example fetch function using php

fetch-function.php

<?php
/* from StackOverflow: https://stackoverflow.com/a/52662522/1345527 */
function fetch(string $method, string $url, string $body, array $headers = []) {
    $context = stream_context_create([
        "http" => [
            // http://docs.php.net/manual/en/context.http.php
            "method"        => $method,
            "header"        => implode("\r\n", $headers),
            "content"       => $body,
            "ignore_errors" => true,
        ],
    ]);

    $response = file_get_contents($url, false, $context);

    /**
     * @var array $http_response_header materializes out of thin air
     */

    $status_line = $http_response_header[0];

    preg_match('{HTTP\/\S*\s(\d{3})}', $status_line, $match);

    $status = $match[1];

    if ($status !== "200") {
        throw new RuntimeException("unexpected response status: {$status_line}\n" . $response);
    }

    return $response;
}

// usage
$response = fetch(
    "POST",
    "http://example.com/",
    json_encode([
        "foo" => "bar",
    ]),
    [
        "Content-Type: application/json",
        "X-API-Key: 123456789",
    ]
);