tendermint/CONTRIBUTING.md

Contributing

Thank you for your interest in contributing to Tendermint! Before contributing, it may be helpful to understand the goal of the project. The goal of Tendermint is to develop a BFT consensus engine robust enough to support permissionless value-carrying networks. While all contributions are welcome, contributors should bear this goal in mind in deciding if they should target the main Tendermint project or a potential fork. When targeting the main Tendermint project, the following process leads to the best chance of landing changes in master.

All work on the code base should be motivated by a Github Issue. Search is a good place start when looking for places to contribute. If you would like to work on an issue which already exists, please indicate so by leaving a comment.

All new contributions should start with a Github Issue. The issue helps capture the problem you're trying to solve and allows for early feedback. Once the issue is created the process can proceed in different directions depending on how well defined the problem and potential solution are. If the change is simple and well understood, maintainers will indicate their support with a heartfelt emoji.

If the issue would benefit from thorough discussion, maintainers may request that you create a Request For Comment in the Tendermint spec repo. Discussion at the RFC stage will build collective understanding of the dimensions of the problems and help structure conversations around trade-offs.

When the problem is well understood but the solution leads to large structural changes to the code base, these changes should be proposed in the form of an Architectural Decision Record (ADR). The ADR will help build consensus on an overall strategy to ensure the code base maintains coherence in the larger context. If you are not comfortable with writing an ADR, you can open a less-formal issue and the maintainers will help you turn it into an ADR.

How to pick a number for the ADR?

Find the largest existing ADR number and bump it by 1.

When the problem as well as proposed solution are well understood, changes should start with a draft pull request against master. The draft signals that work is underway. When the work is ready for feedback, hitting "Ready for Review" will signal to the maintainers to take a look.

Each stage of the process is aimed at creating feedback cycles which align contributors and maintainers to make sure:

• Contributors don’t waste their time implementing/proposing features which won’t land in master.
• Maintainers have the necessary context in order to support and review contributions.

Forking

Please note that Go requires code to live under absolute paths, which complicates forking. While my fork lives at https://github.com/ebuchman/tendermint, the code should never exist at $GOPATH/src/github.com/ebuchman/tendermint. Instead, we use git remote to add the fork as a new remote for the original repo, $GOPATH/src/github.com/tendermint/tendermint, and do all the work there.

For instance, to create a fork and work on a branch of it, I would:

• Create the fork on GitHub, using the fork button.
• Go to the original repo checked out locally (i.e. $GOPATH/src/github.com/tendermint/tendermint)
• git remote rename origin upstream
• git remote add origin git@github.com:ebuchman/basecoin.git

Now origin refers to my fork and upstream refers to the Tendermint version. So I can git push -u origin master to update my fork, and make pull requests to tendermint from there. Of course, replace ebuchman with your git handle.

To pull in updates from the origin repo, run

• git fetch upstream
• git rebase upstream/master (or whatever branch you want)

Dependencies

We use go modules to manage dependencies.

That said, the master branch of every Tendermint repository should just build with go get, which means they should be kept up-to-date with their dependencies so we can get away with telling people they can just go get our software.

Since some dependencies are not under our control, a third party may break our build, in which case we can fall back on go mod tidy. Even for dependencies under our control, go helps us to keep multiple repos in sync as they evolve. Anything with an executable, such as apps, tools, and the core, should use dep.

Run go list -u -m all to get a list of dependencies that may not be up-to-date.

When updating dependencies, please only update the particular dependencies you need. Instead of running go get -u=patch, which will update anything, specify exactly the dependency you want to update, eg. GO111MODULE=on go get -u github.com/tendermint/go-amino@master.

Protobuf

We use Protocol Buffers along with gogoproto to generate code for use across Tendermint Core.

For linting, checking breaking changes and generating proto stubs, we use buf. If you would like to run linting and check if the changes you have made are breaking then you will need to have docker running locally. Then the linting cmd will be make proto-lint and the breaking changes check will be make proto-check-breaking.

We use Docker to generate the protobuf stubs. To generate the stubs yourself, make sure docker is running then run make proto-gen.

