Containerizing Your Dev Environment

Containerizing Your Dev Environment

Laura Frank

rheinwein

@rhein_wein

rheinwein/hello-world-container-demo

Containerization: what even is it?

Setting up a dev environment

Docker ecosystem nuts and bolts

A tool for managing containers

• Managing code that goes in them • Executing code inside of them

• Run in a self-contained execution environment • Share the kernel of host system • Are isolated from other containers • Have fast boot times & low overhead

Containers

A container is a virtualization layer — sort of like a VM — but with some fundamental differences

hardware

host OS

hypervisor

$ guest OS

libraries

app 1

$ guest OS $ guest OS

libraries

app 2

libraries

app 1

libraries

app 1

libraries

app 2

hardware

host OS

libraries

app 1

hardware

host OS

container runtime engine

libraries libraries

app 1 app 1 app 2

Containers have slightly more complexity

but

They reduce the amount of time/space resources needed to run your application

• It’s fast! • It’s cheap! • It’s portable! • It’s safe!

Benefits of Containerization

A Bird’s Eye View of Docker


• Managing code that goes in them • Executing code inside of them

Engine Hub

docker.com

registry.hub.docker.com

Interacting with the Registry

• Push and pull —just like GitHub • Two types of images

• Services • Project base images

Private Registries

• Get setup image from Docker Registry • Can have authentication • Push and pull just like with Docker Hub


• Managing code that goes in them

• Executing code inside of them

hardware

host OS

container runtime engine

libraries libraries

app 1 app 1 app 2

• docker run my_image • docker pull your_image • docker images • docker ps

Docker CLI

• Docker daemon runs with each container

• Daemon exposes API with RESTful endpoints

• Using CLI == using API, just abstracted • You could build your own tooling

Docker API

Setting Up Your Dev Environment with Docker

Objectives

• Put code in container • Run the code inside the container • See application in web browser

• A computer* • Code to run • Coffee (if you’d like)

Things you need

Installing Docker

Anything else? You need to use a lightweight VM.

Pro Tip: Boot2Docker (OSX and Windows)

Linux? Install Docker with official packages.

A Computer

• Linked folders • Copied files • Port forwarding

Handling Abstraction

Code may seem out of reach, but can be managed using

An image is controlled by a Dockerfiledocker build -t foo/bar .

docker pull foo/bar

Code to Run

All containers are based on images

Code to Run

• Static: all files and code are contained in image

• Dynamic: link folders to actively modify code (development only)

SEHR WICHTIG!

FROM centurylink/ruby-base:2.1.2

MAINTAINER Laura Frank <[email protected]>

EXPOSE 4567

RUN mkdir -p /usr/src/app ADD . /usr/src/app

WORKDIR /usr/src/app RUN bundle install

CMD “ruby hello_world.rb"

Dockerfile



EXPOSE 4567




Dockerfile

This copies code into the container

STATIC! Not for apps under active development

Great for dependencies and production applications



EXPOSE 4567




Dockerfile

This makes things happen to your code



EXPOSE 4567




Dockerfile

This makes the code happen


No need for version management, just use a different base image.

Base images are great!

Dockerfile

• Available on Docker Hub • Maintained by other people (laziness++) • Repositories includes instructions for

bootstrapping • Images can be base images or actually

run services

Official Images

The Easy Way: Boot2Docker

• Creates folder links for you • Obscures the separation between VM and

host • Super handy for quick, small projects • Not great for more complex systems

The Hard Way: Vagrant

• Manually create folder links • Choose your own OS • Must ssh into VM • Great for more customization

The Hard Way: Vagrant

config.vm.box_url = "http://storage.core-os.net/coreos/amd64-usr/alpha/coreos_production_vagrant.json"

config.vm.synced_folder "/Users/lfrank/CTL/panamax/panamax-api", "/var/panamax-api", id: "core", nfs: "true", mount_options: ['nolock,vers=3,udp']

Either Way• Remember to forward ports in order to

access app in a browser

-p host_port:container_port

(Sorry.)

…is kind of a pain.

Debugging in a Container

Use a remote debugger.


If you’re a Rubyist, use Pry

require ‘pry’

class Thing def some_method binding.pry #some brilliant broken code end end


Application Templating

• Use your own images, or images from the Docker Registry

• Specify config options beforehand (like port forwarding)

• Run applications with one or two simple commands

Standards tightly coupled with Docker

fig.sh

Dump requirements into fig.yml and run with fig up

Docker workflow tool

Itself a containerized application

panamax.io

Uses CoreOS, Fleet, and etcd for orchestration and service discovery

Templating language similar to fig

Supports remote deployments

panamax.io/get-panamax

--- name: Rails with PostgreSQL description: Rails with PostgreSQL

images: - category: Web Tier name: Rails source: rheinwein/rails:latest description: Rails App type: Default expose: [] ports: - host_port: '8080' container_port: '3000' links: - service: Database alias: DB_1 environment: [] volumes: []

–Johnny Appleseed

“Type a quote here.”

Additional Resources

Docker Hub: registry.hub.docker.com

Documentation: docs.docker.com

Boot2Docker: boot2docker.io

Panamax: panamax.io

CenturyLink Labs: centurylinklabs.com

Thanks!

Laura Frank

rheinwein

@rhein_wein

Containerizing Your Dev Environment

Technology

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