Watching of contract events simplified

A docker container that simplifies watching, handling (and listening to that handle with a websocket) and live logging blockchain contract events.

Running the docker image

Create a docker-compose.yml

Add contracts on the fly

You can use this API doc to interact with the API:

https://documenter.getpostman.com/view/18943422/UVyxRZqd

version: '3'
services:
  listener:
    image: agencyenterprisestudio/block-watcher
    ports:
      - '3000:3000'
      - '80:80'
    environment:
      - PORT=3000
      - NETWORK_TYPE=evm
    volumes:
      - ./storage:/app/storage

Listen to a single contract

version: '3'
services:
  listener:
    image: agencyenterprisestudio/block-watcher
    ports:
      - '3000:3000'
      - '80:80'
    environment:
      - PORT=3000
      - NETWORK_TYPE=evm
      - WEBHOOK_URL={YOUR-APP-WEBHOOK}
      - CONTRACT_ABI_URL={LINK-TO-ABI}
      - CONTRACT_ADDRESS={YOUR-CONTRACT-ADDRESS}
      - PROVIDER_URL={YOUR-WEB3-PROVIDER-URL}
      - CHECK_INTERVAL={TIME-IN-MS}
      - LAST_PROCESSED_BLOCK={LAST-PROCESSED-BLOCK-NUMBER}
    volumes:
      - ./storage:/app/storage

All options

version: '3'
services:
  listener:
    image: agencyenterprisestudio/block-watcher
    ports:
      - '3000:3000'
      - '80:80'
    environment:
      - PORT=3000
      - NETWORK_TYPE=evm
      - WEBHOOK_URL={YOUR-APP-WEBHOOK}
      - CONTRACT_ABI_URL={LINK-TO-ABI}
      - CONTRACT_ADDRESS={YOUR-CONTRACT-ADDRESS}
      - PROVIDER_URL={YOUR-WEB3-PROVIDER-URL}
      - CHECK_INTERVAL={TIME-IN-MS}
      - LAST_PROCESSED_BLOCK={LAST-PROCESSED-BLOCK-NUMBER}
    volumes:
      - ./storage:/app/storage

Available settings | variables

PORT

The port you'll be using for the socket application.

WEBHOOK_URL

The webhook url you can use to send the events for processing. the data sent to the

NETWORK_TYPE

The container currently supports evm based network types. You can set evm.

CONTRACT_ABI_URL

A public URL where the container can fetch the contract ABI JSON in order to process the events.

CONTRACT_ADDRESS

The address of the contract you want to watch.

PROVIDER_URL

The URL of your network provider.

CHECK_INTERVAL

The time in MS in which the watcher will fetch the contract blocks.

Connecting to the socket

We're using the socket to listen to events once they're fully processed. Let's say you have an event listener for when a purchase is processed, you can use the socket in the interface to watch it.

const socket = io('http://localhost:3000')
socket.on('CONTRACT_EVENT_HANDLED', event => {
  console.log('event', event)
})