This is a simple presentation I held about Docker in the Linux User Group of my town.

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!