Configure APT repositories using DEB package

Question

I am using a MySQL server and have created a custom .deb package that depends on (and basically wraps) MySQL and performs some customizations in postinst maintainer script.

Now I want to upgrade MySQL to the latest version, which is not provided by APT by default, and requires downloading and installing a package that configures APT to supply later versions of MySQL.

My questions is how can I do this using still a .deb package to do all of that automatically?

I have looked into using pre-depend field of control file to install the configuration package fully before the MySQL wrapper package, but I still need to do apt-get update in the middle, which is not possible to do from the maintainer scripts.

I am trying to stick to debian package format, and not create any custom scripts (outside of maintainer scripts or other options supported by the .deb format)

Answer 1

Thanks to @muru for confirming my suspicion.

Indeed we have ended up using a two phased approach, where apt setup requirements are gathered and installed, and only then installing the main package.