steffqing/smart-contract-event-listener

A smart contract event listener implemented in Node.js, using Web3.js, and deployed on AWS using AWS CDK.

smart-contract-event-listener

Smart contract event listener for Ethereum and other EVM-compatible blockchain networks. This sample repository listens to the Transfer and Approval events of Ethereum's USDT contract.

The smart contract listener is built with:

• Node.js
• TypeScript
• Web3.js

Updating Environment Variables

Refer to the .env.example file.

ETH_WSS_ENDPOINT=wss://eth-mainnet.g.alchemy.com/v2/<YOUR_API_KEY>
ETH_SMART_CONTRACT_ADDRESS=0xdac17f958d2ee523a2206206994597c13d831ec7

For the ETH_WSS_ENDPOINT, you can an endpoint from popular providers such as Alchemy and Infura.

For the ETH_SMART_CONTRACT_ADDRESS, it's referencing the Ethereum USDT contract. If you want to update the contract address, make sure that you also update the src/abi.json to reflect the updated contract address.

Local Development

For local development, you can refer to the following set of commands for starting the smart contract event listener.

1. TypeScript:
   • npm run start:dev
2. JavaScript:
   • npm run build
   • npm run start
3. Docker:
   • npm run build
   • docker build -t smart-contract-event-listener:latest .
   • docker run -d --env-file .env --name smart-contract-event-listener smart-contract-event-listener:latest
   • docker logs smart-contract-event-listener
   • docker stop smart-contract-event-listener

AWS CDK

This project uses AWS CDK as the IaC (Infrastructure as Code) tool for deploying and managing AWS resources.

AWS CDK deploys the following resources:

• VPC
• ECS Cluster
• ECS Fargate Service
• ECS Fargate Task Definition

Deploying with AWS CDK

To deploy the AWS resources, first, you need to have the permissions needed to deploy to your AWS account. You can refer to this [guide](AWS CLI documentation).

Then to deploy, run the following:

• npm run build
• cdk deploy

Useful commands

• npm run build compile typescript to js
• npm run watch watch for changes and compile
• npm run test perform the jest unit tests
• cdk deploy deploy this stack to your default AWS account/region
• cdk diff compare deployed stack with current state
• cdk synth emits the synthesized CloudFormation template