Blog Post Related to the Repository

Link: https://medium.com/cp-massive-programming/gateway-pattern-introduction-on-the-bases-of-kong-gateway-e788e8c5662f

NestJs, Swagger, Swagger Stats and Kong Gateway

NestJs Swagger Documentation

The OpenAPI specification is a language-agnostic definition format used to describe RESTful APIs. Nest provides a dedicated module which allows generating such a specification by leveraging decorators.

https://docs.nestjs.com/openapi/introduction

Swagger Stats Documentation

swagger-stats traces REST API requests and responses in Node.js Microservices, and collects metrics per API Operation. swagger-stats detects API operations based on express routes. You may also provide Swagger (Open API) specification, and swagger-stats will match API requests with API Operations defined in swagger specification.

https://swaggerstats.io/guide/

Swagger Stats Grafana Dashboard

Simple Grafana Dashboard for swagger stats and its prometheus client.

https://grafana.com/grafana/dashboards/3091

Kong API Gateway

A lightweight API Gateway that lets you secure, manage, and extend APIs and microservices.

https://konghq.com/
https://docs.konghq.com/gateway/
https://hub.docker.com/_/kong

What speaks for Kong

• Easy to integrate into an existing system (e.g., db-less mode)
• No changes to existing services necessary
• Extendable with various plugins like Rate-limiting, OAuth 2.0, CORS, GraphQL Proxy Caching, and so on..
• Configurable via declarative config file, K8s definition, or API administration (e.g., POST methods to push config)
• Easy to monitor with Datadog, Prometheus, and so on..

Configuration example

This example shows a declarative configuration for a service integrated behind Kong

_format_version: "2.1"
_transform: true

services:
  - name: image-service
    url: http://image-service:3333
    routes:
      - name: image-service
        paths:
          - /image-service

Plugin example (Rate limiting)

Link: https://docs.konghq.com/hub/kong-inc/rate-limiting/

plugins:
  - name: rate-limiting
    service: image-service
    config:
      minute: 6 # The number of HTTP requests that can be made per minute
      policy: local

Docker-Compose example

kong:
  container_name: kong
  image: kong:2.5.0-alpine
  hostname: kong
  environment:
    KONG_DATABASE: 'off'
    KONG_PROXY_ACCESS_LOG: '/dev/stdout'
    KONG_ADMIN_ACCESS_LOG: '/dev/stdout'
    KONG_PROXY_ERROR_LOG: '/dev/stderr'
    KONG_ADMIN_ERROR_LOG: '/dev/stderr'
    KONG_ADMIN_LISTEN: "0.0.0.0:8001, 0.0.0.0:8444 ssl"
    KONG_DECLARATIVE_CONFIG: "/opt/kong/.config.yaml"
  command: "kong start"
  ports:
    - "8000:8000"
    - "8443:8443"
    - "8001:8001"
    - "8444:8444"
  volumes:
    - ./kong:/opt/kong

How Kong works in this project

• Kong is running in database-less mode (no Postgres or Cassandra is needed), so you configure Kong Gateway declaratively
• The Admin API is mostly read-only
• Kong configuration endpoint: http://localhost:8001/
• Kong service configuration endpoint: http://localhost:8001/services
• kong default route: http://localhost:8000
• Service endpoints through Gateway:

$ http://localhost:8000/image-service/api/#
$ http://localhost:8000/wine-maker/api/#

• Kong config file: ./kong/.config.yaml

NestJs Installation & Run

$ npm install

$ nx serve image-service
// open url http://localhost:3333/api/ for swagger API
// open url http://localhost:3333/swagger-stats/ for swagger stats
// prometheus-format metrics: http://localhost:3333/swagger-stats/metrics

$ nx serve wine-maker
// open url http://localhost:3334/api/ for swagger API
// open url http://localhost:3334/swagger-stats/ for swagger stats
// prometheus-format metrics: http://localhost:3334/swagger-stats/metrics

Docker Instruction

I have used Docker-Compose here to show in a simple way how to integrate Kong into your existing microservice landscape. You don't need to change any existing service to integrate Kong into your system.

Docker-Compose File

Run local instances

docker build . -t base-image:nx-base
docker-compose up

Build local instances

docker build . -t base-image:nx-base
docker-compose build