Function to create featured image in WP post

create_featured_image.php

<?php 

function create_featured_image($image_url, $post_id)
{
    $upload_dir = wp_upload_dir();
    $image_data = file_get_contents($image_url, true);
    if ($image_data === false) {
        $article_id = '0';
        $featured_image = 'logo.png';
        $image_url = 'img/' . $article_id . '/'. $featured_image;
        $image_data = file_get_contents($image_url);
    }
    $filename = basename($image_url);
    if (wp_mkdir_p($upload_dir['path'])) {
        $file = $upload_dir['path'] . '/' . $filename;
    } else {
        $file = $upload_dir['basedir'] . '/' . $filename;
    }
    file_put_contents($file, $image_data);

    $wp_filetype = wp_check_filetype($filename, null);
    $attachment = array(
        'post_mime_type' => $wp_filetype['type'],
        'post_title' => sanitize_file_name($filename),
        'post_content' => '',
        'post_status' => 'inherit'
    );
    $attach_id = wp_insert_attachment($attachment, $file, $post_id);
    require_once(ABSPATH . 'wp-admin/includes/image.php');
    $attach_data = wp_generate_attachment_metadata($attach_id, $file);
    $res1= wp_update_attachment_metadata($attach_id, $attach_data);
    $res2= set_post_thumbnail($post_id, $attach_id);
}