301でリダイレクトするためのLambda関数

main.go

package main

import (
	"bufio"
	"fmt"
	"net/http"
	"net/url"
	"strings"

	"github.com/aws/aws-lambda-go/events"
	"github.com/aws/aws-lambda-go/lambda"
	"golang.org/x/net/html"
)

// リライトルールを実装（panicしても最悪/blogは返す）
func rewrite(path string) (result string) {
	fmt.Printf("try rewrite = %v\n", path)

	result = "/blog"
	defer func() {
		if err := recover(); err != nil {
			fmt.Println("recover:", err)
			result = "/blog"
		}
	}()

	// root や /@user もしくは日本語URLは無視
	if strings.Contains(path, "/@") ||
		strings.Contains(path, "%") ||
		"" == path ||
		"/" == path {
		return
	}

	// pathを念の為正規化して、ルールに従ってリダイレクト先作成を試みる
	u, err := url.Parse("https://blog.r3it.com" + path)
	if err != nil {
		fmt.Println(err.Error())
	}
	normalPath := u.Path
	if !strings.Contains(normalPath, "-") {
		return
	}

	// - で区切られてる想定されたパスか？
	slug := normalPath[0:strings.LastIndex(normalPath, "-")]
	result = "/blog" + slug
	fmt.Printf("  rewrite <%s> to <%s>\n", path, result)

	return
}

func handler(request events.APIGatewayProxyRequest) (events.APIGatewayProxyResponse, error) {
	fmt.Printf(" : %#v\n", request)
	hostHeader := request.Headers["Host"]

	if strings.Contains(hostHeader, "seminar") {
		return events.APIGatewayProxyResponse{
			StatusCode: 301,
			Headers: map[string]string{
				"Location": "https://www.r3it.com/seminarevent",
			},
		}, nil
	}

	return events.APIGatewayProxyResponse{
		StatusCode: 301,
		Headers: map[string]string{
			"Location": "https://www.r3it.com" + rewrite(request.Path),
		},
	}, nil
}

func main() {
	lambda.Start(handler)
}