chainlink-mix

This is a repo to work with and use Chainlink smart contracts in a python environment. If you're brand new to Chainlink, check out the beginner walkthroughs in remix to learn the basics.

You can also check out the more advanced Chainlink tutorials there as well.

Prerequisites

Please install or have installed the following:

• nodejs and npm
• python

Installation

1. Install Brownie, if you haven't already. Here is a simple way to install brownie.

pip install eth-brownie

2. Install ganache-cli

npm install -g ganache-cli

3. Download the mix and install dependancies.

brownie bake chainlink-mix
cd chainlink-mix
pip install -r requirements.txt

This will open up a new Chainlink project. Or, you can clone from source:

git clone https://github.com/PatrickAlphaC/chainlink-mix
cd chainlink-mix 

If you want to be able to deploy to testnets, do the following.

1. Set your WEB3_INFURA_PROJECT_ID, and PRIVATE_KEY environment variables.

You can get a WEB3_INFURA_PROJECT_ID by getting a free trial of Infura. At the moment, it does need to be infura with brownie. You can find your PRIVATE_KEY from your ethereum wallet like metamask.

You'll also need testnet rinkeby ETH and LINK. You can get LINK and ETH into your wallet by using the rinkeby faucets located here. If you're new to this, watch this video.

You can add your environment variables to the .env file:

export WEB3_INFURA_PROJECT_ID=<PROJECT_ID>
export PRIVATE_KEY=<PRIVATE_KEY>

AND THEN RUN source .env TO ACTIVATE THE ENV VARIABLES (You'll need to do this everytime you open a new terminal, or learn how to set them easier)

Otherwise, you can build, test, and deploy on your local environment.

Chainlink Price Feeds

This mix provides a simple template for working with Chainlink Smart Contracts. The easiest way to start is to fork the mainnet chain to a local ganache chain. This will allow you to deploy local smart contracts to interact with the Chainlink Price Feeds.

Running Scripts

This will deploy a smart contract to kovan and then read you the latest price via Chainlink Price Feeds.

brownie run scripts/price_feed_scripts/deploy_price_consumer_v3.py --network kovan
brownie run scripts/price_feed_scripts/read_price_feed.py --network kovan

Otherwise, you can fork mainnet and use that in a local ganache development environment.

brownie console --network mainnet-fork
>>> price_feeds = PriceFeed.deploy('0x5f4eC3Df9cbd43714FE2740f5E3616155c5b8419', {'from': accounts[0]})
.
.
>>> latest_price = price_feeds.getLatestPrice()
>>> latest_price
59169208540

You can also use ENS to get prices. See the ens price feed script for more information.

Chainlink VRF

This will deploy a smart contract to kovan and get a Random number via Chainlink VRF.

brownie run scripts/vrf_scripts/deploy_vrf.py --network kovan
brownie run scripts/vrf_scripts/fund_vrf.py --network kovan
brownie run scripts/vrf_scripts/request_randomness.py --network kovan
brownie run scripts/vrf_scripts/read_random_number.py --network kovan

Chainlink API Call

This will deploy a smart contract to kovan and then make an API call via Chainlink API Call.

brownie run scripts/chainlink_api_scripts/deploy_api_consumer.py --network kovan
brownie run scripts/chainlink_api_scripts/fund_chainlink_api.py --network kovan
brownie run scripts/chainlink_api_scripts/request_api.py --network kovan
brownie run scripts/chainlink_api_scripts/read_data.py --network kovan

Testing

brownie test

For more information on effective testing with Chainlink, check out Testing Smart Contracts

Tests are really robust here! They work for local development and testnets. There are a few key differences between the testnets and the local networks. We utilize mocks so we can work with fake oracles on our testnets.

There is a test_unnecessary folder, which is a good exersize for learning some of the nitty-gritty of smart contract development. It's overkill, so pytest will skip them intentionally. It also has a test_samples folder, which shows an example Chainlink API call transaction receipt.

To test development / local

brownie test

To test mainnet-fork

This will test the same way as local testing, but you will need a connection to a mainnet blockchain (like with the infura environment variable.)

brownie test --network mainnet-fork

To test a testnet

Kovan and Rinkeby are currently supported

brownie test --network kovan

Adding additional Chains

If the blockchain is EVM Compatible, adding new chains can be accomplished by something like:

brownie networks add Ethereum binance-smart-chain host=https://bsc-dataseed1.binance.org chainid=56

or, for a fork:

brownie networks add development binance-fork cmd=ganache-cli host=http://127.0.0.1 fork=https://bsc-dataseed1.binance.org accounts=10 mnemonic=brownie port=8545

Linting

pip install black 
pip install autoflake
autoflake --in-place --remove-unused-variables -r .
black .

Resources

To get started with Brownie:

• Chainlink Documentation
• Check out the Chainlink documentation to get started from any level of smart contract engineering.
• Check out the other Brownie mixes that can be used as a starting point for your own contracts. They also provide example code to help you get started.
• "Getting Started with Brownie" is a good tutorial to help you familiarize yourself with Brownie.
• For more in-depth information, read the Brownie documentation.

Any questions? Join our Discord

License

This project is licensed under the MIT license.