Visual Studio Code

If you are a VS Code user, you may want to add the following to your .vscode/settings.json:

{
  "protoc": {
    "options": [
      "--proto_path=${workspaceRoot}/proto",
      "--proto_path=${workspaceRoot}/third_party/proto"
    ]
  }
}

Changelog

Every fix, improvement, feature, or breaking change should be made in a pull-request that includes an update to the CHANGELOG_PENDING.md file.

Changelog entries should be formatted as follows:

- [module] \#xxx Some description about the change (@contributor)

Here, module is the part of the code that changed (typically a top-level Go package), xxx is the pull-request number, and contributor is the author/s of the change.

It's also acceptable for xxx to refer to the relevant issue number, but pull-request numbers are preferred. Note this means pull-requests should be opened first so the changelog can then be updated with the pull-request's number. There is no need to include the full link, as this will be added automatically during release. But please include the backslash and pound, eg. \#2313.

Changelog entries should be ordered alphabetically according to the module, and numerically according to the pull-request number.

Changes with multiple classifications should be doubly included (eg. a bug fix that is also a breaking change should be recorded under both).

Breaking changes are further subdivided according to the APIs/users they impact. Any change that effects multiple APIs/users should be recorded multiply - for instance, a change to the Blockchain Protocol that removes a field from the header should also be recorded under CLI/RPC/Config since the field will be removed from the header in RPC responses as well.

Branching Model and Release

The main development branch is master.

Every release is maintained in a release branch named vX.Y.Z.

Pending minor releases have long-lived release candidate ("RC") branches. Minor release changes should be merged to these long-lived RC branches at the same time that the changes are merged to master.

Note all pull requests should be squash merged except for merging to a release branch (named vX.Y). This keeps the commit history clean and makes it easy to reference the pull request where a change was introduced.

Development Procedure

The latest state of development is on master, which must never fail make test. Never force push master, unless fixing broken git history (which we rarely do anyways).

To begin contributing, create a development branch either on github.com/tendermint/tendermint, or your fork (using git remote add origin).

Make changes, and before submitting a pull request, update the CHANGELOG_PENDING.md to record your change. Also, run either git rebase or git merge on top of the latest master. (Since pull requests are squash-merged, either is fine!)

Update the UPGRADING.md if the change you've made is breaking and the instructions should be in place for a user on how he/she can upgrade it's software (ABCI application, Tendermint-based blockchain, light client, wallet).

Once you have submitted a pull request label the pull request with either R:minor, if the change should be included in the next minor release, or R:major, if the change is meant for a major release.

Sometimes (often!) pull requests get out-of-date with master, as other people merge different pull requests to master. It is our convention that pull request authors are responsible for updating their branches with master. (This also means that you shouldn't update someone else's branch for them; even if it seems like you're doing them a favor, you may be interfering with their git flow in some way!)

Merging Pull Requests

It is also our convention that authors merge their own pull requests, when possible. External contributors may not have the necessary permissions to do this, in which case, a member of the core team will merge the pull request once it's been approved.

Before merging a pull request:

• Ensure pull branch is up-to-date with a recent master (GitHub won't let you merge without this!)
• Run make test to ensure that all tests pass
• Squash merge pull request

Pull Requests for Minor Releases

If your change should be included in a minor release, please also open a PR against the long-lived minor release candidate branch (e.g., rc1/v0.33.5) immediately after your change has been merged to master.

You can do this by cherry-picking your commit off master:

$ git checkout rc1/v0.33.5
$ git checkout -b {new branch name}
$ git cherry-pick {commit SHA from master}
# may need to fix conflicts, and then use git add and git cherry-pick --continue
$ git push origin {new branch name}

After this, you can open a PR. Please note in the PR body if there were merge conflicts so that reviewers can be sure to take a thorough look.

Git Commit Style

We follow the Go style guide on commit messages. Write concise commits that start with the package name and have a description that finishes the sentence "This change modifies Tendermint to...". For example,

cmd/debug: execute p.Signal only when p is not nil

[potentially longer description in the body]

Fixes #nnnn

Each PR should have one commit once it lands on master; this can be accomplished by using the "squash and merge" button on Github. Be sure to edit your commit message, though!

