Apply setters README and godocs

functions/go/Makefile

@@ -122,4 +122,5 @@ func-push:
 generate:
 	GO111MODULE=on go get -v github.com/GoogleContainerTools/kpt/mdtogo
 	$(GOBIN)/mdtogo search-replace search-replace/generated --license=none --strategy=cmdDocs
+	$(GOBIN)/mdtogo apply-setters apply-setters/generated --license=none --strategy=cmdDocs
 

functions/go/apply-setters/README.md

@@ -0,0 +1,94 @@
+# apply-setters
+
+### Overview
+
+<!--mdtogo:Short-->
+
+Apply setter values on resources fields. May set either the complete or partial field value.
+
+<!--mdtogo-->
+
+Setters provide a solution for template-free setting of field values. They are a
+safer alternative to other substitution techniques which do not have the context
+of the structured data. Setters may be invoked to modify the configuration
+using `apply-setters` function to set values.
+
+### Synopsis
+
+<!--mdtogo:Long-->
+
+```
+kpt fn eval apply-setters:VERSION [DIR] -- [setter_name=setter_value]
+```
+
+Data model
+
+1. Fields reference setters specified as line comments -- e.g.
+
+```
+    # kpt-set: replicas
+```
+
+2. Input values to setters are provided as key-value pairs -- e.g.
+
+```
+    kpt fn eval apply-setters:unstable -- replicas=3
+```
+
+Control flow
+
+1. Read the package resources.
+2. Locate all fields which reference the setter and change their values.
+3. Write the modified resources back to the package.
+
+<!--mdtogo-->
+
+### Examples
+
+<!--mdtogo:Examples-->
+
+Let's start with the input resources
+
+```yaml
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: the-map # kpt-set: ${name}
+data:
+  some-key: some-value
+---
+apiVersion: v1
+kind: MyKind
+metadata:
+  name: ns
+environments: # kpt-set: ${env}
+  - dev
+  - stage
+```
+
+Invoke apply-setters function on the input resources
+
+```
+kpt fn eval apply-setters:unstable -- 'name=my-map' 'env=[prod, dev]'
+```
+
+The resources are transformed to
+
+```yaml
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: my-map # kpt-set: ${name}
+data:
+  some-key: some-value
+---
+apiVersion: v1
+kind: MyKind
+metadata:
+  name: ns
+environments: # kpt-set: ${env}
+  - prod
+  - dev
+```
+
+<!--mdtogo-->

functions/go/apply-setters/main.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"os"
 
+	"github.com/GoogleContainerTools/kpt-functions-catalog/functions/go/apply-setters/generated"
 	"sigs.k8s.io/kustomize/kyaml/fn/framework"
 	kyaml "sigs.k8s.io/kustomize/kyaml/yaml"
 )
@@ -25,64 +26,16 @@ func main() {
 		return nil
 	})
 
-	cmd.Long = usage()
+	cmd.Short = generated.ApplySettersShort
+	cmd.Long = generated.ApplySettersLong
+	cmd.Example = generated.ApplySettersExamples
+
 	if err := cmd.Execute(); err != nil {
 		fmt.Println(err)
 		os.Exit(1)
 	}
 }
 
-func usage() string {
-	return `Apply setter values to resource fields with setter references.
-
-Example:
-
-Here is an example resource config to start with
-
-apiVersion: v1
-kind: Deployment
-metadata:
-  name: my-deployment
-spec:
-  replicas: 1 # kpt-set: ${replicas}
-
-Use ConfigMap to configure the 'apply-setters' function. The desired setter values 
-are provided as key-value pairs using data field where key is the name of the 
-setter(as seen in the reference comments) and value is the new desired value for 
-the tagged field
-
-apiVersion: v1
-kind: ConfigMap
-metadata:
-  name: my-config
-data:
-  replicas: '3'
-
-Invoking apply-setters function would apply the changes to resource configs
-
-apiVersion: v1
-kind: Deployment
-metadata:
-  name: my-deployment
-spec:
-  replicas: 3 # kpt-set: ${replicas}
-
-
-Values to array setters must be array nodes wrapped into strings. Here is the
-example config to apply array setters.
-
-apiVersion: v1
-kind: ConfigMap
-metadata:
-  name: my-config
-data:
-  projectId: my-project
-  environments: |
-    - dev
-    - staging
-`
-}
-
 // getSetters retrieve the setters from input config
 func getSetters(fc interface{}) (ApplySetters, error) {
 	var fcd ApplySetters