Reader:         cmd.InOrStdin(),
-	}
+func execute(rl *ResourceList, function Function, cmd *cobra.Command) error {
+	rl.Reader = cmd.InOrStdin()
+	rl.Writer = cmd.OutOrStdout()
+	rl.Flags = cmd.Flags()
 
 	if err := rl.Read(); err != nil {
 		return err
 	}
 
-	// run the function implementation
-	var err error
-	rl.Items, err = function(rl.Items)
-
-	// set the ResourceList.results for validating functions
-	var result *Result
-	if err != nil {
-		if val, ok := err.(Result); ok {
-			rl.Result = &val
-		} else {
-			return errors.Wrap(err)
-		}
-	}
+	retErr := function()
 
 	if err := rl.Write(); err != nil {
 		return err
 	}
 
-	if result != nil && result.ExitCode() != 0 {
-		return errors.Wrap(err)
-	}
-	return nil
+	return retErr
 }

kyaml/fn/framework/framework_test.go

@@ -11,7 +11,6 @@ import (
 
 	"github.com/stretchr/testify/assert"
 	"sigs.k8s.io/kustomize/kyaml/fn/framework"
-	"sigs.k8s.io/kustomize/kyaml/yaml"
 )
 
 func TestCommand_dockerfile(t *testing.T) {
@@ -22,9 +21,9 @@ func TestCommand_dockerfile(t *testing.T) {
 	defer os.RemoveAll(d)
 
 	// create a function
-	cmd := framework.Command(nil, func(nodes []*yaml.RNode) ([]*yaml.RNode, error) {
-		return nil, nil
-	})
+
+	resourceList := &framework.ResourceList{}
+	cmd := framework.Command(resourceList, func() error { return nil })
 
 	// generate the Dockerfile
 	cmd.SetArgs([]string{"gen", d})

kyaml/fn/framework/types.go

@@ -11,7 +11,7 @@ import (
 
 // Function defines a function which mutates or validates a collection of configuration
 // To create a structured validation result, return a Result as the error.
-type Function func(nodes []*yaml.RNode) ([]*yaml.RNode, error)
+type Function func() error
 
 // Result defines a function result which will be set on the emitted ResourceList
 type Result struct {