Release procedure

A note about backport branches

Tendermint's master branch is under active development. Releases are specified using tags and are built from long-lived "backport" branches. Each release "line" (e.g. 0.34 or 0.33) has its own long-lived backport branch, and the backport branches have names like v0.34.x or v0.33.x (literally, x; it is not a placeholder in this case).

As non-breaking changes land on master, they should also be backported (cherry-picked) to these backport branches.

We use Mergify's backport feature to automatically backport to the needed branch. There should be a label for any backport branch that you'll be targeting. To notify the bot to backport a pull request, mark the pull request with the label S:backport-to-<backport_branch>. Once the original pull request is merged, the bot will try to cherry-pick the pull request to the backport branch. If the bot fails to backport, it will open a pull request. The author of the original pull request is responsible for solving the conflicts and merging the pull request.

Creating a backport branch

If this is the first release candidate for a major release, you get to have the honor of creating the backport branch!

Note that, after creating the backport branch, you'll also need to update the tags on master so that go mod is able to order the branches correctly. You should tag master with a "dev" tag that is "greater than" the backport branches tags. See #6072 for more context.

In the following example, we'll assume that we're making a backport branch for the 0.35.x line.

1. Start on master
2. Create the backport branch: git checkout -b v0.35.x
3. Go back to master and tag it as the dev branch for the next major release and push it back up: git tag -a v0.36.0-dev; git push v0.36.0-dev
4. Create a new workflow to run the e2e nightlies for this backport branch. (See https://github.com/tendermint/tendermint/blob/master/.github/workflows/e2e-nightly-34x.yml for an example.)

Release candidates

Before creating an official release, especially a major release, we may want to create a release candidate (RC) for our friends and partners to test out. We use git tags to create RCs, and we build them off of backport branches.

Tags for RCs should follow the "standard" release naming conventions, with -rcX at the end (for example, v0.35.0-rc0).

(Note that branches and tags cannot have the same names, so it's important that these branches have distinct names from the tags/release names.)

If this is the first RC for a major release, you'll have to make a new backport branch (see above). Otherwise:

1. Start from the backport branch (e.g. v0.35.x).
2. Run the integration tests and the e2e nightlies (which can be triggered from the Github UI; e.g., https://github.com/tendermint/tendermint/actions/workflows/e2e-nightly-34x.yml).
3. Prepare the changelog:
   • Move the changes included in CHANGELOG_PENDING.md into CHANGELOG.md.
   • Run python ./scripts/linkify_changelog.py CHANGELOG.md to add links for all PRs
   • Ensure that UPGRADING.md is up-to-date and includes notes on any breaking changes or other upgrading flows.
   • Bump TMVersionDefault version in version.go
   • Bump P2P and block protocol versions in version.go, if necessary
   • Bump ABCI protocol version in version.go, if necessary
4. Open a PR with these changes against the backport branch.
5. Once these changes have landed on the backport branch, be sure to pull them back down locally.
6. Once you have the changes locally, create the new tag, specifying a name and a tag "message": git tag -a v0.35.0-rc0 -m "Release Candidate v0.35.0-rc0
7. Push the tag back up to origin: git push origin v0.35.0-rc0 Now the tag should be available on the repo's releases page.
8. Future RCs will continue to be built off of this branch.

Note that this process should only be used for "true" RCs-- release candidates that, if successful, will be the next release. For more experimental "RCs," create a new, short-lived branch and tag that instead.

Major release

This major release process assumes that this release was preceded by release candidates. If there were no release candidates, begin by creating a backport branch, as described above.

