Improve functionRunner interface

go/fn/examples/data/runner-configmap-general.yaml

@@ -0,0 +1,15 @@
+apiVersion: config.kubernetes.io/v1
+kind: ResourceList
+items:
+  - apiVersion: v1
+    kind: Service
+    metadata:
+      name: example
+functionConfig:
+  apiVersion: v1
+  kind: ConfigMap
+  metadata:
+    name: runner-fn-config
+  data:
+    project-id: kpt-dev
+    managed-by: kpt

go/fn/examples/data/runner-configmap.yaml

@@ -0,0 +1,15 @@
+apiVersion: config.kubernetes.io/v1
+kind: ResourceList
+items:
+  - apiVersion: v1
+    kind: Service
+    metadata:
+      name: example
+functionConfig:
+  apiVersion: v1
+  kind: ConfigMap
+  metadata:
+    name: customConfig
+  data:
+    owner: kpt
+    org: google

go/fn/examples/data/setlabels-resourcelist.yaml → go/fn/examples/data/runner-customFnConfig.yaml

@@ -7,6 +7,8 @@ items:
       name: example
 functionConfig:
   apiVersion: fn.kpt.dev/v1alpha1
-  kind: SetLabels
+  kind: CustomFnConfig
   metadata:
-    name: setlabel-fn-config
+    name: runner-fn-config
+  owner: kpt
+  org: google

go/fn/examples/example_asmain_runner_test.go

@@ -19,43 +19,108 @@ import (
 	"github.com/GoogleContainerTools/kpt-functions-sdk/go/fn"
 )
 
+var _ fn.Runner = &CustomFnConfig{}
+
+type CustomFnConfig struct {
+	Owner string
+	Org   string
+}
+
+// Run is the main function logic.
+// `ctx` provides easy methods to add info, error or warning result to `ResourceList.Results`.
+// `items` is parsed from the STDIN "ResourceList.Items".
+// `functionConfig` is from the STDIN "ResourceList.FunctionConfig". The value is parsed from a `CustomFnConfig` type
+// "owner" and "org" field.
+func (r *CustomFnConfig) Run(ctx *fn.Context, functionConfig *fn.KubeObject, items fn.KubeObjects) {
+	for _, o := range items {
+		o.SetName(r.Owner)
+		o.SetNamespace(r.Org)
+	}
+	ctx.ResultInfo("updated namespace and name", nil)
+}
+
+// This example uses a CustomFnConfig object, which implements `Runner.Run` methods.
+func Example_asMainCustomFnConfig() {
+	file, _ := os.Open("./data/runner-customFnConfig.yaml")
+	defer file.Close()
+	os.Stdin = file
+
+	if err := fn.AsMain(&CustomFnConfig{}); err != nil {
+		os.Exit(1)
+	}
+	// Output:
+	// apiVersion: config.kubernetes.io/v1
+	// kind: ResourceList
+	// items:
+	// - apiVersion: v1
+	//   kind: Service
+	//   metadata:
+	//     name: kpt
+	//     namespace: google
+	// functionConfig:
+	//   apiVersion: fn.kpt.dev/v1alpha1
+	//   kind: CustomFnConfig
+	//   metadata:
+	//     name: runner-fn-config
+	//   owner: kpt
+	//   org: google
+	// results:
+	// - message: updated namespace and name
+	//   severity: info
+}
+
+func Example_asMainConfigMap() {
+	file, _ := os.Open("./data/runner-configmap.yaml")
+	defer file.Close()
+	os.Stdin = file
+
+	if err := fn.AsMain(&CustomFnConfig{}); err != nil {
+		os.Exit(1)
+	}
+	// Output:
+	// apiVersion: config.kubernetes.io/v1
+	// kind: ResourceList
+	// items:
+	// - apiVersion: v1
+	//   kind: Service
+	//   metadata:
+	//     name: kpt
+	//     namespace: google
+	// functionConfig:
+	//   apiVersion: v1
+	//   kind: ConfigMap
+	//   metadata:
+	//     name: customConfig
+	//   data:
+	//     owner: kpt
+	//     org: google
+	// results:
+	// - message: updated namespace and name
+	//   severity: info
+}
+
 var _ fn.Runner = &SetLabels{}
 
 type SetLabels struct {
-	Labels map[string]string `json:"labels,omitempty"`
+	Data map[string]string
 }
 
