YAXIS DISCORD WEBHOOK

Objective

Create a Discord webhook to poll Etherscan ERC-20 internal transactions associated with MetaVault v2 contract and display buybacks executed by its active strategies.

Installation instructions

Runs on node.js and a Postgres SQL database. Tested with node.js v16.1.0 and Postgres SQL v13.2.

node.js code is really 2 files:

lib/app.js containing most of the code, and
lib/db.js encapsulating the DB initialization routines and exposing a query() method to run all SQL queries. It's worth noticing that the db.js::init() function creates all needed tables in the PSQL database that you chose via the DATABASE_URL environment variable (see below).

PSQL database uses 2 tables:

transactions saving the data relative to all past buyback transactions
tokenHistoricalPrices saving YAXIS v2 token price at the time of each transactions

Pre-requisites

Install latest version of node.js and PSQL
Create a PSQL database of your choosing and set the URI accordingly (e.g. yaxis_discord)
(Optional) Run the SQL install script to load historical token prices. It's optional to run it, if no data exists the script will use the current token price (same behavior as Etherscan but not accurate for past transactions)
Edit package.json file and update the environment variables in script.local (see environment variables below)

Environment variables

Several environment variables were created to override the content of config.json

WEBHOOK_ID: the ID of Discord's webhook to post messages to
WEBHOOK_TOKEN: associated Discord's webhook token
YAXIS_EMOJI_NAME & YAXIS_EMOJI_ID: Discord emoji code used to display the Yaxis emjoi. As it's a custom emoji, you'll have to install it on your server and use the following command to get the ID \:[your token name]
ETHERSCAN_API_KEY: Etherscan API (should work without any API key as a default rate limit of 1 txn per 5s will be applied)

config.json file

discord.webhook > same as WEBHOOK_ID & WEBHOOK_TOKEN environment variables
discord.emoji > same YAXIS_EMOJI_NAME & YAXIS_EMOJI_ID environment variables
etherscan.api_key > same as ETHERSCAN_API_KEY environment variable
yaxis > various constants relative to the YAXIS project. yaxis.metavault.startblock is the startblock used in case none can be found in the DB
refresh > default sleep time before fetch new transactions from Etherscan API (5min by default)

To launch the script

Use npm run local. npm start is used by Heroku or equivalent solutions.