Cooler Loans API

Purpose

This repository contains the source code for middleware that will provide time-series data related to Cooler Loans.

Design

This repository deploys two API endpoints:

• generate

  • Generates daily snapshots for Cooler Loans.
    • Each snapshot is based on the previous day's snapshot (where applicable), in combination with the loan events (e.g. repayment) from that day.
    • Loan events are processed in the order that they occur.
  • A Google Cloud Function (with a periodic trigger) determines the previous date for which the snapshot was generated, and generates from that day onwards.
  • The snapshots are stored in Google Firestore

• get

  • Fetches the daily snapshots for the given startDate and beforeDate

Developer

Environment

• Install JDK 11+, which is required for the firestore emulator
  • On Mac:
    • Install OpenJDK: brew install openjdk@11
    • Let the system know where OpenJDK 11 is installed: sudo ln -sfn /opt/homebrew/opt/openjdk@11/libexec/openjdk.jdk /Library/Java/JavaVirtualMachines/openjdk-11.jdk
    • Switch to OpenJDK 11 by default: /usr/libexec/java_home -v 11
• Install the firebase emulator
  • gcloud emulators firestore start
• Copy the .env.sample file to .env and fill out the required variables

Testing

• Run the firestore emulator: yarn firestore:start
• yarn test

Rebuild Snapshots

If the daily snapshots need to be rebuilt (e.g. change in the subgraph or the snapshot structure), simply delete the snapshots collection in the GCP project's Firestore section.

This can alternatively be achieved using the firebase CLI:

firebase firestore:delete --recursive "/snapshots" -P <GCP PROJECT>

OpenAPI

REST API clients can utilise the openapi/openapi.yml file to generate typings. The schema, contained in openapi/snapshot.yaml is regenerated with the yarn codegen command.