auto retry database connection to different node laravel

AppServiceProvider.php

<?php

namespace App\Providers;

use DB;
use App\Setting;
use Illuminate\Support\ServiceProvider;

class AppServiceProvider extends ServiceProvider
{
    protected $pdo = null;
    
    public function boot()
    {
        // Note: getPdo() dont actually make database call
        // so it is efficient enough

        $this->setUpDBConnection();
        
        if ($this->pdo) {
            DB::select('SET SESSION TRANSACTION ISOLATION LEVEL READ COMMITTED');
        }

        if (config('database.connections.'.config('database.default'))['host'] == env('DB_HOST') &&
            env('DB_HOST_ORIGIN') == env('DB_HOST'))
        {
            return; // everything good
        }

        if (config('database.connections.'.config('database.default'))['host'] != env('DB_HOST')) {

            try {
                $this->pdo = DB::connection()->getPdo();
            } catch (\Exception $e) {
                return;
            }

            app('dotenvchanger')
                ->change('DB_HOST',
                    config('database.connections.'.config('database.default'))['host']
                );

            app('dotenvchanger')
                ->change('DB_LAST_CHANGE', now()->format('Y-m-d H:i:sO'));

            return;
        }
    }

    protected function setUpDBConnection()
    {
        try {

            $this->pdo = DB::connection()->getPdo();

            $this->shouldRepickDBConn();

        } catch (\Exception $e) {

            $failed_connections = [config('database.connections.'.config('database.default').'.host')];

            $backup_connections = json_decode(config('app.db_host_backup'));

            // random it
            shuffle($backup_connections);

            while ($backup_connection = array_pop($backup_connections)) {

                $conn_name = str_replace('.', '', $backup_connection);

                // create connection on the fly
                app('config')
                    ->set('database.connections.'.$conn_name,
                        [
                            'driver' => 'pgsql',
                            'host' => $backup_connection,
                            'port' => env('DB_PORT', '5432'),
                            'database' => env('DB_DATABASE', 'forge'),
                            'username' => env('DB_USERNAME', 'forge'),
                            'password' => env('DB_PASSWORD', ''),
                            'charset' => 'utf8',
                            'prefix' => '',
                            'prefix_indexes' => true,
                            'schema' => 'public',
                            'sslmode' => 'prefer',
                        ]
                    );

                app('config')->set('database.default', $conn_name);

                try {
                    $this->pdo = DB::connection()->getPdo();

                    $this->shouldRepickDBConn();

                    $this->reportFailedConnections($failed_connections);

                    break;
                } catch (\Exception $e2) {

                    $failed_connections[] = $backup_connection;

                    continue;
                }
            }
        }
    }

    protected function shouldRepickDBConn()
    {
        // repick database if this is plan restart/shutdown

        $host = config('database.connections.'.config('database.default'))['host'];

        $should_repick = ! Setting::whereK("db.{$host}")->whereV('up')->exists();

        if ($should_repick) {
            throw new \Exception("DB at {$host} shouldn't be pick, repicking..");
        }
    }

    protected function reportFailedConnections(Array $failed_connections)
    {
        $message = "Failed DB Connections on:";

        foreach ($failed_connections as $idx => $fc) {

            if ($idx != 0) {
                $message .= ",";
            }

            $message .= " $fc";
        }

        $default_conn = app('config')->get('database.default');

        app('sysnoti')->error($message);
    }
}