How to run an app with a custom base image (Docker)?

Basically, you build your base image using a Dockerfile. This image must live on Docker Hub and be publicly readable. (This means they should not contain any secrets.). Once you’ve built your base image and pushed it to Docker Hub, specify it in your settings.json.

The paragraph above is just an overview of the process, and you must follow the full documentation with all the steps in our documentation: https://cloud-guide.meteor.com/custom-base-images.html