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Getting started with Juju

Juju handles provisioning machines and deploying complex systems to a wide number of clouds, supporting service orchestration once the bundle of services has been deployed.

Table of Contents

• Prerequisites
  • On Ubuntu
  • With Docker
• Launch Kubernetes cluster
• Exploring the cluster
• Run some containers!
• Scale out cluster
• Launch the "k8petstore" example app
• Tear down cluster
• More Info
  • Cloud compatibility

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 Kubernetes Cluster

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

Kubernetes releases can be downloaded from this page.

You will need to have the Kubernetes tools compiled before launching the cluster

make all WHAT=cmd/kubectl export KUBERNETES_PROVIDER=juju cluster/kube-up.sh

If this is your first time running the kube-up.sh script, it will install the required predependencies to get started with Juju, additionally it will launch a curses based configuration utility allowing you to select your cloud provider and enter the proper access credentials.

Next it will deploy the Kubernetes master, etcd, 2 nodes with flannel based Software Defined Networking.

Exploring the cluster

Juju status provides information about each unit in the cluster:

juju status --format=oneline - docker/0: 52.4.92.78 (started) - flannel-docker/0: 52.4.92.78 (started) - kubernetes/0: 52.4.92.78 (started) - docker/1: 52.6.104.142 (started) - flannel-docker/1: 52.6.104.142 (started) - kubernetes/1: 52.6.104.142 (started) - etcd/0: 52.5.216.210 (started) 4001/tcp - juju-gui/0: 52.5.205.174 (started) 80/tcp, 443/tcp - kubernetes-master/0: 52.6.19.238 (started) 8080/tcp

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 NAME READY STATUS RESTARTS 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. Better tooling for using juju to introspect container is in the works but we can use 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 node units like so:

juju add-unit docker # creates unit docker/2, kubernetes/2, docker-flannel/2

Launch the "k8petstore" example app

The k8petstore example is available as a juju action.

juju action do kubernetes-master/0

Note: this example includes curl statements to exercise the app, which automatically generates "petstore" transactions written to redis, and allows you to visualize the throughput in your browser.

Tear down cluster

./kube-down.sh

or

juju destroy-environment --force juju env

More Info

Kubernetes Bundle on Github

• Bundle Repository
  • Kubernetes master charm
  • Kubernetes node charm
• Bundle Documentation
• More about Juju

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.