PHP SFTP with some additional flavor text and error handling

sftp_test.php

<?php 

$hostname = 'host.example.com';
$port = 22;
$username =  'your_username';
$ssh_key = './ssh/id_rsa';
$ssh_pubkey = './ssh/id_rsa.pub';
$src_file = 'testupload.txt';
$dest_file = "remoteDirectory/{$src_file}";

ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL);

try {
    $conn = ssh2_connect($hostname, $port);
    if (!$conn) {
        throw new Exception("Connection failed!");
    }

    if (!ssh2_auth_pubkey_file($conn, $username, $ssh_pubkey, $ssh_key)) {
        throw new Exception("Authentication failed!");
    }
    echo "Authentication successful!" . PHP_EOL;

    $sftp_conn = ssh2_sftp($conn);
    if (!$sftp_conn) {
        throw new Exception("Could not initialize SFTP session.");
    }

    $sftp_stream = fopen("ssh2.sftp://$sftp_conn/{$dest_file}", 'w');
    if (!$sftp_stream) {
        throw new Exception("Could not open remote file: $dest_file");
    }

    $data_to_send = file_get_contents($src_file);
    if ($data_to_send === false) {
        throw new Exception("Could not open local file: $src_file.");
    }

    if (fwrite($sftp_stream, $data_to_send) === false) {
        throw new Exception("Could not send data from file: $src_file.");
    }

    echo "File {$src_file} uploaded successfully to {$dest_file}!" . PHP_EOL;

} catch (Exception $e) {
    error_log('Exception: ' . $e->getMessage() . PHP_EOL);
} finally {
    if (isset($sftp_stream) && is_resource($sftp_stream)) {
        fclose($sftp_stream);
    }
}
?>