development.md

Development Guide

This document is intended to be the canonical source of truth for things like supported toolchain versions for building Kubernetes. If you find a requirement that this doc does not capture, please submit an issue on github. If you find other docs with references to requirements that are not simply links to this doc, please submit an issue.

This document is intended to be relative to the branch in which it is found. It is guaranteed that requirements will change over time for the development branch, but release branches of Kubernetes should not change.

Building Kubernetes with Docker

Official releases are built using Docker containers. To build Kubernetes using Docker please follow [these instructions] (http://releases.k8s.io/HEAD/build-tools/README.md).

Building Kubernetes on a local OS/shell environment

Many of the Kubernetes development helper scripts rely on a fairly up-to-date GNU tools environment, so most recent Linux distros should work just fine out-of-the-box. Note that Mac OS X ships with somewhat outdated BSD-based tools, some of which may be incompatible in subtle ways, so we recommend [replacing those with modern GNU tools] (https://www.topbug.net/blog/2013/04/14/install-and-use-gnu-command-line-tools-in-mac-os-x/).

Go development environment

Kubernetes is written in the Go programming language. To build Kubernetes without using Docker containers, you'll need a Go development environment. Builds for Kubernetes 1.0 - 1.2 require Go version 1.4.2. Builds for Kubernetes 1.3 and higher require Go version 1.6.0. If you haven't set up a Go development environment, please follow these instructions to install the go tools.

Set up your GOPATH and add a path entry for go binaries to your PATH. Typically added to your ~/.profile:

export GOPATH=$HOME/go
export PATH=$PATH:$GOPATH/bin

Godep dependency management

Kubernetes build and test scripts use godep to manage dependencies.

Install godep

Ensure that mercurial is installed on your system. (some of godep's dependencies use the mercurial source control system). Use apt-get install mercurial or yum install mercurial on Linux, or brew.sh on OS X, or download directly from mercurial.

Install godep and go-bindata (may require sudo):

go get -u github.com/tools/godep
go get -u github.com/jteeuwen/go-bindata/go-bindata

Note: At this time, godep version >= v63 is known to work in the Kubernetes project.

To check your version of godep:

$ godep version
godep v74 (linux/amd64/go1.6.2)

Developers planning to managing dependencies in the vendor/ tree may want to explore alternative environment setups. See using godep to manage dependencies.

Local build using make

To build Kubernetes using your local Go development environment (generate linux binaries):

        make

You may pass build options and packages to the script as necessary. For example, to build with optimizations disabled for enabling use of source debug tools:

        make GOGCFLAGS="-N -l"

To build binaries for all platforms:

        make cross

How to update the Go version used to test & build k8s

The kubernetes project tries to stay on the latest version of Go so it can benefit from the improvements to the language over time and can easily bump to a minor release version for security updates.

Since kubernetes is mostly built and tested in containers, there are a few unique places you need to update the go version.

• The image for cross compiling in build-tools/build-image/cross/. The VERSION file and Dockerfile.
• Update dockerized-e2e-runner.sh to run a kubekins-e2e with the desired go version, which requires pushing e2e-image and test-image images that are FROM the desired go version.
• The docker image being run in gotest-dockerized.sh.
• The cross tag KUBE_BUILD_IMAGE_CROSS_TAG in build-tools/common.sh

Workflow

Below, we outline one of the more common git workflows that core developers use. Other git workflows are also valid.

Visual overview

Fork the main repository

1. Go to https://github.com/kubernetes/kubernetes
2. Click the "Fork" button (at the top right)

Clone your fork

The commands below require that you have $GOPATH set ($GOPATH docs). We highly recommend you put Kubernetes' code into your GOPATH. Note: the commands below will not work if there is more than one directory in your $GOPATH.

mkdir -p $GOPATH/src/k8s.io
cd $GOPATH/src/k8s.io
# Replace "$YOUR_GITHUB_USERNAME" below with your github username
git clone https://github.com/$YOUR_GITHUB_USERNAME/kubernetes.git
cd kubernetes
git remote add upstream 'https://github.com/kubernetes/kubernetes.git'

Create a branch and make changes

git checkout -b my-feature
# Make your code changes

Keeping your development fork in sync

git fetch upstream
git rebase upstream/master

Note: If you have write access to the main repository at github.com/kubernetes/kubernetes, you should modify your git configuration so that you can't accidentally push to upstream:

git remote set-url --push upstream no_push

Committing changes to your fork

Before committing any changes, please link/copy the pre-commit hook into your .git directory. This will keep you from accidentally committing non-gofmt'd Go code. This hook will also do a build and test whether documentation generation scripts need to be executed.

The hook requires both Godep and etcd on your PATH.

cd kubernetes/.git/hooks/
ln -s ../../hooks/pre-commit .

Then you can commit your changes and push them to your fork:

git commit
git push -f origin my-feature

Creating a pull request

1. Visit https://github.com/$YOUR_GITHUB_USERNAME/kubernetes
2. Click the "Compare & pull request" button next to your "my-feature" branch.
3. Check out the pull request process for more details

Note: If you have write access, please refrain from using the GitHub UI for creating PRs, because GitHub will create the PR branch inside the main repository rather than inside your fork.

When to retain commits and when to squash

Upon merge, all git commits should represent meaningful milestones or units of work. Use commits to add clarity to the development and review process.

Before merging a PR, squash any "fix review feedback", "typo", and "rebased" sorts of commits. It is not imperative that every commit in a PR compile and pass tests independently, but it is worth striving for. For mass automated fixups (e.g. automated doc formatting), use one or more commits for the changes to tooling and a final commit to apply the fixup en masse. This makes reviews much easier.

See Faster Reviews for more details.

Testing

Three basic commands let you run unit, integration and/or e2e tests:

cd kubernetes
make test # Run every unit test
make test WHAT=pkg/util/cache GOFLAGS=-v # Run tests of a package verbosely
make test-integration # Run integration tests, requires etcd
make test-e2e # Run e2e tests

See the testing guide and end-to-end tests for additional information and scenarios.

Regenerating the CLI documentation

hack/update-generated-docs.sh