Is there a hint to actually upload image to S3 bucket from a given url ? Trying with

$this->fileSystemService->writeStream($fileSystemStreamTransfer, $stream);

I guess I will have to download temporarily the image and do a kind of fopen to create the $stream argument ?

fopen supports opening remote urls if not deactivated for security reasons. So you do not need to download the image to a local file first but could open a stream for the remote url and pass this into

writeStream

I am using this method , but still i get the error

private function determineSource($url)
{
    // Use the contents of a file as the data source.
    if (is_string($url)) {
        $source= Psr7\Utils::tryFopen($url, 'r');
    }

//    Create a source stream.
//    $stream = Psr7\Utils::streamFor($source);
//    if (!$stream->isReadable()) {
//        throw new IAE('Source stream must be readable.');
//    }

    return $source;
}

$stream = $this->determineSource($url);

// Upload file
$this->fileSystemService->writeStream($fileSystemStreamTransfer, $stream);