Spring Cloud Gateway Versioning

Purpose

• a demonstration of setting up a Spring Cloud Gateway that supports dynamic versioning
• submodules contain the various supporting components including
  • spring cloud config server setup
  • spring openfeign client
  • sample server code

This set of repos will demonstrate

• feign client making http requests to a Spring Cloud Gateway
• Spring Cloud Gateway receiving routing configuration from Spring Cloud Config
• ability to - at runtime - refresh the routes and pick up new version
• ability to configure routes to perform redirect

Versioning

The mechanism of versioning is in URL. This example exposes a simple service GET /api/service/version which responds with the deployed server version (e.g. 1.0). When a client calls /api/service/version on the gateway, it responds with a 302 to the versioned URL /api/v1/service. When the backend server starts up a new version of the application (1.1), the route is updated via Spring Cloud Config. Now, when a client issues GET /api/service/version to the gateway, it receives a 302 /api/v1.1/service.

If a client wants to continue consuming an explicit version of the api (e.g. 1.0), the gateway still supports direct access of /api/v1/service.

Management Steps

To manage backend versions, the following steps would be performed;

1. deploy a new instance of the service side-by-side with the current version
2. update the config/gateway-default.yml with the additional route, changing the root URL to redirect to the latest version
3. invoke /actuator/bus-refresh on the gateway to pick up the new configuration

Running

1. clone this repo
2. git submodule init
3. git submodule update
4. build the config server

   cd config-server
   gradle bootJar
   

5. run the config server java -jar build/libs/[server].jar &
6. build the backend server

   cd ../sample-server
   gradle bootJar
   

7. run two versions of the sample server

   java -Dserver.port=9001 -Dapp.version=1.1 -jar build/libs/[server].jar &
   java -jar build/libs/[server].jar &
   

8. build the client

   cd ../sample-client
   gradle bootJar
   

9. run the client

   java -jar build/libs/[server].jar &
   

10. test URLs

• GET http://localhost:8001/client/service should respond with 1.1
• GET http://localhost:8000/api/service should respond with 1.1
• GET http://localhost:8000/api/v1/service should respond with 1.0
• GET http://localhost:8000/api/v1.1/service should respond with 1.1

RabbitMQ Docker

docker run -d --hostname my-rabbit --name some-rabbit -p 15672:15672 -p 5672:5672 rabbitmq:3-management