Introduction to Docker

Containerization is the new virtualization

who

engineer and operations chapopen source chapfunny accent

(photo by Jennie Rainsford)

other mattersauthor

http://www.jamesturnbull.nethack-n-slash developer

https://github.com/jamtur01pontification

http://www.kartar.net

The Docker Book

www.dockerbook.com

Who are youfolks?

So what is Docker?Container virtualizationBuild, pack, ship and run applications as containersBuild once, run in many placesIsolated and content agnostic

Some history

So why should I care?Easy (and lightweight!) way to model realityDevs care about their app, Ops cares about the containersGolden images without the overhead

Why developers care...A clean, safe, hygienic and portable runtime environmentNo worries about missing dependencies, packages and other painpointsRun each app in its own isolated container, so you can run variousversions of libraries and other dependenciesAutomate testing, integration, packagingReduce/eliminate concerns about compatibility on different platforms

Why operations care...Make the entire lifecycle more efficient, consistent, and repeatableIncrease the quality of code produced by developersEliminate inconsistencies between development, test, and productionenvironmentsSupport segregation of dutiesSignificantly improves the speed and reliability of continuousdeployment and integration

So why not VMs or Cloud?Speed of deploymentPortabilitySize aka cached layering FTWDensity & PerformanceCost

Technology StackRuns (for now) on most Linux distroscgroups and namespacingDevice Mapper or AUFS or vfs or <pluggable in future>lxc or <pluggable in future>

Technology Stack

Docker BasicsImage

ContainerRegistry

Building Docker images with aDockerfile

FROM ubuntu MAINTAINER James Turnbull "james@example.com" RUN apt-get install -y apache2 ENV APACHE_RUN_USER www-data ENV APACHE_RUN_GROUP www-data ENV APACHE_LOG_DIR /var/log/apache2 EXPOSE 80 ENTRYPOINT ["/usr/sbin/apache2"] CMD ["-D", "FOREGROUND"]

Building the image$ sudo docker build -t="jamtur01/apache2" .

Pushing the image$ sudo docker push jamtur01/apache2

Running the container$ sudo docker run -d -p 80 -v /var/www/myapp jamtur01/apache2

Questions?