REST API Shopping Cart in GO and Kafka Consumer with Distributed Tracing and Metrics

Project Features

• There are to microservices,

  • cart_server : REST Api that adds items to the cart and emits one event in Kafka
  • cart_consumer : Kafka consumer listening to those events

• This project is an implementation of a Cart for an e-commerce and has 2 endpoints:

  • One to add items
  • One to retrieve the cart status

• The project has been implemented with DDD and Hexagonal Arquitecture, isolating domain, application and infrastructure

• In storage there is an inMemoryRepository for the two entities that could be easily modified to a Real DB

• The libraries used that are not from the standard library are:

  • Gorilla Mux
  • Wire as the dependency injector
  • OpenCensus
  • Viper
  • Sarama

• The application is Dockerized

• The Server is launched in the port :8888

• Metrics and Traces with OpenCensus

• Metrics are exported to Prometheus and can be seen in http://localhost:9090

• Traces are exported to Jaeger and can be seen in http://localhost:16686

How to use the application in your local machine

Launch the application server

make up

Stop the application

make down

Rebuild the application if changes are done to the code

make build

• Only 3 kinds of items can be added to the cart:
  • "book"
  • "dvd"
  • "casette"

To insert new items with a Curl Command

curl -i \
-H "Accept: application/json" \
-H "Content-Type:application/json" \
-X POST --data '{"item_id":"book","quantity":4}' http://localhost:8888/

To get the current cart status

curl -i -X GET http://localhost:8888/

There are unit tests and acceptance, in future iterations also integration should be added. To launch the tests:

make test