k3s/docs/devel/development.md

<!-- BEGIN MUNGE: UNVERSIONED_WARNING -->

<!-- BEGIN STRIP_FOR_RELEASE -->

<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
     width="25" height="25">
<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
     width="25" height="25">
<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
     width="25" height="25">
<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
     width="25" height="25">
<img src="http://kubernetes.io/img/warning.png" alt="WARNING"
     width="25" height="25">

<h2>PLEASE NOTE: This document applies to the HEAD of the source tree</h2>

If you are using a released version of Kubernetes, you should
refer to the docs that go with that version.

<!-- TAG RELEASE_LINK, added by the munger automatically -->
<strong>
The latest release of this document can be found
[here](http://releases.k8s.io/release-1.2/docs/devel/development.md).

Documentation for other releases can be found at
[releases.k8s.io](http://releases.k8s.io).
</strong>
--

<!-- END STRIP_FOR_RELEASE -->

<!-- END MUNGE: UNVERSIONED_WARNING -->

# 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 file a bug.  If you find
other docs with references to requirements that are not simply links to this
doc, please file a bug.

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.

## Releases and Official Builds

Official releases are built in Docker containers.  Details are [here](http://releases.k8s.io/HEAD/build/README.md).  You can do simple builds and development with just a local Docker installation.  If you want to build go code locally outside of docker, please continue below.

## Go development environment

Kubernetes is written in the [Go](http://golang.org) programming language. If you haven't set up a Go development environment, please follow [these instructions](http://golang.org/doc/code.html) to install the go tools and set up a GOPATH.

### Go versions

Requires Go version 1.4.x or 1.5.x

## Git setup

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

### Visual overview

![Git workflow](git_workflow.png)

### 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](https://golang.org/doc/code.html#GOPATH)). 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`.

```sh
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

```sh
git checkout -b myfeature
# Make your code changes
```

### Keeping your development fork in sync

```sh
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:

```sh
git remote set-url --push upstream no_push
```

### Committing changes to your fork

Before committing any changes, please link/copy these pre-commit hooks into your .git
directory. This will keep you from accidentally committing non-gofmt'd go code.

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

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

```sh
git commit
git push -f origin myfeature
```

### Creating a pull request

1. Visit https://github.com/$YOUR_GITHUB_USERNAME/kubernetes
2. Click the "Compare and pull request" button next to your "myfeature" branch.
3. Check out the pull request [process](pull-requests.md) for more details

### 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](faster_reviews.md) for more details.

## godep and dependency management

Kubernetes uses [godep](https://github.com/tools/godep) to manage dependencies. It is not strictly required for building Kubernetes but it is required when managing dependencies under the Godeps/ tree, and is required by a number of the build and test scripts. Please make sure that ``godep`` is installed and in your ``$PATH``.

### Installing godep

There are many ways to build and host go binaries. Here is an easy way to get utilities like `godep` installed:

1) Ensure that [mercurial](http://mercurial.selenic.com/wiki/Download) 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](http://brew.sh) on OS X, or download
directly from mercurial.

2) Create a new GOPATH for your tools and install godep:

```sh
export GOPATH=$HOME/go-tools
mkdir -p $GOPATH
go get github.com/tools/godep
```

3) Add $GOPATH/bin to your path. Typically you'd add this to your ~/.profile:

```sh
export GOPATH=$HOME/go-tools
export PATH=$PATH:$GOPATH/bin
```

Note:
At this time, godep update in the Kubernetes project only works properly if your version of godep is < 54.

To check your version of godep:

```sh
$ godep version
godep v53 (linux/amd64/go1.5.3)
```

### Using godep

Here's a quick walkthrough of one way to use godeps to add or update a Kubernetes dependency into Godeps/\_workspace. For more details, please see the instructions in [godep's documentation](https://github.com/tools/godep).

1) Devote a directory to this endeavor:

_Devoting a separate directory is not required, but it is helpful to separate dependency updates from other changes._

```sh
export KPATH=$HOME/code/kubernetes
mkdir -p $KPATH/src/k8s.io/kubernetes
cd $KPATH/src/k8s.io/kubernetes
git clone https://path/to/your/fork .
# Or copy your existing local repo here. IMPORTANT: making a symlink doesn't work.
```

2) Set up your GOPATH.

```sh
# Option A: this will let your builds see packages that exist elsewhere on your system.
export GOPATH=$KPATH:$GOPATH
# Option B: This will *not* let your local builds see packages that exist elsewhere on your system.
export GOPATH=$KPATH
# Option B is recommended if you're going to mess with the dependencies.
```

3) Populate your new GOPATH.

```sh
cd $KPATH/src/k8s.io/kubernetes
godep restore
```

4) Next, you can either add a new dependency or update an existing one.

```sh
# To add a new dependency, do:
cd $KPATH/src/k8s.io/kubernetes
go get path/to/dependency
# Change code in Kubernetes to use the dependency.
godep save ./...

# To update an existing dependency, do:
cd $KPATH/src/k8s.io/kubernetes
go get -u path/to/dependency
# Change code in Kubernetes accordingly if necessary.
godep update path/to/dependency/...
```

_If `go get -u path/to/dependency` fails with compilation errors, instead try `go get -d -u path/to/dependency`
to fetch the dependencies without compiling them.  This can happen when updating the cadvisor dependency._


5) Before sending your PR, it's a good idea to sanity check that your Godeps.json file is ok by running `hack/verify-godeps.sh`

_If hack/verify-godeps.sh fails after a `godep update`, it is possible that a transitive dependency was added or removed but not
updated by godeps.  It then may be necessary to perform a `godep save ./...` to pick up the transitive dependency changes._

It is sometimes expedient to manually fix the /Godeps/godeps.json file to minimize the changes.

Please send dependency updates in separate commits within your PR, for easier reviewing.

6) If you updated the Godeps, please also update `Godeps/LICENSES` by running `hack/update-godep-licenses.sh`.

## Testing

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

```sh
cd kubernetes
hack/test-go.sh  # Run unit tests
hack/test-integration.sh  # Run integration tests, requires etcd
go run hack/e2e.go -v --build --up --test --down  # Run e2e tests
```

See the [testing guide](testing.md) for additional information and scenarios.

## Regenerating the CLI documentation

```sh
hack/update-generated-docs.sh
```


<!-- BEGIN MUNGE: GENERATED_ANALYTICS -->
[![Analytics](https://kubernetes-site.appspot.com/UA-36037335-10/GitHub/docs/devel/development.md?pixel)]()
<!-- END MUNGE: GENERATED_ANALYTICS -->