Getting Started with Web3 and Python

This repository is an accompaniment to the Doppler and Web3 published at ${URL} and all of the code used in the article (and more) is contained in web3-app.py.

You can view the available commands once setup by running:

python web3-app.py --help

Requirements

• Alchemy account
• Python 3
• Geth CLI (installation docs)

Setup

The following instructions use Homebrew for macOS but can easily be adapted for Linux and Windows.

Install Python3 and Ethereum:

brew install python
brew tap ethereum/ethereum
brew install ethereum

The Geth CLI should now be on your $PATH:

geth version

In a background terminal, create a connection to the Goerli test Ethereum network:

# --syncmode light` downloads block headers without transactions to save disk and memory space
geth --syncmode light --datadir ~/.goerli --goerli

Clone the repository:

git clone https://github.com/DopplerUniversity/python-web3
cd python-web3

Then create a virtual environment and install the dependencies:

python3 -m venv .venv
source .venv/bin/activate
pip install --upgrade pip setuptools
pip install -r requirements.txt

Test everything is setup by running:

python web3-app.py --help

Doppler

Next, we'll install the Doppler CLI and create a Doppler project for storing the passphrase for your test Ethereum account.

Install the CLI:

# See https://docs.doppler.com/docs/enclave-installation for other operating systems and environments, e.g. Docker
brew install dopplerhq/cli/doppler

Authenticate your machine:

doppler login

Then create the python-web3 Doppler project:

doppler projects create python-web3
doppler setup --project python-web3 --config dev

Test Account

The creation of your test account (a locally encrypted file in the ~/.goerli directory) is protected using a passphrase which must be provided when performing actions such as making a transaction.

Doppler will be used for storing the passphrase so it can securely injected as an environment variable using the Doppler CLI.

Without a SecretOps platform such as Doppler, storing the passphrase in an unencrypted local file risks that file being accidentally committed to GitHub with disastrous consequences.

Create a new ETH_PASSPRASE secret in Doppler to store your passphrase:

doppler secrets set ETH_PASSPHRASE

Then use the Doppler to inject your passphrase into the Geth CLI command for creating your test account:

doppler run --command='geth account new --datadir ~/.goerli --password <(echo "$ETH_PASSPHRASE")'

Now verify your account has been created by running:

python web3-app.py accounts

Add Funds

Now add test funds to your new account using the Goerli Faucet where you can request 0.05 Goerli ETH per day.

The Goerli Faucet is an Ethereum faucet built for developers to test and troubleshoot their decentralized application or protocol before going live on Ethereum mainnet.

Once you've requested your 0.05 Goerli ETH, you can verify it's in your account by running:

python web3-app.py balance

Send Transaction

You'll need an address for sending a transaction which you can get from the Goerli accounts page.

Now use the Doppler CLI to dynamically inject the ETH_PASSPHRASE value as an environment variable into the Python process:

# Replace {ADDRESS} with the public address of the wallet you would like to send funds to e.g. 0xe0a2bd4258d2768837baa26a28fe71dc079f84c7
doppler run -- python web3-app.py send {ADDRESS} 0.01

You can then use the returned hash to view the transaction details:

python web3-app.py get-txn {TRANSACTION_HASH}

Summary

Now you know how to get started building a Python Web3 application using the Doppler SecretOps platform for secure management of your passphrase.