<?php
namespace Magleaks\Catalog\Setup;

use Magento\Catalog\Model\Product;
use Magento\Catalog\Model\Product\Type;
use Magento\Catalog\Model\Resource\Eav\Attribute;
use Magento\Eav\Setup\EavSetupFactory;
use Magento\Framework\Setup\InstallDataInterface;
use Magento\Framework\Setup\ModuleContextInterface;
use Magento\Framework\Setup\ModuleDataSetupInterface;

/**
 * Class InstallData
 *
 * @package Magleaks\Catalog\Setup
 */
class InstallData implements InstallDataInterface
{
    /**
     * @var \Magento\Eav\Setup\EavSetupFactory
     */
    private $eavSetupFactory;
    /**
     * @param EavSetupFactory $eavSetupFactory
     */
    public function __construct(EavSetupFactory $eavSetupFactory)
    {
        $this->eavSetupFactory = $eavSetupFactory;
    }
    /**
     * @param ModuleDataSetupInterface $setup
     * @param ModuleContextInterface   $context
     */
    public function install(ModuleDataSetupInterface $setup, ModuleContextInterface $context)
    {
        /** @var EavSetup $eavSetup */
        $eavSetup = $this->eavSetupFactory->create(['setup' => $setup]);
        $productTypes = [
            Type::TYPE_SIMPLE,
            Type::TYPE_VIRTUAL,
        ];
        $productTypes = join(',', $productTypes);
        $eavSetup->addAttribute(
            Product::ENTITY,
            'on_sale',
            [
                'type'                    => 'int',
                'label'                   => 'Sale',
                'input'                   => 'boolean',
                'sort_order'              => 50,
                'global'                  => Attribute::SCOPE_WEBSITE,
                'user_defined'            => true,
                'required'                => false,
                'used_in_product_listing' => true,
                'apply_to'                => $productTypes,
                'group'                   => 'General',
                'unique'                  => false,
                'visible_on_front'        => false,
                'searchable'              => false,
                'filterable'              => false,
                'comparable'              => false,
                'visible'                 => true,
                'backend'                 => '',
                'frontend'                => '',
                'class'                   => '',
                'source'                  => '',
                'default'                 => '',
            ]
        );
    }
}

bin/magento setup:upgrade