 // Run is the main function logic.
 // `ctx` provides easy methods to add info, error or warning result to `ResourceList.Results`.
 // `items` is parsed from the STDIN "ResourceList.Items".
-// `functionConfig` is from the STDIN "ResourceList.FunctionConfig". The value has been assigned to the r.Labels
-//  the functionConfig is validated to have kind "SetLabels" and apiVersion "fn.kpt.dev/v1alpha1"
-func (r *SetLabels) Run(ctx *fn.Context, functionConfig *fn.KubeObject, items []*fn.KubeObject) {
+// `functionConfig` is from the STDIN "ResourceList.FunctionConfig". The value is parsed from a `ConfigMap` type
+// "data" field.
+func (r *SetLabels) Run(ctx *fn.Context, functionConfig *fn.KubeObject, items fn.KubeObjects) {
 	for _, o := range items {
-		for k, newLabel := range r.Labels {
-			o.SetLabel(k, newLabel)
+		for k, v := range r.Data {
+			o.SetLabel(k, v)
 		}
 	}
 	ctx.ResultInfo("updated labels", nil)
 }
 
-// This example uses a SetLabels object, which implements `Runner.Run` methods.
-//
-// The input from ./data/setlabels-resourcelist.yaml:
-// apiVersion: config.kubernetes.io/v1
-// kind: ResourceList
-// items:
-//   - apiVersion: v1
-//     kind: Service
-//     metadata:
-//       name: example
-// functionConfig:
-//   apiVersion: fn.kpt.dev/v1alpha1
-//   kind: SetLabels
-//   metadata:
-//     name: setlabel-fn-config
-func Example_asMain() {
-	file, _ := os.Open("./data/setlabels-resourcelist.yaml")
+func Example_asMain_configMapData() {
+	file, _ := os.Open("./data/runner-configmap-general.yaml")
 	defer file.Close()
 	os.Stdin = file
 
@@ -70,11 +135,17 @@ func Example_asMain() {
 	//   kind: Service
 	//   metadata:
 	//     name: example
+	//     labels:
+	//       project-id: kpt-dev
+	//       managed-by: kpt
 	// functionConfig:
-	//   apiVersion: fn.kpt.dev/v1alpha1
-	//   kind: SetLabels
+	//   apiVersion: v1
+	//   kind: ConfigMap
 	//   metadata:
-	//     name: setlabel-fn-config
+	//     name: runner-fn-config
+	//   data:
+	//     project-id: kpt-dev
+	//     managed-by: kpt
 	// results:
 	// - message: updated labels
 	//   severity: info

go/fn/functionrunner.go

@@ -15,5 +15,5 @@
 package fn
 
 type Runner interface {
-	Run(context *Context, functionConfig *KubeObject, items []*KubeObject)
+	Run(context *Context, functionConfig *KubeObject, items KubeObjects)
 }

go/fn/runnerProcessor.go

@@ -17,6 +17,7 @@ package fn
 import (
 	"fmt"
 	"reflect"
+	"strings"
 )
 
 type runnerProcessor struct {
@@ -39,9 +40,19 @@ func (r *runnerProcessor) config(ctx *Context, o *KubeObject) {
 		data := o.NestedStringMapOrDie("data")
 		fnRunnerElem := reflect.ValueOf(r.fnRunner).Elem()
 		for i := 0; i < fnRunnerElem.NumField(); i++ {
-			if fnRunnerElem.Field(i).Kind() == reflect.Map {
-				fnRunnerElem.Field(i).Set(reflect.ValueOf(data))
-				break
+			switch fnRunnerElem.Field(i).Kind() {
+			case reflect.String:
+				for k, v := range data {
+					lowerKey := strings.ToLower(k)
+					if lowerKey == strings.ToLower(fnRunnerElem.Type().Field(i).Name) {
+						fnRunnerElem.Field(i).SetString(v)
+						break
+					}
+				}
+			case reflect.Map:
+				if "Data" == fnRunnerElem.Type().Field(i).Name {
+					fnRunnerElem.Field(i).Set(reflect.ValueOf(data))
+				}
 			}
 		}
 	case o.IsGVK("fn.kpt.dev", "v1alpha1", fnName):