blockchain-data-engineering-toolkit/token-scanner-api

🛠🪙 token scanner api and cli

👉 this project implements a cli tool that indexes transfer events for a particular token, and is deployed to a restful api for fast balance and ownership statistics retrieval. it utilizes JSON-RPC methods eth_blockNumber and eth_getLogs.

🛠 system design for this project:

📚 more details can be found in my mirror post, quant #3: building a scalable event scanner for ethereum.

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setting up

installing dependencies

because of some of the dependencies in this code, we will be developing on a python3.9 environment (install here if you don’t have that version on disk):

virtualenv -p /usr/local/bin/python3.9 venv
source venv/bin/activate
pip3 install -r requirements.txt

adding environment variables

create a .env file and add an RPC_PROVIDER_URL to connect to ethereum mainnet nodes (for example, from this list):

cp .env.example .env
vim .env

installing the package

make install

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running

indexer -h

🪙 Token indexer and API.

optional arguments:
  -h, --help  show this help message and exit
  -e          Retrieve historical transfer events data on Ethereum. Example: indexer -e
  -p PROCESS  Process historical transfer events data. Example: indexer -p <json data file>
  -d DB       Populate db with processed event data. Example: indexer -d <json data file>
  -a          Run the event scanner api locally. Example: indexer -a
  -c          Deploy event scanner to Vercel. Example: indexer -c
  -b BALANCE  Fetch token balance for a given wallet. Example: indexer -b <wallet address>
  -t TOP      Fetch top token holders. Example: indexer -t <number of holders>
  -g CHANGE   Fetch weekly balance change for a given wallet. Example: indexer -g <wallet address>

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development

deploying in production

we use vercel to deploy this app:

vercel login
vercel .