guide

Kubernetes Contributor Guide

Disclaimer

Hello! This is the starting point for our brand new contributor guide, currently underway as per issue#6102 and is in need of help. Please be patient, or fix a section below that needs improvement, and submit a pull request! Feel free to browse the open issues and file new ones, all feedback welcome!

Welcome

Welcome to Kubernetes! This document is the single source of truth for how to contribute to the code base. Please leave comments / suggestions if you find something is missing or incorrect.

Before you get started

Sign the CLA

Before you can contribute, you will need to sign the Contributor License Agreement.

Code of Conduct

Please make sure to read and observe our Code of Conduct.

Setting up your development environment

If you haven’t set up your environment, please find resources here.

Community Expectations and Roles

Kubernetes is a community project. Consequently, it is wholly dependent on its community to provide a productive, friendly and collaborative environment.

  • Read and review the Community Expectations for an understanding of code and review expectations.
  • See Community Membership for a list the various responsibilities of contributor roles. You are encouraged to move up this contributor ladder as you gain experience.

Your First Contribution

Have you ever wanted to contribute to the coolest cloud technology? We will help you understand the organization of the Kubernetes project and direct you to the best places to get started. You’ll be able to pick up issues, write code to fix them, and get your work reviewed and merged.

Please be aware that due to the large number of issues our triage team deals with, we cannot offer technical support in GitHub issues. If you have questions about the development process, feel free to jump into our Slack Channel or join our mailing list. You can also ask questions on ServerFault or Stack Overflow. The Kubernetes team scans Stack Overflow on a regular basis and will try to ensure your questions don’t go unanswered.

Find something to work on

Help is always welcome! For example, documentation (like the text you are reading now) can always use improvement. There’s always code that can be clarified and variables or functions that can be renamed or commented. There’s always a need for more test coverage. You get the idea - if you ever see something you think should be fixed, you should own it. Here is how you get started.

Find a good first topic

There are multiple repositories within the Kubernetes community and a full list of repositories can be found here. Each repository in the Kubernetes organization has beginner-friendly issues that provide a good first issue. For example, kubernetes/kubernetes has help wanted and good first issue labels for issues that should not need deep knowledge of the system. The good first issue label indicates that members have committed to providing extra assistance for new contributors. Read more here. Please note that while several of the repositories in the Kubernetes community have good first issue labels already, they are still being applied throughout the community.

Another good strategy is to find a documentation improvement, such as a missing/broken link, which will give you exposure to the code submission/review process without the added complication of technical depth. Please see Contributing below for the workflow.

Issue Assignment in Github

Often, new contributors ask to be assigned an issue they are willing to take on. Unfortunately, due to GitHub limitations we can only assign issues to org members or repo collaborators. Instead, please state in a comment that you intend to work on this issue and it will be assumed to be yours.

Learn about SIGs

Sig structure

You may have noticed that some repositories in the Kubernetes Organization are owned by Special Interest Groups, or SIGs. We organize the Kubernetes community into SIGs in order to improve our workflow and more easily manage what is a very large community project. The developers within each SIG have autonomy and ownership over that SIG’s part of Kubernetes.

Some SIGs also have their own CONTRIBUTING.md files, which may contain extra information or guidelines in addition to these general ones. These are located in the SIG-specific community directories. For example: the contributor’s guide for SIG CLI is located in the kubernetes/community repo, as /sig-cli/CONTRIBUTING.md.

Like everything else in Kubernetes, a SIG is an open, community, effort. Anybody is welcome to jump into a SIG and begin fixing issues, critiquing design proposals and reviewing code. SIGs have regular video meetings which everyone is welcome to. Each SIG has a kubernetes slack channel that you can join as well.

There is an entire SIG (sig-contributor-experience) devoted to improving your experience as a contributor. Contributing to Kubernetes should be easy. If you find a rough edge, let us know! Better yet, help us fix it by joining the SIG; just show up to one of the bi-weekly meetings.

Finding the appropriate SIG for your contribution and adding a SIG label will help you ask questions in the correct place and give your contribution higher visibility and a faster community response.

For Pull Requests, the automatically assigned reviewer will add a SIG label if you haven’t done so. See Open A Pull Request below.

For Issues, we are still working on a more automated workflow. Since SIGs do not directly map onto Kubernetes subrepositories, it may be difficult to find which SIG your contribution belongs in. Here is the list of SIGs. Determine which is most likely related to your contribution.

Example: if you are filing a CNI issue (that’s Container Networking Interface), you should choose the Network SIG. Add the SIG label in a comment like so:

/sig network

Follow the link in the SIG name column to reach each SIGs README. Most SIGs will have a set of GitHub Teams with tags that can be mentioned in a comment on issues and pull requests for higher visibility. If you are not sure about the correct SIG for an issue, you can try SIG-contributor-experience here, or ask in Slack.

File an Issue

Not ready to contribute code, but see something that needs work? While the community encourages everyone to contribute code, it is also appreciated when someone reports an issue (aka problem). Issues should be filed under the appropriate Kubernetes subrepository. Check the issue triage guide for more information.

Example: a documentation issue should be opened to kubernetes/website.

Make sure to adhere to the prompted submission guidelines while opening an issue.

Contributing

Kubernetes is open source, but many of the people working on it do so as their day job. In order to avoid forcing people to be “at work” effectively 247, we want to establish some semi-formal protocols around development. Hopefully, these rules make things go more smoothly. If you find that this is not the case, please complain loudly.

