Add version converting binary

cmd/kube-version-change/version.go

+/*
+Copyright 2014 Google Inc. All rights reserved.
+
+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.
+*/
+
+// kube-version-change is a simple utility for converting a
+// kubernetes object into a different api version.
+package main
+
+import (
+	"bytes"
+	"encoding/json"
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+	"runtime"
+
+	"github.com/GoogleCloudPlatform/kubernetes/pkg/api"
+	_ "github.com/GoogleCloudPlatform/kubernetes/pkg/api/v1beta1"
+	_ "github.com/GoogleCloudPlatform/kubernetes/pkg/api/v1beta2"
+	_ "github.com/GoogleCloudPlatform/kubernetes/pkg/api/v1beta3"
+
+	"github.com/ghodss/yaml"
+	flag "github.com/spf13/pflag"
+)
+
+var (
+	inputSource   = flag.StringP("input", "i", "-", "Input source; '-' means stdin")
+	outputDest    = flag.StringP("output", "o", "-", "Output destination; '-' means stdout")
+	rewrite       = flag.StringP("rewrite", "r", "", "If nonempty, use this as both input and output.")
+	outputVersion = flag.StringP("out-version", "v", "v1beta3", "Version to convert input to")
+)
+
+// isYAML determines whether data is JSON or YAML formatted by seeing
+// if it will parse as json.
+func isYAML(data []byte) bool {
+	var unused interface{}
+	if err := json.Unmarshal(data, &unused); err != nil {
+		return true
+	}
+	return false
+}
+
+func main() {
+	runtime.GOMAXPROCS(runtime.NumCPU())
+	flag.Parse()
+
+	if *rewrite != "" {
+		*inputSource = *rewrite
+		*outputDest = *rewrite
+	}
+
+	var in io.Reader
+	if *inputSource == "-" {
+		in = os.Stdin
+	} else {
+		f, err := os.Open(*inputSource)
+		if err != nil {
+			log.Fatalf("Couldn't open %q: %q", *inputSource, err)
+		}
+		defer f.Close()
+		in = f
+	}
+
+	data, err := ioutil.ReadAll(in)
+	if err != nil {
+		log.Fatalf("Couldn't read from input: %q", err)
+	}
+
+	obj, err := api.Scheme.Decode(data)
+	if err != nil {
+		log.Fatalf("Couldn't decode input: %q", err)
+	}
+
+	outData, err := api.Scheme.EncodeToVersion(obj, *outputVersion)
+	if err != nil {
+		log.Fatalf("Failed to encode to version %q: %q", *outputVersion, err)
+	}
+
+	if isYAML(data) {
+		outData, err = yaml.JSONToYAML(outData)
+		if err != nil {
+			log.Fatalf("Failed to convert to YAML: %q", err)
+		}
+	} else if true {
+		// TODO: figure out if input JSON was pretty.
+		var buf bytes.Buffer
+		err = json.Indent(&buf, outData, "", "  ")
+		if err != nil {
+			log.Fatalf("Failed to indent JSON: %q", err)
+		}
+		outData = buf.Bytes()
+	}
+
+	var out io.Writer
+	if *outputDest == "-" {
+		out = os.Stdout
+	} else {
+		f, err := os.Create(*outputDest)
+		if err != nil {
+			log.Fatalf("Couldn't open %q: %q", *outputDest, err)
+		}
+		defer f.Close()
+		out = f
+	}
+
+	if _, err = out.Write(outData); err != nil {
+		log.Fatalf("Failed to write: %q", err)
+	}
+}