file_get_contents() gets 403 from api.github.com every time - php

Question

I call myself an experienced PHP developer, but this is one drives me crazy. I'm trying to get release informations of a repository for displaying update-warnings, but I keep returning 403 errors. For simplifying it I used the most simple usage of GitHubs API: GET https://api.github.com/zen. It is kind of a hello world.
This works
directly in the browser
with a plain curl https://api.github.com/zen in a terminal
with a PHP-Github-API-Class like php-github-api
This works not
with a simple file_get_contents()from a PHP-Skript
This is my whole simplified code:
<?php
$content = file_get_contents("https://api.github.com/zen");
var_dump($content);
?>
The browser shows Warning: file_get_contents(https://api.github.com/zen): failed to open stream: HTTP request failed! HTTP/1.0 403 Forbidden, the variable $content is a boolean and false.
I guess I'm missing some sort of http-header-fields, but neither can I find those informations in the API-Docs, nor uses my terminal curl-call any special header files and works.

Answer 1

This happens because GitHub requires you to send UserAgent header. It doesn't need to be anything specific. This will do:
$opts = [
'http' => [
'method' => 'GET',
'header' => [
'User-Agent: PHP'
]
]
];
$context = stream_context_create($opts);
$content = file_get_contents("https://api.github.com/zen", false, $context);
var_dump($content);
The output is:
string(35) "Approachable is better than simple."