1. Start on the backport branch (e.g. v0.35.x)
2. Run integration tests and the e2e nightlies.
3. Prepare the release:
   • "Squash" changes from the changelog entries for the RCs into a single entry, and add all changes included in CHANGELOG_PENDING.md. (Squashing includes both combining all entries, as well as removing or simplifying any intra-RC changes. It may also help to alphabetize the entries by package name.)
   • Run python ./scripts/linkify_changelog.py CHANGELOG.md to add links for all PRs
   • Ensure that UPGRADING.md is up-to-date and includes notes on any breaking changes or other upgrading flows.
   • Bump TMVersionDefault version in version.go
   • Bump P2P and block protocol versions in version.go, if necessary
   • Bump ABCI protocol version in version.go, if necessary
4. Open a PR with these changes against the backport branch.
5. Once these changes are on the backport branch, push a tag with prepared release details. This will trigger the actual release v0.35.0.
   • git tag -a v0.35.0 -m 'Release v0.35.0'
   • git push origin v0.35.0
6. Make sure that master is updated with the latest CHANGELOG.md, CHANGELOG_PENDING.md, and UPGRADING.md.

Minor release (point releases)

Minor releases are done differently from major releases: They are built off of long-lived backport branches, rather than from master. As non-breaking changes land on master, they should also be backported (cherry-picked) to these backport branches.

Minor releases don't have release candidates by default, although any tricky changes may merit a release candidate.

To create a minor release:

1. Checkout the long-lived backport branch: git checkout v0.35.x
2. Run integration tests (make test_integrations) and the nightlies.
3. Check out a new branch and prepare the release:
   • Copy CHANGELOG_PENDING.md to top of CHANGELOG.md
   • Run python ./scripts/linkify_changelog.py CHANGELOG.md to add links for all issues
   • Run bash ./scripts/authors.sh to get a list of authors since the latest release, and add the GitHub aliases of external contributors to the top of the CHANGELOG. To lookup an alias from an email, try bash ./scripts/authors.sh <email>
   • Reset the CHANGELOG_PENDING.md
   • Bump the ABCI version number, if necessary. (Note that ABCI follows semver, and that ABCI versions are the only versions which can change during minor releases, and only field additions are valid minor changes.)
4. Open a PR with these changes that will land them back on v0.35.x
5. Once this change has landed on the backport branch, make sure to pull it locally, then push a tag.
   • git tag -a v0.35.1 -m 'Release v0.35.1'
   • git push origin v0.35.1
6. Create a pull request back to master with the CHANGELOG & version changes from the latest release.
   • Remove all R:minor labels from the pull requests that were included in the release.
   • Do not merge the backport branch into master.

Testing

Unit tests

Unit tests are located in _test.go files as directed by the Go testing package. If you're adding or removing a function, please check there's a TestType_Method test for it.

Run: make test

Integration tests

Integration tests are also located in _test.go files. What differentiates them is a more complicated setup, which usually involves setting up two or more components.

Run: make test_integrations

End-to-end tests

End-to-end tests are used to verify a fully integrated Tendermint network.

See README for details.

Run:

cd test/e2e && \
  make && \
  ./build/runner -f networks/ci.toml

Model-based tests (ADVANCED)

NOTE: if you're just submitting your first PR, you won't need to touch these most probably (99.9%).

For components, that have been formally verified using TLA+, it may be possible to generate tests using a combination of the Apalache Model Checker and tendermint-rs testgen util.

Now, I know there's a lot to take in. If you want to learn more, check out this video by Andrey Kupriyanov & Igor Konnov.

At the moment, we have model-based tests for the light client, located in the ./light/mbt directory.

Run: cd light/mbt && go test

Fuzz tests (ADVANCED)

NOTE: if you're just submitting your first PR, you won't need to touch these most probably (99.9%).

Fuzz tests can be found inside the ./test/fuzz directory. See README.md for details.

Run: cd test/fuzz && make fuzz-{PACKAGE-COMPONENT}

Jepsen tests (ADVANCED)

NOTE: if you're just submitting your first PR, you won't need to touch these most probably (99.9%).

Jepsen tests are used to verify the linearizability property of the Tendermint consensus. They are located in a separate repository -> https://github.com/tendermint/jepsen. Please refer to its README for more information.

RPC Testing

If you contribute to the RPC endpoints it's important to document your changes in the Openapi file.

To test your changes you must install nodejs and run:

npm i -g dredd
make build-linux build-contract-tests-hooks
make contract-tests

WARNING: these are currently broken due to https://github.com/apiaryio/dredd not supporting complete OpenAPI 3.

This command will popup a network and check every endpoint against what has been documented.