Revert "remove stale example"

functions/examples/Dockerfile

@@ -0,0 +1,15 @@
+# Copyright 2019 Google Inc.  All Rights Reserved.
+
+FROM golang:1.13-stretch
+ENV CGO_ENABLED=0
+WORKDIR /go/src/
+COPY go.mod .
+COPY go.sum .
+RUN go mod download
+COPY . .
+WORKDIR functions/examples
+RUN go build -v -o /usr/local/bin/config-function
+
+FROM alpine:latest
+COPY --from=0 /usr/local/bin/config-function /usr/local/bin/config-function
+CMD ["config-function"]

functions/examples/helloworld/function.go

@@ -0,0 +1,185 @@
+// Copyright 2019 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 helloworld
+
+import (
+	"fmt"
+
+	"github.com/GoogleContainerTools/kpt/functions/examples/util"
+	"sigs.k8s.io/kustomize/kyaml/kio"
+	"sigs.k8s.io/kustomize/kyaml/kio/filters"
+	"sigs.k8s.io/kustomize/kyaml/yaml"
+)
+
+const (
+	Kind       = "HelloWorld"
+	APIVersion = "examples.kpt.dev/v1alpha1"
+)
+
+var _ kio.Filter = &HelloWorldFunction{}
+
+// Filter returns a new HelloWorldFunction
+func Filter() kio.Filter {
+	return &HelloWorldFunction{}
+}
+
+// HelloWorldFunction implements the HelloWorld Function
+type HelloWorldFunction struct {
+	// Kind is the API name.  Must be HelloWorld.
+	Kind string `yaml:"kind"`
+
+	// APIVersion is the API version.  Must be examples.kpt.dev/v1alpha1
+	APIVersion string `yaml:"apiVersion"`
+
+	// Metadata defines instance metadata.
+	Metadata Metadata `yaml:"metadata"`
+
+	// Spec defines the desired declarative configuration.
+	Spec Spec `yaml:"spec"`
+}
+
+type Metadata struct {
+	// Name is the name of the HelloWorld Resources
+	Name string `yaml:"name"`
+
+	// Namespace is the namespace of the HelloWorld Resources
+	Namespace string `yaml:"namespace"`
+
+	// Labels are labels applied to the HelloWorld Resources
+	Labels map[string]string `yaml:"labels"`
+
+	// Annotations are annotations applied to the HelloWorld Resources
+	Annotations map[string]string `yaml:"annotations"`
+}
+
+type Spec struct {
+	Version string `yaml:"version"`
+
+	Port *int32 `yaml:"port"`
+
+	Replicas *int32 `yaml:"replicas"`
+
+	Selector map[string]string `yaml:"selector"`
+}
+
+func (f *HelloWorldFunction) init() error {
+	if f.Metadata.Name == "" {
+		return fmt.Errorf("must specify HelloWorld name")
+	}
+	if f.Spec.Version == "" {
+		f.Spec.Version = "0.1.0"
+	}
+	if f.Spec.Port == nil {
+		var p int32 = 80
+		f.Spec.Port = &p
+	}
+	if *f.Spec.Port <= 0 {
+		return fmt.Errorf("HelloWorld spec.port must be greater than 0")
+	}
+
+	if f.Spec.Replicas == nil {
+		var r int32 = 1
+		f.Spec.Replicas = &r
+	}
+	if *f.Spec.Replicas < 0 {
+		return fmt.Errorf("HelloWorld spec.replicas must be greater than or equal to 0")
+	}
+
+	if len(f.Spec.Selector) == 0 {
+		return fmt.Errorf("HelloWorld spec.selector must be specified")
+	}
+
+	if f.Metadata.Labels == nil {
+		f.Metadata.Labels = map[string]string{}
+	}
+
+	for k, v := range f.Spec.Selector {
+		f.Metadata.Labels[k] = v
+	}
+	return nil
+}
+
+func (f *HelloWorldFunction) Filter(inputs []*yaml.RNode) ([]*yaml.RNode, error) {
+	if err := f.init(); err != nil {
+		return nil, err
+	}
+	// override input values
+	r := util.MustParseAll(
+		util.Template{Input: f, Name: "helloworld-deployment", Template: helloWorldDeployment},
+		util.Template{Input: f, Name: "helloworld-service", Template: helloWorldService},
+	)
+	return filters.MergeFilter{}.Filter(append(inputs, r...))
+}
+
+const helloWorldDeployment = `
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: {{.Metadata.Name}}
+  {{- if .Metadata.Namespace}}
+  namespace: {{.Metadata.Namespace}}
+  {{- end}}
+  labels:
+  {{- range $k, $v := .Metadata.Labels}}
+    {{ $k }}: "{{ $v }}" 
+  {{- end}}
+spec:
+  replicas: {{ .Spec.Replicas }}
+  selector:
+    matchLabels:
+      {{- range $k, $v := .Spec.Selector}}
+      {{ $k }}: "{{ $v }}" 
+      {{- end}}
+  template:
+    metadata:
+      labels:
+        {{- range $k, $v := .Metadata.Labels}}
+        {{ $k }}: "{{ $v }}" 
+        {{- end}}
+    spec:
+      containers:
+      - name: helloworld-gke
+        image: gcr.io/kpt-dev/helloworld-gke:{{.Spec.Version}}
+        ports:
+        - name: http
+          containerPort: {{.Spec.Port}}
+        env:
+        - name: PORT
+          value: "{{.Spec.Port}}"
+`
+
+const helloWorldService = `
+apiVersion: v1
+kind: Service
+metadata:
+  name: {{.Metadata.Name}}
+  {{- if .Metadata.Namespace}}
+  namespace: {{.Metadata.Namespace}}
+  {{-  end}}
+  labels:
+  {{- range $k, $v := .Metadata.Labels}}
+    {{ $k }}: "{{ $v }}" 
+  {{- end}}
+spec:
+  type: LoadBalancer
+  selector:
+    {{- range $k, $v := .Spec.Selector}}
+    {{ $k }}: "{{ $v }}" 
+    {{- end}}
+  ports:
+  - protocol: TCP
+    port: {{.Spec.Port}}
+    targetPort: http
+`

