Docker for developers
#drupalday2015

Paolo Mainardi (@paolomainardi)
● CTO @sparkfabrik
● Drupal developer
● Docker enthusiast (dropdock.io, dockerhub@paolomainardi)
● Twin of @stefanomainardi
● Linux and open source lover (ildn.net)

Let’s start with
questions

● You read the online tutorial
● You installed docker locally
● You are using for development
● You are using on production
Raise your hands if

Outlines
● What is Docker and why it is important to know it.
● What a container is and how to use it.
● Developing PHP applications using Docker.
● Tips and tricks on real world usage.

● To make your local development and build workflow faster, more efficient, and
more lightweight.
○ If it works on my machine, it will work in production
○ No more dependency hell, different versions of PHP with their own
libraries, Mysql or Mariadb, Redis or Memcache, Sass or Less
compilers, NPM etc.etc.
○ Consistent development environment, same operating system, same
libraries, no matter the host operating system you are running.
○ Easy way to replicate production environment.
○ Concentrate on code, instead to (re)build the infrastructure your
application needs.
Ok, what can I use Docker for ?

What is Docker?

What is Docker ?
“Docker allows you to package an
application with all of its dependencies
into a standardized unit for software
development.”
https://www.docker.com/what-docker

How it is made Docker ?
● It relies on standard linux kernel features only (cgroups, namespaces,
capabilities ecc.)
● Static compiled binary based on golang, no extra moving parts.
● It natively runs on every linux distro and on mac/windows too thanks to
boot2docker vm. (https://www.docker.com/docker-toolbox)
● Fast and lightweight, no added overhead.
● Security by process isolation.
● Open container initiative also baked by Docker inc. (https://www.
opencontainers.org)

Virtual machines Containers
Docker is not virtualization

What is a container ?

What is a container ?
● It is a linux process.
● It sits on top of the base docker image
(usually an operating system image).
● It has its own network interface.
● It has its own process namespace.

Demo time

Docker is a platform
Docker is an open source platform to build, ship and run any app, anywhere.
● Build: Package your application in a container.
● Ship: Move that container from one host to another.
● Run: Execute your application.
● Any app: that runs on Linux (recently native Windows support)
● Anywhere: Local, remote, cloud, VM, RaspberryPI ecc. any platform capable
to run the docker engine.

Build: Dockerfiles
A “Dockerfile” is a text document that contains all the
commands to assemble a docker image in a programmatic
and reproducible way.

Build: Dockerfiles
FROM ubuntu:14.04
RUN apt-get update && apt-get install -y nginx
RUN echo 'Hi, I am in your container'
>/usr/share/nginx/html/index.html
CMD nginx -g "daemon off;"
EXPOSE 80
$ docker build -t paolomainardi/dday15web .
$ docker run -d -P paolomainardi/dday15web

BUILD DEMO

Build: What we learned
● It allows to create a docker image in
a programmatic and reproducible
way.
● Each build step gets cached (thanks
to overlaid filesystem)
● Re-run the build allows to skip slow
steps (ex: apt-get install)

Ship

Ship: Dockerhub
● git pull
● git push

Ship: Dockerhub
● git docker pull image from the registry
● git docker push image to the registry
http://hub.docker.com

SHIP TO DOCKERHUB DEMO

Ship: What we learned
● It mimics the git workflow.
● Images are self-contained, independent from the host.
● Exactly the same behaviour, on any environment.
● To easily replicate and share the environment your application expects.
● No more “it worked on my machine” excuse.

Run
docker run is-lightning-fast

RUN DEMO

Run: What we learned
● Execution is fast and lightweight.
● There is no overhead, they are just normal OS running processes.
● Containers are isolated.

Any app, anywhere
● If it works on Linux, it works on Docker.
● Not just for command-line apps
○ Chrome-in-docker
○ Firefox-in-docker
○ VPN-in-docker
○ etc…follow this repo to see crazy things: https://github.com/jfrazelle/dockerfiles
● Every linux host that run Linux 3.8+ x86_64 kernel

Developing PHP applications using Docker

Developing PHP applications using Docker

Developing PHP applications using Docker

Docker Compose to rule them all

Docker compose
● Describe your stack in one file docker-compose.yml
● Run your stack with a command docker-compose up

front:
image: drupal:7.41
volumes:
- ./sites/all/modules:/var/www/html/sites/all/modules
ports:
- "8080:80"
links:
- mariadb:mariadb
mariadb:
image: mariadb:10
ports:
- "3306:3306"
environment:
- MYSQL_ROOT_PASSWORD=root
- MYSQL_DATABASE=drupal
memcached:
image: memcached:1.4.25
ports:
- "1211:1211"
solr:
image: sparkfabrik/drupal-drupal-solr
ports:
- "8983:8983"
docker-compose-yml

DOCKER COMPOSE DEMO

The Docker ecosystem
When talk about Docker, we talk about an ecosystem of tools.
● Docker engine: Client and server daemon to build, ship and run containers.
● Docker hub: The official Docker image registry.
● Docker compose: Tool to orchestrate multi-container applications.
● Docker machine: Automated Docker hosts provisioning.
● Docker swarm: Host clustering and container scheduling.
Much more than this, check it out: https://www.docker.com/products/overview