Upload a file to Slack API with PHP Guzzle

slack-file-upload.php

<?php

require_once "../vendor/autoload.php";

use GuzzleHttp\Client;

/**
 * Notes:
 *
 * Tested with guzzlehttp/guzzle version 7.3
 * See https://api.slack.com/methods/files.upload for details on how to generate a token
 *
 */

$fileName = '';
$filePath = '';
$slacktoken = ''; // See https://api.slack.com/tokens; The token will need file.read and file.write permissions

$client = new Client();
$apiUrl = 'https://slack.com/api/files.upload';

$client = new Client();
$request = $client->post( $apiUrl, [
    'headers' => ['Authorization' => 'auth_trusted_header'],
    'multipart' => [
        [
            'name' => 'token',
            'contents' => $slacktoken,
        ],
        [
            'name'     => 'file',
            'contents' => fopen($filePath, 'r'),
            'filename' => $fileName
        ],
        [
            'name' => 'channels',
            'contents' => '#general'
        ],
        [
            'name' => 'initial_comment',
            'contents' => 'File Uploaded'
        ]
    ]
]);

var_dump($request->getBody()->getContents());