Chainlink Smart Contracts

[!IMPORTANT] Since v1.5.0 of the Chainlink contracts package, some dependencies are no longer vendored and require the use of remappings. See the setup instructions for use in Solidity projects.

Since v1.4.0 of the Chainlink contracts, the contracts have been moved to their own repository: chainlink-evm. Prior to that, the contracts were part of the main Chainlink repository

Table of Contents

• NPM Quick Install
• Setup & Installation
  • Foundry & Forge
  • Hardhat 2
  • Hardhat 3
  • Remix
• Package Directory Structure
  • Usage
• Local Development
• Contributing
  • Changesets

NPM Quick Install

[!NOTE]
For use in Solidity project(s), see the setup instructions below.

# pnpm
$ pnpm add @chainlink/contracts

# npm
$ npm install @chainlink/contracts --save

Setup & Installation

This package relies on Solidity remappings to resolve import paths within your Solidity project(s). Each tool may handle remappings in a different manner.

In the sections below, you will find detailed instructions on this process for supported tools.

Step 1: Install the package

For use in your Foundry project, it is recommended to utilize npm or pnpm as your package manager for the use of this package instead of forge install.

# pnpm
$ pnpm add @chainlink/contracts

# npm
$ npm install @chainlink/contracts --save

If you wish to utilize forge install, please see the Foundry starter kit for detailed information.

Step 2: Set up remappings

Set up your project's remappings. See the Foundry documentation for more information.

Foundry consumes a remappings.txt file from the project root. Create or update your project's remappings.txt with the following, to ensure that it loads the correct version of the dependencies you just installed into your node_modules:

@chainlink/=node_modules/@chainlink
@openzeppelin/[email protected]=node_modules/@openzeppelin/contracts-4.7.3
@openzeppelin/[email protected]=node_modules/@openzeppelin/contracts-4.8.3
@openzeppelin/[email protected]=node_modules/@openzeppelin/contracts-4.9.6
@openzeppelin/[email protected]=node_modules/@openzeppelin/contracts-5.0.2
@openzeppelin/[email protected]=node_modules/@openzeppelin/contracts-5.1.0
@openzeppelin/contracts-upgradeable/=node_modules/@openzeppelin/contracts-upgradeable/
@arbitrum/=node_modules/@arbitrum/
@eth-optimism/=node_modules/@eth-optimism/
@scroll-tech/=node_modules/@scroll-tech/
@zksync/=node_modules/@zksync/

Run forge compile to test that everything compiles correctly.

Troubleshooting unresolved imports

If your compilation reports unresolved imports from dependencies, add the corresponding additional remappings to remappings.txt (the format is <prefix>=<resolved-path>/).

See the Foundry starter kit for working examples.

Step 1: Install the package

# pnpm
$ pnpm add @chainlink/contracts

# npm
$ npm install @chainlink/contracts --save

Step 2: Set up remappings

Hardhat 2 does not handle remappings natively as seen in Foundry/Hardhat 3. To remap import paths, you may use a preprocessor that handles this at compile time. Refer to the remapping section of the Hardhat 2 starter kit for more information.

See the Hardhat 2 starter kit for working examples.

Step 1: Install the package

# pnpm
$ pnpm add @chainlink/contracts

# npm
$ npm install @chainlink/contracts --save

Hardhat 3 supports remappings.txt files in your project, as well as in Git submodules and npm dependencies. Each remappings.txt file applies to the directory where it's located and all its subdirectories, similar to how .gitignore works.

Similar to Foundry, Hardhat 3 will utilize the remappings.txt file located within the root directory of this Chainlink contracts package.

See the Hardhat 3 starter kit for working examples.

Remix works out of the box and requires no additional setup or installation. The imported dependencies will be automatically installed.

Package Directory Structure

[!IMPORTANT] Since v1.5.0 of the Chainlink contracts, ABI files have been reorganized into subdirectories. Additionally, ABI files now follow a slightly updated naming scheme.

@chainlink/contracts
├── src # Solidity contracts
│   └── v0.8
└── abi # ABI JSON output
    └── v0.8

Usage

The Solidity files themselves can be imported via the src directory of @chainlink/contracts:

import {IVerifier} from '@chainlink/contracts/src/v0.8/llo-feeds/v0.5.0/interfaces/IVerifier.sol';

The ABI files themselves can be imported via the abi directory of @chainlink/contracts:

@chainlink/contracts/abi/v0.8/VRF/VRFCoordinatorV2_5.abi.json

Local Development

Note: Contracts in dev/ directories or with a typeAndVersion ending in -dev are under active development and are likely unaudited. Please refrain from using these in production applications.

# Clone Chainlink repository
$ git clone https://github.com/smartcontractkit/chainlink.git
$ cd contracts/
$ pnpm

Each Chainlink project has its own directory under src/ which can be targeted using Foundry profiles. To test a specific project, run:

# Replace <project> with the product you want to test
export FOUNDRY_PROFILE=<project>
forge test

To test the llo-feeds (data streams) project:

export FOUNDRY_PROFILE=llo-feeds
forge test

Contributing

Please adhere to the Solidity Style Guide.

Contributions are welcome! Please refer to Chainlink's contributing guidelines for detailed contribution information.

Thank you!

Changesets

We use changesets to manage versioning the contracts.

Every PR that modifies any configuration or code should most likely be accompanied by a changeset file.

To install changesets:

1. Install pnpm if it is not already installed - docs.
2. Run pnpm install.

Either after or before you create a commit, run the pnpm changeset command in the contracts directory to create an accompanying changeset entry which will reflect on the CHANGELOG for the next release.

The format is based on Keep a Changelog,

and this project adheres to Semantic Versioning.