Kubernetes

Kubernetes is an open source implementation of container cluster management.

Kubernetes Design Document - Kubernetes @ Google I/O 2014

Kubernetes can run anywhere!

However, initial development was done on GCE and so our instructions and scripts are built around that. If you make it work on other infrastructure please let us know and contribute instructions/code.

Kubernetes is in pre-production beta!

While the concepts and architecture in Kubernetes represent years of experience designing and building large scale cluster manager at Google, the Kubernetes project is still under heavy development. Expect bugs, design and API changes as we bring it to a stable, production product over the coming year.

Contents

• Getting Started Guides
  • Google Compute Engine
  • Vagrant
  • Locally
  • CoreOS
  • Fedora
  • vSphere
  • Microsoft Azure
  • Rackspace
  • Circle CI
  • Digital Ocean
  • OpenStack
• kubecfg command line tool
• Kubernetes API Documentation
• Kubernetes Client Libraries
• Discussion and Community Support
• Hacking on Kubernetes
• Hacking on Kubernetes Salt configuration

Where to go next?

Check out examples of Kubernetes in action, and community projects in the larger ecosystem:

• Detailed example application
• Example of dynamic updates
• Cluster monitoring with heapster and cAdvisor
• Community projects

Or fork and start hacking!

Community, discussion and support

If you have questions or want to start contributing please reach out. We don't bite!

The Kubernetes team is hanging out on IRC on the #google-containers room on freenode.net. We also have the google-containers Google Groups mailing list.

If you are a company and are looking for a more formal engagement with Google around Kubernetes and containers at Google as a whole, please fill out this form. and we'll be in touch.

Development

Go development environment

Kubernetes is written in Go programming language. If you haven't set up Go development environment, please follow this instruction to install go tool and set up GOPATH. Ensure your version of Go is at least 1.3.

Put kubernetes into GOPATH

We highly recommend to put kubernetes' code into your GOPATH. For example, the following commands will download kubernetes' code under the current user's GOPATH (Assuming there's only one directory in GOPATH.):

$ echo $GOPATH
/home/user/goproj
$ mkdir -p $GOPATH/src/github.com/GoogleCloudPlatform/
$ cd $GOPATH/src/github.com/GoogleCloudPlatform/
$ git clone git@github.com:GoogleCloudPlatform/kubernetes.git

The commands above will not work if there are more than one directory in $GOPATH.

(Obviously, clone your own fork of Kubernetes if you plan to do development.)

godep and dependency management

Kubernetes uses 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 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.
2. Create a new GOPATH for your tools and install godep:

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:

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

Using godep

Here is a quick summary of godep. godep helps manage third party dependencies by copying known versions into Godep/_workspace. You can use godep in three ways:

1. Use godep to call your go commands. For example: godep go test ./...
2. Use godep to modify your $GOPATH so that other tools know where to find the dependencies. Specifically: export GOPATH=$GOPATH:$(godep path)
3. Use godep to copy the saved versions of packages into your $GOPATH. This is done with godep restore.

We recommend using options #1 or #2.

Hooks

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

NOTE: The ../.. part seems odd but is correct, since the newly created links will be 2 levels down the tree.

cd kubernetes
ln -s ../../hooks/prepare-commit-msg .git/hooks/prepare-commit-msg
ln -s ../../hooks/commit-msg .git/hooks/commit-msg

Unit tests

cd kubernetes
hack/test-go.sh

Alternatively, you could also run:

cd kubernetes
godep go test ./...

If you only want to run unit tests in one package, you could run godep go test under the package directory. For example, the following commands will run all unit tests in package kubelet:

$ cd kubernetes # step into kubernetes' directory.
$ cd pkg/kubelet
$ godep go test
# some output from unit tests
PASS
ok      github.com/GoogleCloudPlatform/kubernetes/pkg/kubelet   0.317s

Coverage

cd kubernetes
godep go tool cover -html=target/c.out

Integration tests

You need an etcd somewhere in your path. To get from head:

go get github.com/coreos/etcd
go install github.com/coreos/etcd
sudo ln -s "$GOPATH/bin/etcd" /usr/bin/etcd
# Or just use the packaged one:
sudo ln -s "$REPO_ROOT/target/bin/etcd" /usr/bin/etcd

cd kubernetes
hack/test-integration.sh

End-to-End tests

You can run an end-to-end test which will bring up a master and two minions, perform some tests, and then tear everything down. Make sure you have followed the getting started steps for your chosen cloud platform (which might involve changing the KUBERNETES_PROVIDER environment variable to something other than "gce".

cd kubernetes
hack/e2e-test.sh

Pressing control-C should result in an orderly shutdown but if something goes wrong and you still have some VMs running you can force a cleanup with the magical incantation:

hack/e2e-test.sh 1 1 1

Testing out flaky tests

Instructions here

Add/Update dependencies

Kubernetes uses godep to manage dependencies. To add or update a package, please follow the instructions on godep's document.

To add a new package foo/bar:

• Download foo/bar into the first directory in GOPATH: go get foo/bar.
• Change code in kubernetes to use foo/bar.
• Run godep save ./... under kubernetes' root directory.

To update a package foo/bar:

• Update the package with go get -u foo/bar.
• Change code in kubernetes accordingly if necessary.
• Run godep update foo/bar.

Keeping your development fork in sync

One time after cloning your forked repo:

git remote add upstream https://github.com/GoogleCloudPlatform/kubernetes.git

Then each time you want to sync to upstream:

git fetch upstream
git rebase upstream/master

Regenerating the API documentation

cd kubernetes/api
sudo docker build -t kubernetes/raml2html .
sudo docker run --name="docgen" kubernetes/raml2html
sudo docker cp docgen:/data/kubernetes.html .

View the API documentation using htmlpreview (works on your fork, too):

http://htmlpreview.github.io/?https://github.com/GoogleCloudPlatform/kubernetes/blob/master/api/kubernetes.html