Payment system

Introduction

This application uses a classic MVC architecture along with some popular Golang libraries (GORM, Ginkgo, Gomega, gorilla/mux) and PostgreSQL as a DB for an implementation of a simple payment system.

Its directory strcuture is created accordingly to the MVC pattern: You can find:

• Models in models package
• Views in views package
• Controllers in controllers package

The application starts an HTTP server, which also serves static HTML that presents the merchants (and their transactions).

You can access it by opening your browser and following thi next link for a local setup:

• http://localhost:8080/views/merchant

Configuration

Most of the configurations for this application can be made using environment variables. Check out the Go structs defined in the config package and pay attention to the envconfig tags to find out which are the environment variables that can be used.

Security (dummy)

The following API endpoints are secured by JWT tokens:

• POST /transaction (Create a transaction)
• PUT /merchant (Update a merchant)
• DELETE /merchant (Delete a merchant)

The security mechanism implemented is really simple. Your JWT token's sub claim needs to match the merchant's email. Since no passwords are stored in the DB and no login endpoints in exposed, you can craft the tokens yourself by using the JWT debugger and secretKey as the signature's secret.

CSV import

You can set the following environment variables to a .csv file path :

• APP_MERCHANTS_IMPORT_PATH for merchants
• APP_ADMINS_IMPORT_PATH for admins

Having set those, the application will load these users on startup by reading the specified .svc file.

For the file format, check out assets/csv.

You can comment/uncomment lines 11 & 12 in docker-compose.yml to control the behavior in a Dockerized environment.

Running locally

Docker compose

The simplest way to run this project is using Docker Compose.

If you have docker compose installed, you can run the following commands in the project root to start the application in a container:

docker-compose build
docker-compose up

Tested using

• docker-compose v2.13.0
• Docker Desktop 4.15.0

Local startup

If you want to start this project locally (not in a container environment), you will need to make sure that you have a postgresql instance running with the proper schema migrations executed against it.

You can execute the migrations using sqlmigrate by running the following command in project root:

migrate -path /sql -database  "postgres://YOUR_DB_USER:YOUR_DB_PASS@YOUR_DB_HOST:YOUR_DB_PORT/YOUR_DB_NAME?sslmode=disable" up

Note: this works for Postgres instances which are configured to run in disabled SSL mode

Then, once you've made sure that your environment is correctly configured (see Configuration above) run the application by running the following command in project root:

go run cmd/main.go

Tested using

• go 1.19.4
• migrate 4.14.0
• postgres v15.1

Example API requests

Since data modification is only possible by making HTTP Requests (not enough spare time to implement a React frontend :/ ) you can find a Postman collection with sample requests in assets/http.