functions/examples/main.go

@@ -0,0 +1,95 @@
+// Copyright 2019 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 main implements example kpt-functions
+package main
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"github.com/GoogleContainerTools/kpt/functions/examples/helloworld"
+	"github.com/spf13/cobra"
+	"sigs.k8s.io/kustomize/kyaml/kio"
+	"sigs.k8s.io/kustomize/kyaml/kio/filters"
+	"sigs.k8s.io/kustomize/kyaml/yaml"
+)
+
+func main() {
+	cmd := &cobra.Command{
+		Use:          "config-function",
+		SilenceUsage: true, // don't print usage on an error
+		RunE:         (&Dispatcher{}).RunE,
+	}
+	if err := cmd.Execute(); err != nil {
+		fmt.Fprintf(os.Stderr, "%v\n", err)
+		os.Exit(1)
+	}
+}
+
+// Dispatcher dispatches to the matching API
+type Dispatcher struct {
+	// IO hanldes reading / writing Resources
+	IO *kio.ByteReadWriter
+}
+
+func (d *Dispatcher) RunE(_ *cobra.Command, _ []string) error {
+	d.IO = &kio.ByteReadWriter{
+		Reader:                os.Stdin,
+		Writer:                os.Stdout,
+		KeepReaderAnnotations: true,
+	}
+
+	return kio.Pipeline{
+		Inputs: []kio.Reader{d.IO},
+		Filters: []kio.Filter{
+			d, // invoke the API
+			&filters.MergeFilter{},
+			&filters.FileSetter{FilenamePattern: filepath.Join("config", "%n.yaml")},
+			&filters.FormatFilter{},
+		},
+		Outputs: []kio.Writer{d.IO},
+	}.Execute()
+}
+
+// dispatchTable maps configFunction Kinds to implementations
+var dispatchTable = map[string]func() kio.Filter{
+	helloworld.Kind: helloworld.Filter,
+}
+
+func (d *Dispatcher) Filter(inputs []*yaml.RNode) ([]*yaml.RNode, error) {
+	// parse the API meta to find which API is being invoked
+	meta, err := d.IO.FunctionConfig.GetMeta()
+	if err != nil {
+		return nil, err
+	}
+
+	// find the implementation for this API
+	fn := dispatchTable[meta.Kind]
+	if fn == nil {
+		return nil, fmt.Errorf("unsupported API type: %s", meta.Kind)
+	}
+
+	// dispatch to the implementation
+	fltr := fn()
+
+	// initializes the object from the config
+	if err := yaml.Unmarshal([]byte(d.IO.FunctionConfig.MustString()), fltr); err != nil {
+		fmt.Fprintf(os.Stderr, "%v\n", err)
+		fmt.Fprintf(os.Stderr, "%s\n", d.IO.FunctionConfig.MustString())
+		os.Exit(1)
+	}
+	return fltr.Filter(inputs)
+}