Watchtower

Watchtower is a microservice and REST API to monitor transactions, balances, and derived addresses for BIP32 ExtendedPublicKeys (xpubs). This enables view-only functionality in HD wallets such as KeepKey without needing the actual device connected (after initizliation with Watchtower) and without storing any private keys.

Supported coins

BTC, BCH, LTC, DASH, DOGE, DGB, ETH, ERC-20 tokens

API

API.md

Development Environment

Requirements

Docker and Docker-Compose

Quick Start

1. Make sure you have docker and docker-compose installed on your system
2. Make a local copy of the sample config file: cp config/sample.local.json config/local.json
3. Create a unique apiKey or else you will be 4XX'd by CoinQuery:
   1. Edit .env and change the ENV var to local-{name}
   2. Make a copy or symlink of watchtower/settings/local.py and rename to local-{name}.py
   3. Add watchtower/settings/local-{name}.py to .git/info/exclude or your global .gitignore file
4. Run docker-compose up --build to quickly bring up watchtower, postgres, and redis preconfigured and bound to their default ports

Docker Containers

• Scheduler - kicks off tasks using Celery
• Workers - includes block ingester
• Postgres - transaction and balance history indexed by xpub
• Redis - Celery message broker. Stores addresses to monitor in the mempool (generated receive addresses for currently connected clients)
• RabbitMQ - AMQP message broker. The block ingester service publishes messages to RabbitMQ when it detects a new transaction that affects an xpub in the watchtower DB.

Test

Manually run watchtower tests:

docker-compose up --build

(and in a separate terminal)
docker exec -it watchtower bash
python manage.py test

Utils

Rabbit Logger is a script that connects to the local RabbitMQ server and prints each message published to exchange <exchange>. For watchtower, this is typically exchange.watchtower.txs or exchange.watchtower.blocks

`python3 utils/rabbit-logger.py <exchange>`

Misc dev notes

• python manage.py migrate - initialize database tables
• python manage.py createsuperuser - create admin user for debugging
• fab serve - start local webserver
• fab celery_scheduler - start periodic job scheduler
• fab celery_workers - start worker daemons to process jobs (optional)
• docker-compose down -v - clear persistent postgres data
• developer workflow: hot reloading in iPython

Dev repl workflow example

docker exec -ti watchtower python manage.py shell

enable hot reloading

%load_ext autoreload
%autoreload 2

at this point you can import modules and they will hot reload on changes e.g.

init bnb

from common.services import binance_client
binance_client.get_latest_block_height()

init fio

from common.services import fio
fio.get_latest_block_height()

get block at height

fio.get_block_at_height(29990325)

History api get transactions at height

fio.get_transactions_at_height("iyz3zveyg23i")

RabbitMQ Admin interface

• http://localhost:15672
• default rabbit user/pass

Design Considerations

The primary goals in designing Watchtower's architecture were the following:

1. Infrastructure costs will scale:
   • independent of the number of users/xpubs/transactions being tracked, and
   • proportional to the number of supported blockchains
2. Easily add support for new assets

Known Limitations

• Watchtower does not publish internal Ethereum transactions to RabbitMQ (i.e. smart contract calls). Instead WT users should query (poll) the ethereum transaction history endpoint to get a list of internal transactions for an account.

troubleshooting

if rabbit is refusing connections. And docker-compose failing to startup locally. Increase your CPU