API gateway using Spring Cloud Gateway

API gateway is an API management tool that sits between a client and a collection of backend services.

Why use an API gateway?

Most enterprise APIs are deployed via API gateways. It’s common for API gateways to handle common tasks that are used across a system of API services, such as user authentication, rate limiting, and statistics.

• Authentication and authorization. A gateway is your first line of defense against potential attackers that can perform basic security functions: antivirus scanning, token translation, decryption and encryption, validation, and many more.

• Log tracing and aggregation. A gateway keeps detailed audit logs used for debugging, reporting, and analytics.

• Rate limiting. A gateway enforces policies against resource overuse (either accidental or deliberate) and allows you to configure API invocation at runtime, so the service is consumed only at the required rate.

• You may have adopted a microservices architecture, in which case a single request could require calls to dozens of distinct applications.

• Over time you’ll add some new API services and retire others, but your clients will still want to find all your services in the same place.

Dependency version

Java 21

Spring Boot 3.2.1

WebFlux 6.1.2

Spring Cloud 2023.0.0

Spring Gateway 4.1.0

H2 Database: 2.2.224

The router after starting will create on H2 the table 'endpoint' and insert follow row.

CREATE TABLE endpoint (
  id BIGINT auto_increment  PRIMARY KEY,
  uri_request VARCHAR(500) NOT NULL,
  url_destination VARCHAR(500) NOT NULL,
  enable BOOLEAN DEFAULT FALSE,
  http_method VARCHAR(4) DEFAULT NULL
);
  
INSERT INTO endpoint VALUES (1, '/blog/api/user', 'http://localhost:8080/blog/api/user', TRUE, 'GET' ); 

Testing:

Example: Request with uri_request "http://localhost:8888/blog/api/user"

will route to url_destination= "http://localhost:8080/blog/api/user"

Send request

http://localhost:8888/blog/api/user [GET] 

The request will route to the microservice running on port 8080.

     http://localhost:8080/blog/api/user [GET]