triplet · travel expense diary
Period
triplet records foreign‑currency cash and card spending together and automatically converts it to won at the current exchange rate. We built it at the Shinhan Bank hackathon during SSAFY. It was my first project with JPA and my first deployment. I handled half of the server and CI/CD setup.
Selected for the Shinhan Bank hackathon from 8 applicants per place
- Trip creation with budget and cash on hand
- Currency exchange requests
- Calendar‑style expense diary
- Image upload
Working with a dummy bank API
- Problem
- Security and technical issues kept a real bank API out of reach, so the hackathon ran on a dummy‑data API. We had to work out the transaction logic and exchange rate information ourselves.
- Solution
- Built additional APIs and dummy data for spending, exchange‑rate and other cases. We used that data to reproduce each user scenario while building features.
Running out of instance resources
- Problem
- To run at no cost, we put all containers on one AWS Free Tier instance. Usage kept climbing until the instance shut down.
- Solution
- I considered upgrading to a paid size but configured memory swap on the 1 GB RAM instance instead. As it was my first deployment, finding the cause took a long time.
Architecture
