APP_KEY generation command for Lumen, adapted from Illuminate\Foundation\Console\KeyGenerateCommand

KeyGenerateCommand.php

<?php

namespace App\Console\Commands;

use Illuminate\Console\Command;

class KeyGenerateCommand extends Command
{
    /**
     * The name and signature of the console command.
     *
     * @var string
     */
    protected $signature = 'key:generate {--show : Display the key instead of modifying files}';

    /**
     * The console command description.
     *
     * @var string
     */
    protected $description = 'Set the application key';

    /**
     * Execute the console command.
     */
    public function fire()
    {
        $key = $this->generateRandomKey();

        if ($this->option('show')) {
            return $this->line('<comment>' . $key . '</comment>');
        }

        $this->setKeyInEnvironmentFile($key);

        $this->info("Application key [$key] set successfully.");
    }

    /**
     * Set the application key in the environment file.
     *
     * @param string $key
     */
    protected function setKeyInEnvironmentFile($key)
    {
        $path = base_path('.env');

        file_put_contents($path, preg_replace(
            '/APP_KEY=.*/',
            'APP_KEY=' . $key,
            file_get_contents($path)
        ));
    }

    /**
     * Generate a random key for the application.
     *
     * @return string
     */
    protected function generateRandomKey()
    {
        return 'base64:' . base64_encode(random_bytes(32));
    }
}