Introduction to Docker

Amjith Ramanujam (New Relic) (@amjithr)

Typical Stack

• Django
• Apache/gunicorn
• Celery
• Redis/DB

Deployment environment doesn't always match dev environment...

What is Docker?

• DotCloud -> Docker Inc
• Started in January 2013
• Written in Go
• Similar to chroot, BSD jails, Solaris Zones... a little sandbox
• Uses Linux Containers (in kernel for ~5 years)
• AUFS
  • Union file system
  • Copy on write
• Git-like versioning
• REST API

Why?

• Lightwieght
• isolated instances
• faster than VMs
  • startup in < 1s

Setup

• docs.docker.io
• OS X: boot2docker (~25 MB VM) + docker client

Demo Commands

$ docker images
    $ docker run
    $ docker run -d ... # run in daemon mode
    $ docker commit
    $ docker push
    $ docker run -p ...  # bind port

Dockerfile

Fortunate Cow

    FROM base
    ENV TEST_ENV true
    ADD test_file /
    RUN apt-get update
    RUN apt-get install -y fortune cowsay
    CMD fortune | cowsay