This pattern is common for background workers too, such as running gunicorn + celery in separate containers (Python tools) but the same image is used for both. You can change the CMD at runtime by overwriting it (for example the `command` property in Docker Compose and Kubernetes).

This avoids needing to hack around things at the Docker level to install an init system and it gives you a way to split things out at runtime so you individually scale and log them as needed.

It does mean a change in your app would restart nginx since the image would change for both but this isn't that big of a deal. If that was a deal breaker then you could create separate images for each one to still avoid an init system running in your container.