Chainlink expands the capabilities of smart contracts by enabling access to real-world data and off-chain computation while maintaining the security and reliability guarantees inherent to blockchain technology.

This repo contains the Chainlink core node and contracts. The core node is the bundled binary available to be run by node operators participating in a decentralized oracle network. All major release versions have pre-built docker images available for download from the Chainlink dockerhub. If you are interested in contributing please see our contribution guidelines. If you are here to report a bug or request a feature, please check currently open Issues. For more information about how to get started with Chainlink, check our official documentation. Resources for Solidity developers can be found in the Chainlink Hardhat Box.

Community

Chainlink has an active and ever growing community. Discord is the primary communication channel used for day to day communication, answering development questions, and aggregating Chainlink related content. Take a look at the community docs for more information regarding Chainlink social accounts, news, and networking.

Build Chainlink

1. Install Go 1.19, and add your GOPATH's bin directory to your PATH
   • Example Path for macOS export PATH=$GOPATH/bin:$PATH & export GOPATH=/Users/$USER/go
2. Install NodeJS & Yarn. See the current version in package.json at the root of this repo under the engines.node key.
   • It might be easier long term to use nvm to switch between node versions for different projects. For example, assuming $NODE_VERSION was set to a valid version of NodeJS, you could run: nvm install $NODE_VERSION && nvm use $NODE_VERSION
3. Install Postgres (>= 11.x).
   • You should configure Postgres to use SSL connection (or for testing you can set ?sslmode=disable in your Postgres query string).
4. Ensure you have Python 3 installed (this is required by solc-select which is needed to compile solidity contracts)
5. Download Chainlink: git clone https://github.com/smartcontractkit/chainlink && cd chainlink
6. Build and install Chainlink: make install
   • If you got any errors regarding locked yarn package, try running yarn install before this step
   • If yarn install throws a network connection error, try increasing the network timeout by running yarn install --network-timeout 150000 before this step
7. Run the node: chainlink help

For the latest information on setting up a development environment, see the Development Setup Guide.

Apple Silicon - ARM64

Native builds on the Apple Silicon should work out of the box, but the Docker image requires more consideration.

Chainlink Docker image currently has an indirect dependency on WebAssemby because of our terra-money/core (CosmWasm) dependency via smartcontractkit/chainlink-terra. This dependency requires a native libwasmvm library, which needs to be sourced depending on the underlying system architecture.

An ARM64 supported Docker image will be built by default on ARM64 systems (Apple Silicon), but there is also an option to add an extra LIBWASMVM_ARCH build argument and choose between aarch64 or x86_64:

# LIBWASMVM_ARCH (libwasmvm.so) architecture choice, defaults to output of `uname -m` (arch) if unset
$ docker build . -t chainlink-develop:latest -f ./core/chainlink.Dockerfile --build-arg LIBWASMVM_ARCH=aarch64

Ethereum Execution Client Requirements

In order to run the Chainlink node you must have access to a running Ethereum node with an open websocket connection. Any Ethereum based network will work once you've configured the chain ID. Ethereum node versions currently tested and supported:

[Officially supported]

• Parity/Openethereum (NOTE: Parity is deprecated and support for this client may be removed in future)
• Geth

[Supported but broken] These clients are supported by Chainlink, but have bugs that prevent Chainlink from working reliably on these execution clients.

• Nethermind Blocking issues:
  • NethermindEth/nethermind#4384
• Besu Blocking issues:
  • hyperledger/besu#4212
  • hyperledger/besu#4192
  • hyperledger/besu#4114
• Erigon Blocking issues:
  • erigontech/erigon#4946
  • erigontech/erigon#4030 (comment)

We cannot recommend specific version numbers for ethereum nodes since the software is being continually updated, but you should usually try to run the latest version available.

Running a local Chainlink node

NOTE: By default, chainlink will run in TLS mode. For local development you can disable this by setting the following env vars:

CHAINLINK_DEV=true
CHAINLINK_TLS_PORT=0
SECURE_COOKIES=false

Alternatively, you can generate self signed certificates using tools/bin/self-signed-certs or manually.

