/solana-bank-simulator

Primary LanguageTypeScript

Bank Simulator with Interest

How to Build & Run

  1. You would need to deploy the program on Solana blockchain first. You can use SolPg to get started quickly or clone this and work locally:
  • SOLPg
  • Working Locally
    • Install Anchor, Rust and Solana CLI and Clockwork CLI and clone this repository
    • Run clockwork localnet
    • Then, open a new terminal instance and head over to program/ directory using cd program/ command.
    • Enter anchor build and yarn install in the same directory.
    • Then, enter anchor deploy, you'll get a program Id at the end, copy it and paste it in declare_id macro and in Anchor.toml localnet section
    • Finally, enter anchor test --skip-local-validator to build everything and run tests.

Note that you may have some issues using latest version of Solana CLI. It is recommend that you install Solana CLI version 1.14.18 If you see blockhash keep expiring when you run anchor deploy or when running anchor test, then just stop your clockwork validator and re-start it. That will solve the issue.

  1. To launch the frontend, head over to /app directory and enter: yarn install && yarn dev

Automation

We'll be using Clockwork for running a cron job that updates our balance with interest returns every 10 seconds. In the real world, interest returns are deposited on a periodic basis, the interval however is large, like quarterly or yearly. We'll be depositing every 10 seconds to quickly observe changes and understand better.

Clockwork has a thing called Threads, which trigger certain instruction based on a certain trigger condition. For our case, the trigger condition is a Cronjob every 10 seconds.

One important thing about our dApp is that our interest returns will stop after about 5 minutes, the reason for that is that Clockwork requires some amount of fee to run each automation transaction. In our program, we're defining a very small fee. We can increase it to enable our automation to work for a longer time!

Anchor Program

Let's go through the code and understand how our program works.

  1. Constants
  • 1.1 Interest, Cron Schedule, Automation Fee
  • 1.2 Seeds
  1. Initializing Account
  • 2.1 Defining InitilizeAccount context
  • 2.2 Defining Clockwork Target Instruction and Trigger
  • 2.3 Making a CPI to Clockwork program
  1. Updating Balance
  • 3.1 Depositing Amount
  • 3.2 Withdrawing Amount
  • 3.3 Adding Interest