MICROSERVICES BASIS [Gateway approach]

Tech stack

• fastapi - endpoints implementation
• psql - main DB
• sqlalchemy - ORM
• alembic - migrations
• fastapi-jwt-auth - JWT Authentication
• aiohttp - Asynchronous requests between microservices

Functionality

Provided repo implements bare minimum functionality to build up microservice oriented project, that sticks to gateway approach. It includes:

• centralized jwt-authentication between microservices
• response post-processing
• CRUD for Users application

Existing functionality can be scaled by adding new services and scaling the gateway itself. Gateway microservice can be scaled by adding:

• response caching
• request pre-processing/data normalization
• response post-processing
• response composition from multiple services
• internal-use authentication/authorization
• etc.

Gateway approach

Little synopsis on gateway approach can be found here

Current implementation of gateway microservice is decently simple. It knows response schemas, paths and expected status codes of all other microservices. It implements custom wrapper on FastAPI route, that gives opportunity to centralize all requests and bind endpoints. Implementation of custom route is based on aiohttp core. So the gateway just decomposes received request and composes new one with custom additions and adjustments. Finally, it makes asynchronous request to internally available microservice and receives its response, if there is one, if not gateway handles this situation by returning 503 - Service unavailable. Response received from service can be post processed if needed.

Gateway itself implements centralized JWT authentication by providing endpoints to fetch access and refresh tokens. In addition it has an endpoint to refresh expired access-token.

How to use

docker-compose build
docker-compose up

There is PGAdmin on :5050 port for convenience of monitoring the data. API docs are on 0.0.0.0:8001/docs or 0.0.0.0:8001/redoc

Testing

Link to postman collection for testing each existing endpoint: https://www.getpostman.com/collections/ad9858b74404041fb58f. It consists of JSON content that needs to be imported to your Postman application.