simple-kong-docker-API-gateway

A basic API gateway serving both internal and services - built with Kong, Docker, & PostgreSQL

Setup

• Install Docker from here if you don't have it already

• Install docker-compose as well

apt install docker-compose

• clone the repo

git clone https://github.com/rafian-git/simple-kong-docker-API-gateway.git

Run the project

• change directory into project folder

cd simple-kong-docker-API-gateway

• start the project running docker-composer

docker-compose up -d

Note that the -d flag will running the containers as a background process. The compose file does 4 things:

1. Creates PostgreSQL container as a backend data store (configuration info) for Kong .
2. Creates an ephemeral to initialize the Postgres database.
3. Builds a container for the Hello world Node.js microservice.
4. Runs the Kong API Gateway as a container.

Verify

• Verify by checking running containers

docker ps

• Verify if the Kong Gateway and Admin API are responding:

curl http://localhost:8000
curl http://localhost:8001

• To get the list of all available Admin API endpoints:

curl http://localhost:8001/endpoints

Creating an external Service Proxy

Now, create a local service and name it anything with hyphen separated words like your-service-name. We will forward our requests to our external service(hosted in another remote machine). For the sake of this project we will consider a public API as our external service. You'll find a lot of public APIs to play with here or here. We will be using catfact.ninja in this project. This is a two part process as both the service and then the route must be established like so:

curl -i -X POST --url http://localhost:8001/services/ --data 'name=your-service-name' --data 'url=https://catfact.ninja/'
curl -i -X POST --url http://localhost:8001/services/your-service-name/routes --data 'hosts[]=your-service-name'

You can now test both the plubic API and the proxied service using cURL:

curl https://catfact.ninja/breeds
curl http://localhost:8000/breeds --header 'your-service-name'

Both will return the same result if you've done it right.

you can directly hit http://server-public-ip-address:8000/breeds instead of using curl if you're running it on a virtual server with public IP.

Setting up an internal Service

The Hello World NodeJS app

Following the recipe above, we can build an endpoint for the Node.js microservice:

curl -i -X POST --url http://localhost:8001/services/ --data 'name=hello-world-service' --data 'url=http://kong-app:3000'
curl -i -X POST --url http://localhost:8001/services/hello-world-service/routes --data 'hosts[]=hello-world-service'

Remember that this service is running in the kong-app container and is exposed to the isolated Docker network via port 3000 but callers cannot access it without going through the API gateway. We can reach the hello-world-service using the Host header just like the previous one:

curl http://localhost:8000 --header 'Host: hello-world-service'

Use the below endpoint to see a list of all the services enabled so far:

curl http://localhost:8001/services

Enable Rate Limiting

Adding rate limiting (a maximum of 5 requests per minute in this case) to a service is as simple as running a single command:

curl -X POST http://localhost:8001/services/hello-world-service/plugins/ --data "name=rate-limiting" --data "config.minute=5" --data "config.policy=local"

If you hit the hello-world-service endpoint again, you will see additional headers in the response indicating the rate limit. Hit it more than 5 times to check if the plugin is working

curl http://localhost:8000 --header 'Host: hello-world-service'

You'll find a lot of ready plugins here

Add Authorization

Key-based authorization can be add to the hello-world-service endpoint by enabling the key-auth plugin, creating a user (QA in this example) and then providing the access key:

curl -i -X POST --url http://localhost:8001/services/hello-world-service/plugins/ --data 'name=key-auth'
curl -i -X POST --url http://localhost:8001/consumers/ --data "username=QA"
curl -i -X POST --url http://localhost:8001/consumers/QA/key-auth/ --data 'key=Hello_Kong!'

Test the time-service endpoint both with and without specifying an API key:

curl http://localhost:8000 --header 'Host: hello-world-service'
curl http://localhost:8000 --header 'Host: hello-world-service' --header "apikey: Hello_Kong!"

Conclusion

& you're done! Find out more if you want - Docs