在没有数据库的 JHipster 微服务架构中创建网关

Question

I am trying out JHipster based on the supported Microservice architecture. I have created a Registry, Gateway, and a Microservice (based on JWT authentication) as described in documentation and everything works. However I am not sure why a Gateway in JHispter need to have a database. Questions that are still unanswered for me: 1- Why does a Gateway need a database? In which scenarios would you create a Gateway with/without a database? 2- Do the Gateway and Microservice use the same database? Or should they use separate database instances?

Answer 1

1) A gateway using JWT or OAuth2 auth types need a database to store users and their account details. A gateway using UAA auth type does not need a database, because the UAA microservice handles users and authentication.

2) Gateways and microservices should use their own database instances. You can use the same database instance in dev , but in prod each should have their own.

You can generate a docker-compose or kubernetes config for your gateway/microservices with the JHipster subgenerators, and in the generated YML files you will see each app has its own database instance.

Answer 2

Ok, I did a bit more research on JHipster-Gateway and the inner workings of it. Below is a summary, related to my question:

1- A Gateway using a JWT or Oauth2 type only needs a database if the User related entities and backend code are also generated in the Gateway codebase. This is the case for a default JHipster Gateway, but does not have to be like this. As indicated in JHipster documentation a JHipster Gateway is actually a monolithic application and can be used as a monolithic application:

You will have the choice either to generate an new entity normally (a gateway is also a standard JHipster application, so this would work like for a monolith application), or use an existing JHipster configuration from a microservice.

When you create a JHipster Gateway, it creates the User entity related backend in Gateway codebase as default. But you can choose to have all the Backend code (including User) be placed/generated in Microservice codebase.

In such case there is no need of a database in JHipster Gateway application. Gateway working purely as a gateway to pass requests to microservices only needs to have the /api configurations properly set.

In the default case of a JHipster Gateway the User entity backend code is also generated in Gateway part, that is the reason why a database is needed. But you can move the backend code to Microservice and replace it by a proper /api configuration.