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Getting start with Juju

Juju handles provisioning machines and deploying complex systems to a wide number of clouds.

Prerequisites

On Ubuntu

Install the Juju client on your local ubuntu system:

sudo add-apt-repository ppa:juju/stable
sudo apt-get update
sudo apt-get install juju-core juju-quickstart

With Docker

If you are not using ubuntu or prefer the isolation of docker, you may run the following:

mkdir ~/.juju
sudo docker run -v ~/.juju:/home/ubuntu/.juju -ti whitmo/jujubox:latest

At this point from either path you will have access to the juju quickstart command.

To set up the credentials for your chosen cloud run:

juju quickstart --constraints="mem=3.75G" -i

Follow the dialogue and choose save and use. Quickstart will now bootstrap the juju root node and setup the juju web based user interface.

Launch Kubernetes cluster

juju quickstart https://raw.githubusercontent.com/whitmo/bundle-kubernetes/master/bundles.yaml

First this command will start a curses based gui allowing you to set up credentials and other environmental settings for several different providers including Azure and AWS.

Next it will deploy the kubernetes master, etcd, 2 minions with flannel networking.

Exploring the cluster

Juju status provides information about each unit in the cluster:

juju status --format=oneline

- etcd/0: 52.0.74.109 (started)
- flannel/0: 52.0.149.150 (started)
- flannel/1: 52.0.185.81 (started)
- juju-gui/0: 52.1.150.81 (started)
- kubernetes/0: 52.0.149.150 (started)
- kubernetes/1: 52.0.185.81 (started)
- kubernetes-master/0: 52.1.120.142 (started)

You can use juju ssh to access any of the units:

juju ssh kubernetes-master/0

Run some containers!

kubectl is available on the kubernetes master node. We'll ssh in to launch some containers, but one could use kubectl locally setting KUBERNETES_MASTER to point at the ip of kubernetes-master/0.

No pods will be available before starting a container:

kubectl get pods
POD  CONTAINER(S)   IMAGE(S)   HOST  LABELS  STATUS

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

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

{
  "id": "hello",
  "kind": "Pod",
  "apiVersion": "v1beta1",
  "desiredState": {
    "manifest": {
      "version": "v1beta1",
      "id": "hello",
      "containers": [{
        "name": "hello",
        "image": "quay.io/kelseyhightower/hello",
        "ports": [{
          "containerPort": 80,
          "hostPort": 80
        }]
      }]
    }
  },
  "labels": {
    "name": "hello",
    "environment": "testing"
  }
}

Create the pod with kubectl:

kubectl create -f pod.json

Get info on the pod:

kubectl get pods

To test the hello app, we'll need to locate which minion is hosting the container. Better tooling for using juju to introspect container is in the works but for let'suse juju run and juju status 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 ID        IMAGE                                  COMMAND             CREATED             STATUS              PORTS               NAMES
02beb61339d8        quay.io/kelseyhightower/hello:latest   /hello              About an hour ago   Up About an hour                        k8s_hello....

We see kubernetes/1 has our container, we can 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-master/0
kubectl delete pods hello

Scale out cluster

We can add minion units like so:

juju add-unit flannel # creates unit flannel/2
juju add-unit kubernetes --to flannel/2

Tear down cluster

juju destroy-environment --force `juju env`

More Info

Kubernetes Bundle on Github

Cloud compatibility

Juju runs natively against a variety of cloud providers and can be made to work against many more using a generic manual provider.

Provider v0.8.1
AWS Pass
HPCloud Pass
OpenStack Pass
Joyent Pass
Azure TBD
Digital Ocean TBD
MAAS (bare metal) TBD
GCE TBD