Docker allows for isolation of applications into lightweight containers that can be linked together and share resources. Containers are run from images that act as templates containing the files, configuration, and dependencies for an application. Images are built from Dockerfiles that define the build process and layers, and can be pulled from or pushed to a registry for distribution. Docker uses a client-server model with daemons managing containers on each host.

1. DOCKER
An introduction
Matthias Noback
@matthiasnoback
info@matthiasnoback.nl

2. CONTAINERS
"Just" processes, connected through the network
Your application
MySQL
Varnish
Memcache
Redis
HAProxy

3. CONTAINERS
Are about isolation
Processes
Files
Networking
Resources
Users

4. DOCKER
A set of CLI scripts
docker build
docker run
docker volume
docker network
...

5. localhost
DOCKER
A daemon and a client
Docker
daemon
client
container container container

6. some-other-machine
DOCKER
A daemon and a client
Docker
daemon
client
container container container

7. IMAGES
Container blueprints
Files
Exposed ports
Volumes

8. IMAGES
Pull or build
Image
registry
image
Docker-
file
image
pull from use to build

9. IMAGE REGISTRY
hub.docker.com

10. IMAGE REGISTRY
Push your own images
Image
registry
push to
Docker-
file
image
use to build

11. CONTAINERS
Linked through
Networks

12. CONTAINERS
Configured through
Build process
Environment variables
Volume mounts

13. ASSIGNMENTS/
ALL.MD
Playing with docker and Dockerfiles
https://github.com/matthiasnoback/docker-workshop/

14. EXPOSE VS PUBLISH
A port is exposed by the image itself
Publishing it makes it accessible to the bridge network (possible conflicts)
You can map ports: [host port]:[container port]

15. DOCKERFILE
Describes the build process of a container image
FROM php:7.1-apache
COPY web/ /var/www/html/
RUN pecl install redis
RUN docker-php-ext-enable redis
Cached filesystem layers!

16. DOCKERFILE
Optimized build
FROM php:7.1-apache
RUN pecl install redis
docker-php-ext-enable redis
COPY web/ /var/www/html/

17. BUILD CONTEXT
Files available while building the image
COPY web/ /var/www/html/

18. LOGGING
To stdout/stderr
No file rotation needed
You could look into logspout/Logstash/Kibana
There are also nice services for this

19. COPYING VS VOLUME MOUNTING
When to use what
Mount a volume while developing
Use COPY for creating the build artifact

20. READ-ONLY LAYERS
With a writeable layer on top
Stateful vs immutable

21. IMMUTABLE FILE SYSTEMS
How to store data on disk?
bind-mount volume
named volume ("volumes from")
fast/cache volume: tmpfs

22. CONTAINERS
Advantages
Self-contained ;)
Designed to be immutable (and predictable)
Infrastructure as code
Configuration has not been abstracted
Provisioning new servers is easy