Crebito - Hexagonal Architecture in GO

This project is part of the Rinha de Backend - 2024/Q1 challenge, which consists of developing an application that is capable of processing a very large volume of concurrent requests (credits and debits) while maintaining the consistency of a current account balance.

Stack

• GO (1.22 frameworkless, with routing enhancements ⚡️)
• MariaDB
• Nginx
• Docker

API Architecture

The API needs to be in two containers, using a database and accessed through a load balance on port 9999, where it will do a round robin distributing the requests.

Constraints

The total resource limit available for all application services is 550MB RAM and 1.5 CPU unit.

The distribution of resources for this project was as follows:

Service	Memory	CPU unit
API-1	30MB	0.2
API-2	30MB	0.2
Load Balancer	20MB	0.1
Database	210MB	0.7
Total	290MB	1.2

Application Architecture

The application was developed using the hexagonal architecture (Ports and Adapters) where the Use Case layer represents the application logic, and the Service layer the business logic.

Running

To create the database container (rinha-db) so that you can run the application locally:

$ make dev

To run all the containers (application, database and load balancer) with CPU and memory restrictions already applied. And then you can access it via the url http://localhost:9999/

$ make prod

Removes all containers: rinha-api1, rinha-api2, rinha-alb and rinha-db.

$ make clean

Build the Docker image.

$ make build

Endpoints

The application contains the following REST APIs:

Create transaction

Method	Target	Description
POST	/clientes/{id}/transacoes	Creates a credit or debit transaction on the account entered.

Request

Example of body request:

{
  "valor": 1000,
  "tipo" : "c",
  "descricao" : "pix"
}

• The value is a positive integer already containing the cents.
• The tipo must be c for credit and d for debit.
• The description cannot be longer than 10 characters.

Response

200 Sucess:

{
  "limite": 100000,
  "saldo": -3000
}

• Returns the account limit and the updated balance after processing the transaction.

422 Unprocessable Entity:

{
  "code": 422,
  "message": "account: insufficient funds"
}

• If the account does not have enough to process the transaction.

List Extracts

Method	Target	Description
GET	/clientes/{id}/extrato	Lists the last 10 transactions made on an account, as well as its current balance and limit value.

Response

200 Sucess:

{
  "saldo": {
    "total": -3000,
    "data_extrato": "2024-03-10T02:26:14.02115Z",
    "limite": 100000
  },
  "ultimas_transacoes": [
    {
      "valor": 1000,
      "tipo": "c",
      "descricao": "pix",
      "realizada_em": "2024-03-09T23:26:11.669223Z"
    },
    {
      "valor": 2000,
      "tipo": "d",
      "descricao": "pipoca",
      "realizada_em": "2024-03-09T23:25:51.692163Z"
    },
    {
      "valor": 1000,
      "tipo": "d",
      "descricao": "cinema",
      "realizada_em": "2024-03-09T23:25:40.543701Z"
    },
    {
      "valor": 1000,
      "tipo": "d",
      "descricao": "picole",
      "realizada_em": "2024-03-09T23:25:28.527101Z"
    }
  ]
}

404 Not found:

{
  "code": 404,
  "message": "account: not found"
}