You need to develop an small app that will handle authentication/authorization. Next time a feature comes you will implement that page in the new stack, the rest of production pages will still run in the old code base .
That's it.
A concurrent small migration to the new system without changing all the system at once.
Why it works? New systems often fail to encapsulate all the complexity. also two systems, duplicate your workload until you decide to drop new system because of the first statement.
Finally, get stats from nginx and figure out which routes aren't used in a month, try disabled some and see how much dead routes you can find and clean
That's it.
A concurrent small migration to the new system without changing all the system at once.
Why it works? New systems often fail to encapsulate all the complexity. also two systems, duplicate your workload until you decide to drop new system because of the first statement.
Finally, get stats from nginx and figure out which routes aren't used in a month, try disabled some and see how much dead routes you can find and clean