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Contribute to Prysm's codebase

There are a number of ways to help out the project for people of all skillsets and experience levels. If you are unsure where you may be best suited, stop by either our Discord and a member of the team or community will be happy to answer questions and offer some direction.

Getting Started

Once you are a bit more familiar with the concepts behind Ethereum and are ready to write some code, head over and explore Prysm's open issues on Github. We recommend looking for issues tagged with the Good First Issue label if it is your first contribution. If you are still unsure about how to tackle a bug or a feature, our team is always available on Discord. Sign in to your Github account, then navigate to the official Prysm repository. In the upper right hand corner of the page, click the Fork button. This will create a copy of the Prysm repository on your account that can be edited for pull requests.

Setting up your environment

To develop Prysm, you'll need the following:

  • A modern Windows, MacOS X, or Minux operating system
  • Go 1.21 version installed, download and install here
  • The git package installed
  • A code editor such as Visual Studio Code or Jetbrains' Goland IDE or your preferred one

First, create a local clone of Prysm.

git clone && cd prysm

Then link your local repository to your newly created fork.

git remote add myprysmrepo<your_github_user_name>/prysm.git

Finally, ensure Go is installed and working on your machine:

go version

Example output:

go version go1.21.5 darwin/arm64

Building and testing Prysm with Go

The Prysm project is a large monorepo containing all sorts of tools and services that implement the Ethereum protocol. We use Go for everything we do in development, helping everyone have reproducible builds. If you want to build the whole project, you can run the following command:

$ go build -v ./...

This will build the project by downloading dependencies as Go modules.

Running Go tests

All code we check into our repo needs to have sufficient tests to ensure it is maintainable and works as expected.

Many tests rely on the Bazel build system, thus testing with go test may not work.

If you decide to do so and if you get the following error:

Caught SIGILL in blst_cgo_init, consult <blst>/bindings/go/

Please define the following environment variable when running tests:


It is particulary useful when running tests / debug in your IDE without using bazel.

See the next section for instructions on testing with prysm.

Building and testing Prysm with Bazel

The Prysm project is a large monorepo containing all sorts of tools and services that implement the Ethereum consensus protocol. We use the Bazel build system created by Google for everything we do, helping everyone have reproducible builds.

To build the beacon chain, run the following command:

bazel build //cmd/beacon-chain

To build the validator client, run the following command:

bazel build //cmd/validator

Other binaries in our codebase use a similar command to build. If you want to run a particular built binary, you can use the command:

bazel run //cmd/beacon-chain -- --help

Where you can specify any amount of command line arguments you need based on the available flags of the item you're running.

In order to write code for the Prysm codebase comfortably with Bazel, we recommend using either Visual Studio Code with its Bazel plugin, or any Jetbrains IDE with the Bazel plugin (Goland is a great choice, used by most of the Prysmatic Labs team).

You can also find various other types of IDE support for Bazel in the official Bazel documentation here. Once you have your coding environment set-up, you'll be well-equipped to contribute to Ethereum!

Running Bazel tests

All code we check into our repo needs to have sufficient tests to ensure it is maintainable and works as expected. We use bazel to run all of our test suites in Prysm. If there is a particular subfolder you want to test, such as beacon-chain/node, you can run the command:

bazel test //beacon-chain/node:go_default_test

For running a specific test, for example, a test called TestNodeStart_Ok inside of beacon-chain/node, you can use Bazel to filter it out:

bazel test //beacon-chain/node:go_default_test --test_filter TestNodeStart_Ok

To display logs while running the test, you can add the --test_output streamed option, such as:

bazel test //beacon-chain/node:go_default_test --test_output streamed --test_filter TestNodeStart_Ok

To run all tests recursively under a directory, you can use the ... syntax. The following example runs all tests recursively under the validator/client directory:

bazel test //validator/client/...

For the list of all available flags to the bazel test command, you can see the reference documentation here.

You can also run our full, end-to-end test suite with:

bazel test //testing/endtoend:go_default_test

Adding dependencies

If you want to add a new dependency to Prysm, please adhere to the guidelines found in our document.

Contributing to the Ethereum consensus API

The Ethereum consensus API implemented by Prysm is maintained as a separate repository than Prysm. You can read more about how to contribute specifically to the API here.

Making your first contribution

Each time you begin a set of changes, ensure that you are working on a new branch that you have created as opposed to the master of your local repository. By keeping your changes segregated in this branch, merging your changes into the main repository later will be much simpler for the team.

To create a local branch for git to checkout, issue the command:

git checkout -b feature-in-progress-branch

To checkout a branch you have already created:

git checkout feature-in-progress-branch

Preparing your commit

To fetch changes to the Prysm repository since your last session:

git fetch origin

Then synchronize your master branch:

git pull origin master

To stage the changed files that are be committed, issue the command:

git add --all

Once you are ready to make a commit, you can do so with:

git commit  -m “Message to explain what the commit covers”

The –-amend flag can be used as well to include previous commits that have not yet been pushed to an upstream repository.

If there are conflicts between your edits and those made by others since you started work Git will ask you to resolve them. To find out which files have conflicts, run:

git status

Open those files, and you will see lines inserted by Git that identify the conflicts:

<<<<<< HEAD
Other developers’ version of the conflicting code
Your version of the conflicting code
'>>>>> Your Commit

The code from the Prysm repository is inserted between <<< and === while the change you have made is inserted between === and >>>>. Remove everything between <<<< and >>> and replace it with code that resolves the conflict. Repeat the process for all files listed by Git status to have conflicts.

When you are ready, use git push to move your local copy of the changes to your fork of the repository on Github.

git push myrepo feature-in-progress-branch

Opening a pull request

Navigate to your fork of the repository on Github. In the upper left where the current branch is listed, change the branch to your newly created one. Open the files that you have worked on and ensure they include your changes.

Navigate to and click on the New pull request button. In the base box on the left, leave the default selection base: develop the branch that you want your changes to be applied to. In the compare box on the right, select the branch containing the changes you want to apply. You will then be asked to answer a few questions about your pull request. Pull requests should have enough context about what you are working on, how you are solving a problem, and reference all necessary information for your reviewers to help.

After you complete the questionnaire, the pull request will appear in the list of pull requests.

Following up

Core developers may ask questions and request that you make edits. If you set notifications at the top of the page to not watching, you will still be notified by email whenever someone comments on the page of a pull request you have created. If you are asked to modify your pull request, edit your local branch, push up your fixes, then leave a comment to notify the original reviewer that the pull request is ready for further review.