kubernetes cluster #22

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kubernetes-bundle

The kubernetes-bundle allows you to deploy the many services of Kubernetes to a cloud environment and get started using the Kubernetes technology quickly.

Kubernetes

Kubernetes is an open source system for managing containerized applications. Kubernetes uses Docker to run containerized applications.

Juju TL;DR

The Juju system provides provisioning and orchestration across a variety of clouds and bare metal. A juju bundle describes collection of services and how they interrelate. juju quickstart allows you to bootstrap a deployment environment and deploy a bundle.

Dive in!

Install Juju Quickstart

You will need to install the Juju client and juju-quickstart as pre-requisites. To deploy the bundle use juju-quickstart which runs on Mac OS (brew install juju-quickstart) or Ubuntu (apt-get install juju-quickstart).

Deploy Kubernetes Bundle

Deploy Kubernetes onto any cloud and orchestrated directly in the Juju Graphical User Interface using juju quickstart:

juju quickstart u/kubernetes/kubernetes-cluster

The command above does few things for you:

  • Starts a curses based gui for managing your cloud or MAAS credentials
  • Looks for a bootstrapped deployment environment, and bootstraps if required. This will launch a bootstrap node in your chosen deployment environment (machine 0).
  • Deploys the Juju GUI to your environment onto the bootstrap node.
  • Provisions 4 machines, and deploys the Kubernetes services on top of them (Kubernetes-master, two Kubernetes minions using flannel, and etcd).
  • Orchestrates the relations among the services, and exits.

Now you should have a running Kubernetes. Run juju status --format=oneline to see the address of the kubernetes-master unit.

For further reading on Juju Quickstart

Using the Kubernetes Client

You'll need the Kubernetes command line client, kubectl to interact with the created cluster. The kubectl command is installed on the kubernetes-master charm. If you want to work with the cluster from your computer you will need to install the binary locally (see instructions below).

You can access kubectl by a number ways using juju.

via juju run:

juju run --service kubernetes-master/0 "sudo kubectl get nodes"

via juju ssh:

juju ssh kubernetes-master/0 -t "sudo kubectl get nodes"

You may also juju ssh kubernetes-master/0 and call kubectl from that machine.

See the kubectl documentation for more details of what can be done with the command line tool.

Scaling up the cluster

You can add capacity by adding more Docker units:

 juju add-unit docker

Known Limitations

Kubernetes currently has several platform specific functionality. For example load balancers and persistence volumes only work with the Google Compute provider at this time.

The Juju integration uses the Kubernetes null provider. This means external load balancers and storage can't be directly driven through Kubernetes config files at this time. We look forward to adding these capabilities to the charms.

More about the components the bundle deploys

Kubernetes master

The master controls the Kubernetes cluster. It manages for the worker nodes and provides the primary interface for control by the user.

Kubernetes minion

The minions are the servers that perform the work. Minions must communicate with the master and run the workloads that are assigned to them.

Flannel-docker

Flannel provides individual subnets for each machine in the cluster by creating a software defined networking.

Docker

An open platform for distributed applications for developers and sysadmins.

Etcd

Etcd persists state for Flannel and Kubernetes. It is a distributed key-value store with an http interface.

For further information on getting started with Juju

Juju has complete documentation with regard to setup, and cloud configuration on it's own documentation site.

Installing the kubectl outside of kubernetes-master machine

Download the Kubernetes release from: https://github.com/GoogleCloudPlatform/kubernetes/releases and extract the release, you can then just directly use the cli binary at ./kubernetes/platforms/linux/amd64/kubectl

You'll need the address of the kubernetes-master as environment variable :

juju status kubernetes-master/0

Grab the public-address there and export it as KUBERNETES_MASTER environment variable :

export KUBERNETES_MASTER=$(juju status --format=oneline kubernetes-master | cut -d' ' -f3):8080

And now you can run kubectl on the command line :

kubectl get nodes

See the kubectl documentation for more details of what can be done with the command line tool.

Hacking on the kubernetes-bundle and associated charms

The Kubernetes project now contains the kubernetes-master and kubernetes and bundles.

Current and Most Complete Information

More information about the Kubernetes project or check out the Kubernetes Documentation for more details about the Kubernetes concepts and terminology.

Having a problem? Check the Kubernetes issues database for related issues.

Bundle configuration

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