Docker enables software developers to package applications and all dependencies so they can run unchanged anywhere. It allows system administrators to simplify application deployment, easily scale resources up or down, and isolate processes. Docker uses Linux technologies like namespaces, control groups, layered filesystems, and LXC to virtualize operating systems and run containers. Users install Docker Engine, use Dockerfiles to build images from which containers are launched, and manage machines with Docker Machine.

1. From zero to
Docker
Giovanni Toraldo
@ LuccaLUG

2. Docker: what is it?
Enables software developers to:
● package an application
● with all dependencies
● runs it everywhere unchanged

3. Docker: what is it?
Enables system administrators to
● simplify application deployment
● ease scale-up & scale-down
● processes separation

4. Underlying technologies
● Linux namespaces
● Control Groups (cgroups)
● Layered filesystems
● LXC (now libcontainer)

6. Glossary
● Image: immutable snapshot of a container,
push/pull repository
● Container: an instance launched from an image
● Volume: persistent writable area of a container
● Registry: repository of images (versioned via
tags)
● Dockerfile: the descriptor from which an image
is built

7. How to install docker engine
● GNU/Linux
deb https://apt.dockerproject.org/repo ubuntu-trusty main
deb https://apt.dockerproject.org/repo debian-jessie main
pacman -S docker
● Windows / OSX
https://www.docker.com/products/docker-toolbox

9. Docker-machine
Machine manager (like Vagrant)
https://github.com/docker/machine
(Win/Mac: distributed in Docker toolkit)
● Launch VM somewhere
● Install Docker
● Generates and copy certificates
○ (password-less auth)
● Enable remote access via TCP

10. Docker-machine backends
Where nodes can run?
● Generic backend
○ existing hosts with ssh access
● Local machine (virtualization)
○ Virtualbox
○ VMware Fusion
● Cloud providers
○ Amazon
○ GCE
○ Rackspace
○ DigitalOcean
○ ...

11. Docker-machine bootstrap examples
$ docker-machine create --driver generic --generic-ip-address=<ip-address>
<nodename>
$ docker-machine create --driver virtualbox <nodename>
$ docker-machine create --driver digitalocean --digitalocean-access-token <token>
<nodename>
$ docker-machine create --driver amazonec2 --amazonec2-access-key <key> --
amazonec2-secret-key <secret> <nodename>
$ docker-machine create --driver kvm --kvm-cpu-count 2 --kvm-disk-size 20 --kvm-
memory 4096 <nodename>

12. Interaction with a Docker-machine node
$ docker-machine env default
export DOCKER_TLS_VERIFY="1"
export DOCKER_HOST="tcp://192.168.99.100:2376"
export DOCKER_CERT_PATH="/home/gionn/.docker/machine/machines/default"
export DOCKER_MACHINE_NAME="default"
# Run this command to configure your shell:
# eval "$(docker-machine env default)"
$ docker info
Kernel Version: 4.1.17-boot2docker
Operating System: Boot2Docker 1.10.0 (TCL 6.4.1); master : b09ed60 - Thu Feb 4
20:16:08 UTC 2016

13. Hello world
$ docker run -ti ubuntu:14.04 /bin/bash
● Live demo time

14. What happens under the hood?
● Pulls the ubuntu image from registry
● Creates a new container
○ Allocates a rw filesystem
○ Allocates a network interface (on a bridge)
○ Sets up network (IP address, dns..)
● Launch a process in the container
● Captures and provides application output
Container terminates when the process exit

15. Dockerfile (not the best example)

16. Standard workflow
Build & push:
● docker build -t gionn/nodejs-app:1.0.0 .
○ a tagged image is generated
● docker push gionn/nodejs-app:1.0.0
○ publish to repository
Pull & run:
● docker pull gionn/nodejs-app:1.0.0
○ fetch from repository
● docker run gionn/nodejs-app:1.0.0
○ run container from this image

17. Docker compose
Compose is a tool for defining and running multi-container
Docker applications using a file in YML format.
$ docker-compose up
Examples:
https://github.com/ClouDesire/docker-compose-library

18. Thanks!