RAW POST using cURL in PHP

I just found the solution, kind of answering to my own question in case anyone else stumbles upon it.

$ch = curl_init();

curl_setopt($ch, CURLOPT_URL,            "http://url/url/url" );
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1 );
curl_setopt($ch, CURLOPT_POST,           1 );
curl_setopt($ch, CURLOPT_POSTFIELDS,     "body goes here" ); 
curl_setopt($ch, CURLOPT_HTTPHEADER,     array('Content-Type: text/plain')); 

$result = curl_exec($ch);

Implementation with Guzzle library:

use GuzzleHttp\Client;
use GuzzleHttp\RequestOptions;

$httpClient = new Client();

$response = $httpClient->post(
    'https://postman-echo.com/post',
    [
        RequestOptions::BODY => 'POST raw request content',
        RequestOptions::HEADERS => [
            'Content-Type' => 'application/x-www-form-urlencoded',
        ],
    ]
);

echo(
    $response->getBody()->getContents()
);

PHP CURL extension:

$curlHandler = curl_init();

curl_setopt_array($curlHandler, [
    CURLOPT_URL => 'https://postman-echo.com/post',
    CURLOPT_RETURNTRANSFER => true,

    /**
     * Specify POST method
     */
    CURLOPT_POST => true,

    /**
     * Specify request content
     */
    CURLOPT_POSTFIELDS => 'POST raw request content',
]);

$response = curl_exec($curlHandler);

curl_close($curlHandler);

echo($response);

Source code