为什么我的PHP脚本间歇性地无法通过FTP上传文件？

Question

I wrote a PHP script to export orders from an e-commerce store, save them in an XML file and then copy them to a remote FTP folder. Another company monitor that FTP folder for new files and use them to fulfil the orders.

For some reason the script only uploads the file some of the time and I am finding debugging / getting to the bottom of this very difficult. This is the main part of the offending script:

if ($ftp_conn = ftp_connect($ftp_server)) {
    if ($login = ftp_login($ftp_conn, $ftp_user, $ftp_pass)) {

        $filename = time() . '-orders.xml';
        ftp_pasv($ftp_conn, true);

        if (ftp_put($ftp_conn, $filename, $xmlPath, FTP_ASCII)) {
            $logString .= ' - Successfully run';
            ftp_close($ftp_conn);
        } else {
            $logString .= ' - Failed to upload file';
            $error = error_get_last();
            $logString .= ' - ' . $error['message'];
            ftp_close($ftp_conn);
        }
    } else {
        $logString .= ' - Failed to log in to server';
        ftp_close($ftp_conn);
    }
} else {
    $logString .= ' - Failed to connect to server';
};

I save the $logString variable to a text file. The only error I actually see reported is:

ftp_put(): Type set to A

I can't find anything online about what that means or if it should be causing the problem.

The FTP connection log is no help either. This is all you see when it fails to run:

"PASS (hidden)" 230 -
"TYPE A" 200 -

Sometimes it works, sometimes it doesn't. There's no obvious pattern to when it fails. Large and small XML files have worked and failed.

Apparently the server can handle 3 simultaneous connections and in theory there should only ever be 2 so I can't see that being the issue.

Is the PHP script OK and, if so, is there anything else I can do to try and log what happens when the file fails to upload?

Answer 1

Whether this is considered a fix or a bodge job, I will leave up to you.

My best guess is there is an issue with the 1and1 FTP server I am connecting to as the script above worked without issue on a different server.

I tried switching the ftp_put mode to FTP_BINARY but it made no difference.

I got around the issue by looping the whole function until it was completed successfully. Ie:

$uploaded = false;
$tries = 0;
$filename = time() . '-orders.xml';

while (!$uploaded && $tries <= 5) {
    $tries++;
    if ($ftp_conn = ftp_connect($ftp_server)) {
        if ($login = ftp_login($ftp_conn, $ftp_user, $ftp_pass)) {
            $logString .= ' - Attempt ' . $tries;

            ftp_pasv($ftp_conn, true);
            ftp_set_option($ftp_conn, FTP_TIMEOUT_SEC, 120);

            if (ftp_put($ftp_conn, $filename, $xmlPath, FTP_BINARY)) {
                $logString .= ' - Successfully run';
                $uploaded = true;
                ftp_close($ftp_conn);
            } else {
                $logString .= ' - Failed to upload file';
                $error = error_get_last();
                $logString .= ' - ' . $error['message'];
                ftp_close($ftp_conn);
            }
        } else {
            $logString .= ' - Failed to log in to server';
            ftp_close($ftp_conn);
        }
    } else {
        $logString .= ' - Failed to connect to server';
    };
};

I capped $tries at 5 in case something was genuinely wrong. The CRON job runs often enough that if it doesn't work one time it can work another.

So far this has worked well. The most tries needed to upload a file has been 4 and at no point has it completely failed to upload the file. So it's working and I can relax a bit.