Router Assisted Service Discovery

Light-router is a service that provides consumers with another option to do service discovery if they cannot leverage client module provided by light-4j.

There are two ways to deploy light-router, and it is highly recommended for the client to own the instance of light-router.

For demo purposes, the light-router will be deployed in Kubernetes cluster master node as it has a static IP address. By following the steps below, you should have a router instance up and running and connect to multiple instances of API A in the Kubernetes cluster. Communication between API A, B, C, and D is handled with the client module inside each API.

Environment

The light-router will be deployed to the sandbox which is our development Kubernetes cluster master node.

Config

All configurations can be found at https://github.com/networknt/light-config-test/tree/master/light-router/cloud/config

Start

To start the server there is a docker-compose file in https://github.com/networknt/light-config-test/tree/master/light-router/cloud

The content of the docker-compose file:

version: '2'

services:

  light-router:
    image:  networknt/light-router:latest
    networks:
    - localnet
    ports:
    - 8080:8080
    volumes:
    - ./config:/config

#
# Networks
#
networks:
    localnet:
        # driver: bridge
        external: true

You must start the docker-compose at light-config-test/tree/master/light-router/cloud folder.

docker-compose up -d

Test

Before we start using the light-router, let’s make sure that we can access the reference APIs.

Go to the consul server http://38.113.162.50:8500/ to find an instance of API A. Here is an example.

curl -k https://38.113.162.51:2406/v1/data

And the following result should be expected.

["API D: Message 1 from port 7444","API D: Message 2 from port 7444","API B: Message 1","API B: Message 2","API C: Message 1","API C: Message 2","API A: Message 1","API A: Message 2"]

Now let’s access the router instance with the following command line.

curl -k -H "service_id: com.networknt.apia-1.0.0" https://38.113.162.50:8080/v1/data

And the result is:

["API D: Message 1 from port 7444","API D: Message 2 from port 7444","API B: Message 1","API B: Message 2","API C: Message 1","API C: Message 2","API A: Message 1","API A: Message 2"]

Summary

Light-router is an infrastructure service that can assist internal clients, and is not built on top of Java 8 for service discovery and security. It also can act as an external access point for external client to access internal service. In this case, it is playing a role of distributed API gateway.

All previous steps with Consul discovery are based on a dockerized consul instance with http connections. In production, we need to have a consul cluster and https needs to be enabled. In the next step, we are going to explore the Consul cluster with TLS connection.