Containerization

Part 1

What is a container ?

• A container image is a lightweight, stand-alone, executable package of a piece of software that includes everything needed to run it

Why run a whole VM

when you only need isolation ?

https://www.docker.com/what-container

https://docs.docker.com/engine/userguide/eng-image/baseimages/

• containerized software will always run the same, regardless of the environment

• Containers isolate software from its surroundings

E.g.: differences between development and staging environments helps reduce conflicts between teams running different software on the same infrastructure.

Why isolation ?

Practical Example - node-oracledb

After the setup of Oracle DB, various PATH variables (eg: OCI_LIB_DIR) ...

If you have Python 3.5 installed, you can't install this package:

https://github.com/oracle/node-oracledb

npm install

         node-gyp

                gyp

Various solutions:

• dangerous: https://github.com/oracle/node-oracledb/issues/18

cleanest:

Our upstream dependency gyp is Python 2 only, and as it's now EoL (Google won't be maintaining it) it's unlikely that it will be updated to support Python 3.

source

npm config set python python2.7 && npm install

With containers, typically many services (each represented as a single container) comprise an application. Applications are now able to be deconstructed into much smaller components which fundamentally changes the way they are managed in production.

Modularization

https://blog.docker.com/2016/03/containers-are-not-vms/

Case Study - Docker Compose

https://blog.docker.com/2016/03/containers-are-not-vms/

Docker promotes the idea of breaking an app into multiple services and building them based on a configuration file.

Case Study - Travis CI

DEMO

Applications

Docker demo

https://www.katacoda.com/xr86/scenarios/docker-primer

https://www.katacoda.com/courses/docker

Docker installation

https://www.docker.com/get-docker

https://store.docker.com/editions/community/docker-ce-server-ubuntu?tab=description

https://store.docker.com/editions/community/docker-ce-desktop-windows?tab=description

note: you can't use this and VirtualBox on the same machine

For windows 10 (Pro/ Enterprise/ Education, minimum build: 10586) use:

For ubuntu use this:

Otherwise:

https://www.docker.com/products/docker-toolbox

Windows:

Docker Toolbox installation

After running DockerToolbox.exe

You should have this icon on your desktop

Run this shortcut, and you should see similar output

Windows:

Docker Toolbox installation

If boot2docker has been succesful and you have approved the creation of the network adapters

You should now have this VM in VirtualBox

All set !

Windows:

Docker Toolbox installation

You may need to configure port forwarding, besides

(if you intend to deploy web apps on Windows)

EXPOSE <port> 

Linux (Ubuntu):

Docker CE/older installation

This is new(er):

https://store.docker.com/editions/community/docker-ce-server-ubuntu?tab=description

This is older:

https://www.digitalocean.com/community/tutorials/how-to-install-and-use-docker-on-ubuntu-16-04

In this context, the first option is good

Obs: Try Digital Ocean for devops/linux tutorials.

Linux (Ubuntu):

Docker CE/older installation

Add apt-repo for the install location

Install it ...

Linux (Ubuntu):

Docker CE/older installation

Check if the command works

Check a (random) docker image

Linux (Ubuntu):

Docker CE/older installation

Don't forget about sudo.

Alternatives:

https://askubuntu.com/questions/477551/how-can-i-use-docker-without-sudo

https://www.digitalocean.com/community/tutorials/how-to-install-and-use-docker-on-ubuntu-16-04

Orchestration

Part 2

Orchestration

Kubernetes (k8s) is:

• portable: public, private, hybrid, multi-cloud
• extensible: modular, pluggable, hookable, composable
• self-healing: auto-placement, auto-restart, auto-replication, auto-scaling

Orchestration

Orchestration concepts

The Kubernetes master is responsible for maintaining the desired state for your cluster. When you interact with Kubernetes, such as by using the kubectl command-line interface, you’re communicating with your cluster’s Kubernetes master.

The nodes in a cluster are the machines (VMs, physical servers, etc) that run your applications and cloud workflows. The Kubernetes master controls each node; you’ll rarely interact with nodes directly.

A pod is a Kubernetes abstraction that represents a group of one or more application containers (such as Docker or rkt), and some shared resources for those containers.

https://kubernetes.io/docs/concepts/

Pods vs Nodes

https://kubernetes.io/docs/concepts/

Orchestration concepts

A ReplicationController ensures that a specified number of pod "replicas" are running at any one time. In other words, a ReplicationController makes sure that a pod or group of pods are always up and available. If there are too many pods, it will kill some. If there are too few, the ReplicationController will start more.

The kubelet is the primary “node agent” that runs on each node.

Useful commands

kubectl cluster-info (~ docker ps ?)

check with: minikube status

minikube ip
minikube logs

minikube dashboard
minikube config

minikube <start | stop> (~ docker-machine start)

Usecase: Flexible, modular, scalable apps

Usecase: Container orchestration

for cloud providers

https://cloud.google.com/container-engine/docs/

Kubernetes demo

broken: https://www.katacoda.com/xr86/scenarios/kubernetes-primer​

https://www.katacoda.com/courses/kubernetes/launch-cluster

Windows:

Kubernetes installation

Full tutorial: https://rominirani.com/tutorial-getting-started-with-kubernetes-on-your-windows-laptop-with-minikube-3269b54a226

  Download:

   kubectl: http://storage.googleapis.com/kubernetes-release/release/v1.4.0/bin/windows/amd64/kubectl.exe

move to C:/, and add to PATH

   minikube:

https://github.com/kubernetes/minikube/releases/download/v0.17.1/minikube-installer.exe

add to PATH (apparently)

Windows:

Kubernetes installation

Check if the following commands work: 

kubectl version

minikube version

Obs: Logs (and metadata) now stored in:

%HOMEPATH%\.minikube

Windows:

Kubernetes minikube run

Start a new cluster:

minikube start --kubernetes-version="v1.4.0" 
               --vm-driver="virtualbox" 
               --show-libmachine-logs --alsologtostderr

You should see yet another VM in VirtualBox: 

 careful with enters, they will be ignored !

Windows:

Kubernetes minikube run

http://localhost:9090/api/v1/proxy/namespaces/kube-system/services/kubernetes-dashboard/#/admin?namespace=default

kubectl proxy --address="localhost" --port=9090

Serve admin dashboard from VM:

Linux (Ubuntu):

Kubernetes installation

ubuntu 14.04 (trusty):

sudo apt-get update
sudo apt-get install snapd
sudo groupadd lxd && sudo usermod -a -G lxd $USER
sudo reboot
sudo snap install conjure-up --classic
conjure-up kubernetes

sudo snap install conjure-up --classic
conjure-up kubernetes

ubuntu 16.04 (xenial):

more here: http://conjure-up.io/docs/en/users/#install-trusty-caveat