Payment Service

A flexible and extensible payment service designed to integrate with multiple payment gateways. You can find the design document here and openapi spec here

Features

• Modular architecture for easy integration of new payment gateways
• Configurable retry mechanism with customizable backoff strategies
• Flexible serialization/deserialization support
• Abstracted protocol handling for various communication methods
• Comprehensive error handling and logging

Prerequisites

• Go 1.23
• make
• Docker

Build and Run

1. Install necessary dependencies

make init 

2. Run app and postgres

make docker-compose/up

3. Run database migrations

export PGDATABASE=payment
export DATABASE_URL=postgres://postgres:postgres@localhost:5432/payment
export GOOSE_MIGRATION_DIR=db/migrations
export GOOSE_DRIVER=postgres
export GOOSE_DBSTRING="$DATABASE_URL"

goose up

4. Access the API on http://localhost:8080

To stop API and postgres

make docker-compose/down

Run Tests

make test

Curl commands

1. Create transaction

curl --request POST \
  --url http://localhost:8080/api/v1/transactions \
  --header 'Content-Type: application/json' \
  --data '{
  "amount": 123,
  "type": "withdrawal",
  "currency": "USD",
  "payment_method": "BANK_TRANSFER",
  "description": "payment",
  "customer_id": "cus123",
  "preferred_gateway": "gatewayB",
  "metadata": {
		"orderID": 123
	}
}'

2. Gateway A callback

curl --request POST \
  --url http://localhost:8080/api/v1/gateways/gatewayA/callback \
  --header 'Content-Type: application/json' \
  --data '{
	"ref_id": "TiOIptTKAggASOT5wu3i",
	"status": "success"
}'

3. Gateway B callback

curl --request POST \
  --url http://localhost:8080/api/v1/gateways/gatewayB/callback \
  --header 'Content-Type: application/xml' \
  --data '<?xml version="1.0" encoding="UTF-8"?>
<callback>
  <ref_id>isbKQ4O8LHtIViY61ADa</ref_id>
  <status>success</status>
</callback>'

4. Update status API

Replace with id in the path

curl --request PATCH \
  --url http://localhost:8080/api/v1/transactions/vxOAi2w6ZQB1pilXYitU/status \
  --header 'Content-Type: application/json' \
  --data '{
	"gateway": "gatewayB",
	"status": "success"
}'

Libraries/ Tools Used

1. sqlc
2. goose
3. sony/gobreaker circuit breaker

Further improvements

1. Improve test coverage
2. Take config from environment variables