I have to create app where each user has his own database, can login on his own subdomain, but all users use the same API endpoints (Lambda functions).
API is in Node.js, Frontend in Angular 7.
Is it feasible? Can you give me instruction how to configure AWS to it?
Lambda is just like any other programing environment so you can definitely restrict users to their own data in a multi-tenant application. How depends on many things including the database you are using.
I’m not aware of any tutorials because it depends on the application requirements and architectual decisions. I can tell you that I’ve done it using AppSync + Lambda + DynamoDB. The same general principle applies as doing it any other environment: store the tenant ID with your data and write queries so people can only fetch data from tenants they have access to.