Streaming a response in CakePHP - php

Question

I want CakePHP to stream a download to the browser. The content of the stream is served via an API.
So, CakePHP makes a request to that API, gets a response with a file and must stream this response to the browser.
This is what I got so far:
public function getDownload() {
// do other things
$http = new Client([
'headers' => [
'accept' =>'application/octet-stream'
]
]);
$response = $http->get($this->url,[]);
// first try
// $stream = new CallbackStream(function () use ($response) {
// return $response;
// });
// $response = $response->withBody($stream);
// second try
// $stream = new CallbackStream($http->get($this->url,[])->getData());
// $response = $response->withBody($stream);
return $response;
}
With this setup I can download small files. The reason I need a stream is, because the API could send files up to 10GB. My guess is, that with $http->get CakePHP stores the whole response in memory. Thats why I'm getting a memory exhausted error.
I know I'm lacking a bit of understanding here. Any help is appreciated :)

Answer 1

Finally I found a solution:
public function getDownload($url) {
$opts = array(
'http'=>array(
'method'=>"GET",
'header'=>"accept: application/octet-stream\r\n"
)
);
$context = stream_context_create($opts);
$response = new Response();
$file = fopen($url, 'r',false, $context);
$stream = new CallbackStream(function () use ($file) {
rewind($file);
fpassthru($file);
fclose($file);
});
$response = $response->withBody($stream);
return $response;
}