nginx.conf

        location / {
                set $aws_access_key_id "";
                set $aws_secret_access_key "";
                set $bucket_name "bucket";
                mruby_set_code $date "Nginx::Time.http_time(Nginx::Time.time)";
                mruby_set_code $authorization '

                        content_md5 = ""
                        content_type = ""

                        request = Nginx::Request.new
                        var = Nginx::Var.new
                        string_to_sign = request.method + "\n" +
                                         content_md5 + "\n" +
                                         content_type + "\n" +
                                         var.date + "\n" +
                                         "/" + var.bucket_name + request.uri
                        hmac_sha1 = Nginx::Digest.hmac_sha1(string_to_sign, var.aws_secret_access_key)
                        "AWS " + var.aws_access_key_id + ":" + Nginx::Base64.encode(hmac_sha1)
                ';

                resolver 192.168.1.1;

                proxy_set_header Host $bucket_name.example.com;
                proxy_set_header Date $date;
                proxy_set_header Authorization $authorization;
                proxy_pass http://$bucket_name.example.com:8080$uri;
        }