To start your Chainlink node, simply run:

chainlink node start

By default this will start on port 6688. You should be able to access the UI at http://localhost:6688/.

Chainlink provides a remote CLI client as well as a UI. Once your node has started, you can open a new terminal window to use the CLI. You will need to log in to authorize the client first:

chainlink admin login

(You can also set ADMIN_CREDENTIALS_FILE=/path/to/credentials/file in future if you like, to avoid having to login again).

Now you can view your current jobs with:

chainlink jobs list

To find out more about the Chainlink CLI, you can always run chainlink help.

Check out the doc pages on Jobs to learn more about how to create Jobs.

Configuration

Node configuration is managed by a combination of environment variables and direct setting via API/UI/CLI.

Check the official documentation for more information on how to configure your node.

External Adapters

External adapters are what make Chainlink easily extensible, providing simple integration of custom computations and specialized APIs. A Chainlink node communicates with external adapters via a simple REST API.

For more information on creating and using external adapters, please see our external adapters page.

Development

Running tests

1. Install Yarn

2. Install gencodec and jq to be able to run go generate ./... and make abigen

3. Install mockery

make mockery

Using the make command will install the correct version.

4. Build contracts:

yarn
yarn setup:contracts

4. Generate and compile static assets:

go generate ./...

5. Prepare your development environment:

export DATABASE_URL=postgresql://127.0.0.1:5432/chainlink_test?sslmode=disable

Note: Other environment variables should not be set for all tests to pass

6. Drop/Create test database and run migrations:

go run ./core/main.go local db preparetest

If you do end up modifying the migrations for the database, you will need to rerun

7. Run tests:

go test ./...

Notes

• The parallel flag can be used to limit CPU usage, for running tests in the background (-parallel=4) - the default is GOMAXPROCS
• The p flag can be used to limit the number of packages tested concurrently, if they are interferring with one another (-p=1)
• The -short flag skips tests which depend on the database, for quickly spot checking simpler tests in around one minute

Race Detector

As of Go 1.1, the runtime includes a data race detector, enabled with the -race flag. This is used in CI via the tools/bin/go_core_race_tests script. If the action detects a race, the artifact on the summary page will include race.* files with detailed stack traces.

It will not issue false positives, so take its warnings seriously.

For local, targeted race detection, you can run:

GORACE="log_path=$PWD/race" go test -race ./core/path/to/pkg -count 10
GORACE="log_path=$PWD/race" go test -race ./core/path/to/pkg -count 100 -run TestFooBar/sub_test 

https://go.dev/doc/articles/race_detector

Fuzz tests

As of Go 1.18, fuzz tests func FuzzXXX(*testing.F) are included as part of the normal test suite, so existing cases are executed with go test.

Additionally, you can run active fuzzing to search for new cases:

go test ./pkg/path -run=XXX -fuzz=FuzzTestName

https://go.dev/doc/fuzz/

Solidity

Inside the contracts/ directory:

1. Install dependencies:

yarn

2. Run tests:

yarn test

Code Generation

Go generate is used to generate mocks in this project. Mocks are generated with mockery and live in core/internal/mocks.

Nix Flake

A flake is provided for use with the Nix package manager. It defines a declarative, reproducible development environment.

To use it:

1. Nix has to be installed with flake support.
2. Run nix develop. You will be put in shell containing all the dependencies. Alternatively, a direnv integration exists to automatically change the environment when cd-ing into the folder.
3. Create a local postgres database:

cd $PGDATA/
initdb
pg_ctl -l $PGDATA/postgres.log -o "--unix_socket_directories='$PWD'" start
createdb chainlink_test -h localhost
createuser --superuser --no-password chainlink -h localhost

4. Start postgres, pg_ctl -l $PGDATA/postgres.log -o "--unix_socket_directories='$PWD'" start

Now you can run tests or compile code as usual.

Tips

For more tips on how to build and test Chainlink, see our development tips page.

Contributing

Chainlink's source code is licensed under the MIT License, and contributions are welcome.

Please check out our contributing guidelines for more details.

Thank you!

License

MIT