AWS上でブラウザリダイレクトを実装するパターンを制約とともにまとめてみた

$ curl -sI "http://s3-redirect-p1-xxxxxxxxxxxx.s3-website-ap-northeast-1.amazonaws.com"

HTTP/1.1 301 Moved Permanently
x-amz-id-2: nxQXuPL5giHzh0Ho0758OTOtAXcHLFPD4NKS2VMuVcleeUtCC8XzuW9vCAwjrQ/G/zwoelp4Mi03xp0TGInAX4YhywA0fkka
x-amz-request-id: JKW0MZK18VTNP3ZE
Date: Mon, 02 Mar 2026 05:17:04 GMT
Location: https://www.example.com/
Content-Length: 0
Server: AmazonS3
Cf-Team: 2d4e9394a40001e429ae141400000001

curl  "https://s3-redirect-p1-xxxxxxxxxxxx.s3-website-ap-northeast-1.amazonaws.com"

# 実行に数秒かかる上に、レスポンスなし

[
    {
        "Condition": {
            "KeyPrefixEquals": "docs/"
        },
        "Redirect": {
            "ReplaceKeyPrefixWith": "documents/"
        }
    }
]

$ curl -sI http://alb-redirect-demo-xxxxxxxxxx.ap-northeast-1.elb.amazonaws.com

HTTP/1.1 301 Moved Permanently
Server: awselb/2.0
Date: Mon, 02 Mar 2026 08:00:14 GMT
Content-Type: text/html
Content-Length: 134
Connection: keep-alive
Location: https://www.example.com:443/
Cf-Team: 2d4f28fb9a0001e42937c48400000001

$ curl -sI http://alb-redirect-demo-xxxxxxxxxx.ap-northeast-1.elb.amazonaws.com/docs/guide

HTTP/1.1 301 Moved Permanently
Server: awselb/2.0
Date: Mon, 02 Mar 2026 08:01:28 GMT
Content-Type: text/html
Content-Length: 134
Connection: keep-alive
Location: http://alb-redirect-demo-xxxxxxxxxx.ap-northeast-1.elb.amazonaws.com:80/documents/
Cf-Team: 2d4f2a1ee50001e42938843400000001

async function handler(event) {
    var request = event.request;
    var uri = request.uri;

    // /redirect → https://www.example.com/ に 301 リダイレクト
    if (uri === '/redirect') {
        return {
            statusCode: 301,
            statusDescription: 'Moved Permanently',
            headers: {
                location: { value: 'https://www.example.com/' }
            }
        };
    }

    // /external/* → https://external-site.example.com に 301 リダイレクト
    if (uri.indexOf('/external/') === 0) {
        var newPath = uri.replace('/external', '');
        return {
            statusCode: 301,
            statusDescription: 'Moved Permanently',
            headers: {
                location: { value: 'https://external-site.example.com' + newPath }
            }
        };
    }

    // その他はオリジン（S3）にそのまま転送
    return request;
}

$ curl -sI "https://xxxxxxxxxxxxxe.cloudfront.net/redirect"

HTTP/1.1 301 Moved Permanently
Server: CloudFront
Date: Tue, 10 Mar 2026 05:44:47 GMT
Content-Length: 0
Connection: keep-alive
Location: https://www.example.com/
X-Cache: FunctionGeneratedResponse from cloudfront
Via: 1.1 d148799fe664d933eb8d6afff0dbacb8.cloudfront.net (CloudFront)
X-Amz-Cf-Pop: KIX82-P3
X-Amz-Cf-Id: ESM4blbUySorJ8LW9OuBSrCXIet1xZxqdFVCWsbGaNz_InVmXnAPxQ==

$ curl -sI "https://xxxxxxxxxxxxxe.cloudfront.net/external/some/path"

HTTP/1.1 301 Moved Permanently
Server: CloudFront
Date: Tue, 10 Mar 2026 05:44:47 GMT
Content-Length: 0
Connection: keep-alive
Location: https://external-site.example.com/some/path
X-Cache: FunctionGeneratedResponse from cloudfront
Via: 1.1 1955a35a2db92d617ec0931122fe6a84.cloudfront.net (CloudFront)
X-Amz-Cf-Pop: KIX82-P3
X-Amz-Cf-Id: aInNueoDPEI1samsu5L8ArUkOXPXIZ3tHNLysvVlqKu9fNdYNFgdNg==

def handler(event, context):
    request = event['Records'][0]['cf']['request']
    uri = request['uri']

    # /redirect → https://www.example.com/ に 301 リダイレクト
    if uri == '/redirect':
        return {
            'status': '301',
            'statusDescription': 'Moved Permanently',
            'headers': {
                'location': [{'key': 'Location', 'value': 'https://www.example.com/'}]
            }
        }

    # /external/* → https://external-site.example.com に 301 リダイレクト
    if uri.startswith('/external/'):
        new_path = uri.replace('/external', '', 1)
        return {
            'status': '301',
            'statusDescription': 'Moved Permanently',
            'headers': {
                'location': [{'key': 'Location', 'value': 'https://external-site.example.com' + new_path}]
            }
        }

    # その他はオリジン（S3）にそのまま転送
    return request

$ curl -sI "https://xxxxxxxxxxxxxx.cloudfront.net/redirect"

HTTP/1.1 301 Moved Permanently
Content-Length: 0
Connection: keep-alive
Server: CloudFront
Date: Tue, 10 Mar 2026 06:49:52 GMT
Location: https://www.example.com/
X-Cache: Miss from cloudfront
Via: 1.1 7b6afd329ec93047d9d66526d7d0c22c.cloudfront.net (CloudFront)
X-Amz-Cf-Pop: KIX82-P4
X-Amz-Cf-Id: 4mLBz1GEN-yMCLuZJZhXN-GqshxWvScxGgL4rNWGfyXsU7sVj86Kjw==

$ curl -sI "https://xxxxxxxxxxxxxx.cloudfront.net/external/some/path"

HTTP/1.1 301 Moved Permanently
Content-Length: 0
Connection: keep-alive
Server: CloudFront
Date: Tue, 10 Mar 2026 06:49:52 GMT
Location: https://external-site.example.com/some/path
X-Cache: Miss from cloudfront
Via: 1.1 24dbe851fbf0a37d67de659f1f3828f6.cloudfront.net (CloudFront)
X-Amz-Cf-Pop: KIX82-P4
X-Amz-Cf-Id: KYgxTjt49CsWc0ZFCwJ8lYNT8w1GJmq85N67iFY8W3dmwSlmF4T48g==