add vanity url code

cmd/m3o-go-url/main.go

@@ -0,0 +1,55 @@
+// Copyright 2017 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.
+
+package main
+
+import (
+	"io/ioutil"
+	"log"
+	"net/http"
+	"os"
+)
+
+func main() {
+	var configPath string
+	switch len(os.Args) {
+	case 1:
+		configPath = "vanity.yaml"
+	case 2:
+		configPath = os.Args[1]
+	default:
+		log.Fatal("usage: m3o-go-url [CONFIG]")
+	}
+	vanity, err := ioutil.ReadFile(configPath)
+	if err != nil {
+		log.Fatal(err)
+	}
+	h, err := newHandler(vanity)
+	if err != nil {
+		log.Fatal(err)
+	}
+	http.Handle("/", h)
+
+	port := os.Getenv("PORT")
+	if port == "" {
+		port = "8080"
+	}
+	if err := http.ListenAndServe(":"+port, nil); err != nil {
+		log.Fatal(err)
+	}
+}
+
+func defaultHost(r *http.Request) string {
+	return r.Host
+}