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How to get started, and achieve tasks, using Kubernetes

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Juju

Juju makes it easy to deploy Kubernetes by provisioning, installing and configuring all the systems in the cluster. Once deployed the cluster can easily scale up with one command to increase the cluster size.

The Juju Kubernetes work is curated by a very small group of community members. Let us know how we are doing. If you find any problems please open an issue at the kubernetes project and tag the issue with “juju” so we can find them.

Prerequisites

Note: If you’re running kube-up, on Ubuntu - all of the dependencies will be handled for you. You may safely skip to the section: Launch a Kubernetes Cluster

On Ubuntu

Install the Juju client

This documentation focuses on the Juju 2.0 release which will be promoted to stable during the April 2016 release cycle.

To paraphrase, on your local Ubuntu system:

sudo add-apt-repository ppa:juju/devel
sudo apt-get update
sudo apt-get install juju2

If you are using another distro/platform - please consult the getting started guide to install the Juju dependencies for your platform.

With Docker

If you are not using Ubuntu or prefer the isolation of Docker, you may run the following:

While this is a common target, the charmbox flavors of images are unofficial, and should be treated as experimental. If you encounter any issues turning up the Kubernetes cluster with charmbox, please file a bug on the charmbox issue tracker.

mkdir ~/.juju2
sudo docker run -v ~/.juju2:/home/ubuntu/.local/share/juju -ti jujusolutions/charmbox:devel

Configure Juju to point a cloud

At this point you have access to the Juju client. Before you can deploy a cluster you have to configure the credentials for the Juju cloud provider.

Juju supports a wide variety of public clouds to set up the credentials for your chosen cloud see the cloud setup page.

After configuration is complete test your setup with a juju bootstrap command:
juju bootstrap $cloudname $cloudtype you are ready to launch the Kubernetes cluster.

Launch a Kubernetes cluster

You will need to export the KUBERNETES_PROVIDER environment variable before bringing up the cluster.

export KUBERNETES_PROVIDER=juju
cluster/kube-up.sh

If this is your first time running the kube-up.sh script, it will attempt to install the required dependencies to get started with Juju.

Next it will deploy two nodes of Kubernetes, 1 unit of etcd, and network the units so containers on different hosts can communicate with each other.

Exploring the cluster

The juju status command provides information about each unit in the cluster:

$ juju status

... (omitted for brevity)

[Units]
ID           WORKLOAD-STATE AGENT-STATE VERSION   MACHINE PORTS             PUBLIC-ADDRESS MESSAGE
etcd/0       active         idle        2.0-beta2 1                         54.146.50.29   Etcd leader running
kubernetes/0 active         idle        2.0-beta2 2       6443/tcp,8088/tcp 54.205.204.227 Kubernetes follower running
kubernetes/1 active         idle        2.0-beta2 3       6443/tcp,8088/tcp 54.145.57.114  Kubernetes leader running

... (omitted for brevity)

Run some containers!

The kubectl file, the TLS certificates along with the configuration are all available on the Kubernetes leader unit. Fetch the kubectl package so you can run commands on the new Kuberntetes cluster.

Use the juju status command to figure out which Kubernetes unit is the leader and copy the file from the leader:

juju scp kubernetes/1:kubectl_package.tar.gz .
tar xvfz kubectl_package.tar.gz
kubectl --kubeconfig config get pods

If you are not on a Linux amd64 host system, you will need to find or build a kubectl binary package for your architecture.

Put the config file in the home directory so you don’t have to specify it on the command line each time. The default location is ${HOME}/.kube/config.

No pods will be available before starting a container:

kubectl get pods
NAME READY STATUSRESTARTS   AGE

kubectl get replicationcontrollers
CONTROLLER  CONTAINER(S)  IMAGE(S)  SELECTOR  REPLICAS

We’ll follow the aws-coreos example. Create a pod manifest: pod.json

{
  "apiVersion": "v1",
  "kind": "Pod",
  "metadata": {
"name": "hello",
"labels": {
  "name": "hello",
  "environment": "testing"
}
  },
  "spec": {
"containers": [{
  "name": "hello",
  "image": "quay.io/kelseyhightower/hello",
  "ports": [{
"containerPort": 80,
"hostPort": 80
  }]
}]
  }
}

Create the pod with kubectl:

kubectl create -f pod.json

Get info on the pod:

kubectl get pods

To test the hello app, we need to locate which node is hosting the container. We can use juju run and juju status commands to find our hello app.

Exit out of our ssh session and run:

juju run --unit kubernetes/0 "docker ps -n=1"
...
juju run --unit kubernetes/1 "docker ps -n=1"
CONTAINER IDIMAGE  COMMAND CREATED STATUS  PORTS   NAMES
02beb61339d8quay.io/kelseyhightower/hello:latest   /hello  About an hour ago   Up About an hourk8s_hello....

We see “kubernetes/1” has our container, expose the kubernetes charm and open port 80:

juju run --unit kubernetes/1 "open-port 80"
juju expose kubernetes
sudo apt-get install curl
curl $(juju status --format=oneline kubernetes/1 | cut -d' ' -f3)

Finally delete the pod:

juju ssh kubernetes/0
kubectl delete pods hello

## Scale up cluster

Want larger Kubernetes nodes? It is easy to request different sizes of cloud resources from Juju by using constraints. You can increase the amount of CPU or memory (RAM) in any of the systems requested by Juju. This allows you to fine tune th Kubernetes cluster to fit your workload. Use flags on the bootstrap command or as a separate juju constraints command. Look to the Juju documentation for machine constraints details.

Scale out cluster

Need more clusters? Juju makes it easy to add units of a charm:

juju add-unit kubernetes

Or multiple units at one time:

juju add-unit -n3 kubernetes

Tear down cluster

We recommend that you use the kube-down.sh command when you are done using the cluster, as it properly brings down the cloud and removes some of the build directories.

./kube-down.sh

Alternately if you want stop the servers you can destroy your current Juju environment. Use the juju env command to get the current environment name:

juju kill-controller `juju env`

More Info

Juju works with charms and bundles to deploy solutions. The code that stands up a Kubernetes cluster is done in the charm code. The charm is built from using a layered approach to keep the code smaller and more focused on the operations of Kubernetes.

The Kubernetes layer and bundles can be found in the kubernetes project on github.com:

Cloud compatibility

Juju runs natively against a variety of public cloud providers. Juju currently works with Amazon Web Service, Windows Azure, DigitalOcean, Google Compute Engine, HP Public Cloud, Joyent, LXC, any OpenStack deployment, Vagrant, and Vmware vSphere.

If you do not see your favorite cloud provider listed many clouds with ssh access can be configured for manual provisioning.

Support Level

IaaS Provider Config. Mgmt OS Networking Docs Conforms Support Level
AWS Juju Ubuntu flannel docs   Community ( @whit, @matt, @chuck )
OpenStack/HPCloud Juju Ubuntu flannel docs   Community ( @whit, @matt, @chuck )
Joyent Juju Ubuntu flannel docs   Community ( @whit, @matt, @chuck )

For support level information on all solutions, see the Table of solutions chart.

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