Running Laravel Cron Jobs in Docker with FrankenPHP

Yesterday I spent some time digging into how cron jobs work in Laravel. There are two fairly straightforward commands involved:

php artisan schedule:run
php artisan schedule:work

The idea is that the first command should be placed into the actual system crontab in whatever environment runs your backend (or any environment that has the required environment variables and access to the database).

Your crontab entry usually looks something like this:

* * * * * cd /path-to-your-project && php artisan schedule:run >> /dev/null 2>&1

This means the command runs every minute.

The idea behind this approach is to delegate the scheduling logic to PHP and Laravel. When this command runs, Laravel checks app/Console/Kernel.php for registered scheduled tasks. They typically look something like this:

$schedule->command('emails:send Taylor --force')->daily();

In this case, ->daily() means the command is expected to run once per day.

What does schedule:work do?

According to the documentation, the second command (schedule:work) is intended only for local development.

All it really does is run schedule:run every minute, but implemented in PHP using an infinite loop.

You can see the original implementation here:

https://github.com/laravel/framework/pull/34618/files

Modern Laravel versions have a much more complex implementation, but that initial pull request still gives a very clear understanding of how the mechanism works.

My setup: Docker + FrankenPHP

I run my backend application in Docker using docker-compose. The base image is dunglas/frankenphp.

Here’s how the service is defined in docker-compose.yml:

backend-cron:
  restart: unless-stopped
  build:
    target: dev
  volumes:
    - .:/app
  command: "frankenphp php-cli artisan schedule:work"
  healthcheck:
    disable: true
  env_file:
    .env

Every minute I was getting the same error:

backend-cron-1  | 2025-12-09T14:54:00.043306279Z sh: 1: : Permission denied
backend-cron-1  | 2025-12-09T14:55:00.041940906Z sh: 1: : Permission denied

At first, based on past experience, I assumed the script simply didn't have permission to write to the filesystem. This is a common Laravel issue when running inside Docker, usually related to the storage and bootstrap/cache directories.

But that wasn’t the case here.

The actual problem

It turned out that FrankenPHP cannot spawn subprocesses in this setup for some reason.

I tried playing around with setcap in the Docker image, but eventually gave up and just wrote a simple bash script that replicates what schedule:work does:

#!/bin/sh
set -e

echo "Starting schedule loop..."

while true; do
    # Wait until the start of the next minute
    sleep $((60 - $(date +%S)))

    # Run the scheduler
    frankenphp php-cli artisan schedule:run
done

Thoughts on FrankenPHP

Up until this point, I hadn't experienced any issues with FrankenPHP. It really worked as a drop-in replacement for the images I used before.

I haven't tried worker mode yet mostly because I expect it will require quite a bit of tweaking in the application itself to get everything running properly.