As a potential contributor, your changes and ideas are welcome at any hour of the day or night, weekdays, weekends, and holidays. Please do not ever hesitate to ask a question or send a pull request.

Our community guiding principles on how to create great code as a big group are found here.

Beginner focused information can be found below in Open a Pull Request and Code Review.

For quick reference on contributor resources, we have a handy contributor cheatsheet

Communication

It is best to contact your SIG for issues related to the SIG’s topic. Your SIG will be able to help you much more quickly than a general question would.

For general questions and troubleshooting, use the kubernetes standard lines of communication and work through the kubernetes troubleshooting guide.

GitHub workflow

To check out code to work on, please refer to this guide.

Open a Pull Request

Pull requests are often called simply “PR”. Kubernetes generally follows the standard github pull request process, but there is a layer of additional kubernetes specific (and sometimes SIG specific) differences:

The first difference you’ll see is that a bot will begin applying structured labels to your PR.

The bot may also make some helpful suggestions for commands to run in your PR to facilitate review. These /command options can be entered in comments to trigger auto-labeling and notifications. The command reference is here.

Common new contributor PR issues are:

  • not having correctly signed the CLA ahead of your first PR (see Sign the CLA section)
  • finding the right SIG or reviewer(s) for the PR (see Code Review section) and following any SIG or repository specific contributing guidelines (see Learn about SIGs section)
  • dealing with test cases which fail on your PR, unrelated to the changes you introduce (see Test Flakes)
  • Not following scalability good practices

Code Review

For a brief description of the importance of code review, please read On Code Review. There are two aspects of code review: giving and receiving.

To make it easier for your PR to receive reviews, consider the reviewers will need you to:

  • follow the project coding conventions
  • write good commit messages
  • break large changes into a logical series of smaller patches which individually make easily understandable changes, and in aggregate solve a broader issue
  • label PRs with appropriate SIGs and reviewers: to do this read the messages the bot sends you to guide you through the PR process

Reviewers, the people giving the review, are highly encouraged to revisit the Code of Conduct and must go above and beyond to promote a collaborative, respectful Kubernetes community. When reviewing PRs from others The Gentle Art of Patch Review suggests an iterative series of focuses which is designed to lead new contributors to positive collaboration without inundating them initially with nuances:

  • Is the idea behind the contribution sound?
  • Is the contribution architected correctly?
  • Is the contribution polished?

Testing

Testing is the responsibility of all contributors and is in part owned by all sigs, but is also coordinated by sig-testing.

The main testing overview document is here.

There are multiple types of tests in kubernetes. The location of the test code varies with type, as do the specifics of the environment needed to successfully run the test:

  • Unit: These confirm that a particular function behaves as intended. Golang includes a native ability for unit testing via the testing package. Unit test source code can be found adjacent to the corresponding source code within a given package. For example: functions defined in kubernetes/cmd/kubeadm/app/util/version.go will have unit tests in kubernetes/cmd/kubeadm/app/util/version_test.go. These are easily run locally by any developer on any OS.
  • Integration: These tests cover interactions of package components or interactions between kubernetes components and some other non-kubernetes system resource (eg: etcd). An example would be testing whether a piece of code can correctly store data to or retrieve data from etcd. Integration tests are stored in kubernetes/test/integration/. Running these can require the developer set up additional functionality on their development system.
  • End-to-end (“e2e”): These are broad tests of overall kubernetes system behavior and coherence. These are more complicated as they require a functional kubernetes cluster built from the sources to be tested. A separate document here details e2e testing and test cases themselves can be found in kubernetes/test/e2e/.
  • Conformance: These are a set of testcases, currently a subset of the integration/e2e tests, that the Architecture SIG has approved to define the core set of interoperable features that all Kubernetes deployments must support. For more information on Conformance tests please see the Conformance Testing Document.

Continuous integration will run these tests either as pre-submits on PRs, post-submits against master/release branches, or both. The results appear on testgrid.

sig-testing is responsible for that official infrastructure and CI. The associated automation is tracked in the test-infra repo. If you’re looking to run e2e tests on your own infrastructure, kubetest is the mechanism.

Security

Documentation

Issues Management or Triage

Have you ever noticed the total number of open issues? This number at any given time is typically high. Helping to manage or triage these open issues can be a great contribution to the Kubernetes project. This is also a great opportunity to learn about the various areas of the project. Refer to the Kubernetes Issue Triage Guidelines for more information.

Community

If you haven’t noticed by now, we have a large, lively, and friendly open-source community. We depend on new people becoming members and regular code contributors, so we would like you to come join us. To find out more about our community structure, different levels of membership and code contributors, please explore here.

Communication

Events

Kubernetes is the main focus of KubeCon + CloudNativeCon, held three times per year in China, Europe and in North America. Information about these and other community events is available on the CNCF events pages.

Meetups

We follow the general Cloud Native Computing Foundation guidelines for Meetups. You may also contact Paris Pittman via direct message on Kubernetes Slack (@paris) or by email (parispittman@google.com)

Mentorship

Please learn about our mentoring initiatives here.

Advanced Topics

This section includes things that need to be documented, but typical contributors do not need to interact with regularly.

  • OWNERS files - The Kubernetes organizations are managed with OWNERS files, which outline which parts of the code are owned by what groups.