Ethereum monitor

Quick start guide

Clone the repo

git clone git@github.com:tbozhikov/ethermon.git

Open the repo folder and install dependencies

npm install

Start the project using one of the npm scripts

npm run start-all

The above steps will start:

An API Server node, that serves a REST API used to manage the dynamic config
A worker node that monitors all Ethereum transactions, filters them and stores them into DB according to the dynamic config/filters

Upon the first run, the solution detects if there isn't a DB and creates one (sqlite), with the needed tables inside. It will also have an empty dynamic config stored in the DB.
Create a filter Use the POST /api/configuration endpoint and pass the filters as JSON args, like so:

curl --location --request POST 'localhost:3000/api/configuration' \
--header 'Content-Type: application/json' \
--data-raw '{
    "transactionFilters": [
        {
            "field": "to",
            "value": "0xc18360217d8f7ab5e7c516566761ea12ce7f9d72",
            "criteria": "equals",
            "matchCase": false
        },
        {
            "field": "to",
            "value": "0x7875c0Dd92be2d313c597136ABF0148682D39A53",
            "criteria": "equals",
            "matchCase": true
        },
        {
            "field": "gas",
            "value": "850000",
            "criteria": "above"
        }
    ]
}'

Observe the console output or logs of the worker - it should hot-reload the configuration and begin storing transactions satisfied by these filters.
Observe the transactions being persisted in DB either using SQL queries/sqllite viewer or using this helper endpoint available in the API Server:

curl --location --request GET 'localhost:3000/api/transactions'

Prerequisites

NodeJS v12.16.1

Features

Monitor all transactions in the Ethereum blockchain
Filter the transactions by managing filters through an API
Store the filters in a DB
Hot-reload of the filters upon change
Store filtered transactions in a DB, storing the id of the configuration that triggered it
Logging solution with file and console outputs

Filters

The supported filter properties are as follows:

property	type	description
field	string	the field, can be any of the Ethereum transaction fields
value	string/number	the field value to match
criteria	string	currently supported are "equals", "above" (for numeric values only), "below" (for numeric values only)
matchCase	boolean	true or false, applies for string values. Performs case insensitive match if false

When multiple filters are provided, logical OR is applied, so if any filter applies successfully, the transaction gets stored.

Application configuration

For both worker and API Server nodes app configs can be tweaked in:

For the worker: ./worker/transaction-monitor.js
For the API Server: ./api/api-staging.json

Improvement areas

Use MoM solution (RabbitMQ, Kafka etc.) for change detection of configuration (instead of current scheduleChangeDetection mechanism using timer)
Run API and Worker nodes in containers
Bundle the nodes so that they are better suitable for deployment on environments
Introduce better/richer filters
Tests