Rafael Martins

rafael84@gmail.com

Jan, 2015

What's Docker?

$ docker --help

Usage: docker [OPTIONS] COMMAND [arg...]

A self-sufficient runtime for linux containers.

So... what's a

LINUX CONTAINER

again?

First things first

Virtual Machines

Virtual Machine

Server

guest os

}

host os

}

HYPERVISOR

Hypervisor

A piece of computer software, firmware or hardware that creates and runs virtual machines.

http://en.wikipedia.org/wiki/Hypervisor

Hypervisor Types

Server

Hypervisor (type 1)

Server

Host OS

Hypervisor (type 2)

Hyper-V
XenServer
KVM

VMware Fusion
Oracle VirtualBox
Parallels Desktop for Mac

So far so good?

Virtual Machines

Containers

VMs

Server

Host OS

Hypervisor (type 2)

Guest OS

Bins /
Libs

App

Server

Host OS

Bins / Libs

App

Containers

App

Guest OS

Bins /
Libs

App

Container Manager

VMs

Containers

Emulate virtual hardware
FAT in terms of system requirements
Need a Guest OS for each instance
Usually, Guest OS resources must be defined upfront (amount of RAM, for instance)
Are SLOW

Share Host OS resources
May share Libs / Bins
Ultra lightweight in terms of system requirements
Are FAST. Really, really FAST!

What's Docker?

$ docker --help

Usage: docker [OPTIONS] COMMAND [arg...]

A self-sufficient runtime for linux containers.

Server

Host OS

Bins / Libs

App

Docker Engine

App

CLI

Rest API

Dockerfiles

Container Manager

Docker

Registry

Docker

HUB (PaaS)

Docker Machine*

Docker Swarm*

~~FIG~~ Docker Compose*

Images

Docker Ecosystem

* http://blog.docker.com/2014/12/docker-announces-orchestration-for-multi-container-distributed-apps/

Images, Layers, Containers

Definition

Read-only or read-write file system

LAYER

Read-only LAYER
Can be a result of multiple (read-only) layers stacked on top of each other

IMAGE

Process launched based on an IMAGE
Add a read-write layer on top all read-only layers

CONTAINER

Base Image

bootfs

(bootloader, kernel)

rootfs

/dev, /proc, /bin, /etc, /lib, /usr, /tmp

{

Debian

Image

}

layer

}

Stacked Layers

bootfs

Kernel

Debian

Base Image

CentOS

Base Image

Apache:80

Image

Nginx:80

Image

Writable FS

{

App

}

App

Writable FS

So far so good?

First steps with Docker

host-os $ docker search ubuntu

Search for a pre-built image

NAME DESCRIPTION STARS OFFICIAL AUTOMATED

ubuntu Official Ubuntu base image 1208 [OK]

host-os $ docker pull ubuntu:latest

Download a pre-built image

host-os $ docker images

Listing available images

REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE

ubuntu latest 9bd07e480c5b 7 weeks ago 192.7 MB

host-os $ docker run -i -t ubuntu /bin/bash

Running an interactive shell

ubuntu $ _

host-os $ docker run -d ubuntu \

Starting a long-running worker process

> /bin/sh -c "while true; do echo Hello World; sleep 1; done"

fd2827f60bf56d00e0ef21e711df153e05585f27a382bdccaced3dd51921e232

host-os $ _

host-os $ docker ps

Listing containers

CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
fd2827f60bf5 ubuntu:latest "/bin/sh -c 'while t 9 minutes ago Up 8 minutes blue_sky

host-os $ docker ps -a

CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
fd2827f60bf5 ubuntu:latest "/bin/sh -c 'while t 9 minutes ago Up 8 minutes blue_sky

7f60ad3fabf5 ubuntu:latest "/bin/sh -c 'while t 9 minutes ago Exited (-1) 6s red_sea

Controlling containers

host-os $ docker stop blue_sky

STOP

host-os $ docker start blue_sky

START

host-os $ docker stop blue_sky

host-os $ docker rm blue_sky

REMOVE

Committing (saving) a container state

host-os $ docker commit blue_sky sky_img

host-os $ docker images

REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE

sky_img latest e480abcedc3b 5 seconds ago 192.7 MB

host-os $ docker --help

Complete Reference

attach
build
commit
cp
create
diff
events
exec

export
history
images
import
info
inspect
kill
load

login
logout
logs
port
pause
ps
pull
restart

rm
rmi
run
save
search
start
stop

...and more...

Dockerfiles

Docker can build images automatically by reading the instructions from a Dockerfile.

A Dockerfile is a text document that contains all the commands you would normally execute manually in order to build a Docker image.

By calling docker build from your terminal, you can have Docker build your image step by step, executing the instructions successively.

Sample Dockerfile

https://github.com/docker-library/java/blob/master/openjdk-8-jre/Dockerfile

FROM buildpack-deps:sid-curl

RUN apt-get update && apt-get install -y unzip \
    && rm -rf /var/lib/apt/lists/*

ENV JAVA_VERSION 8u40~b22
ENV JAVA_DEBIAN_VERSION 8u40~b22-2

ENV CA_CERTIFICATES_JAVA_VERSION 20140324

RUN apt-get update && apt-get install -y \
        openjdk-8-jre-headless="$JAVA_DEBIAN_VERSION" \
        ca-certificates-java="$CA_CERTIFICATES_JAVA_VERSION" \
    && rm -rf /var/lib/apt/lists/*

RUN /var/lib/dpkg/info/ca-certificates-java.postinst configure

Building an Image

host-os $ docker build -t openjdk-8-jre .

Uploading context 10.24 kB
Uploading context

Step 1 : FROM buildpack-deps:sid-curl
---> cbba202fe96b

Step 2 : RUN apt-get update && apt-get install -y unzip && rm -rf /var/lib/apt/lists/*
---> 51182097be13

...

Step 7 : RUN /var/lib/dpkg/info/ca-certificates-java.postinst configure

Successfully built 1a5ffc17324d

Demo

Questions ?

Thank You!

Docker

By Rafael L Martins

Docker

Introduction to Docker

Rafael L Martins

def me(): return " dev* "

What's Docker?

So... what's a

LINUX CONTAINER

again?

First things first

Virtual Machines

Virtual Machine

Hypervisor

Hypervisor Types

So far so good?

Virtual Machines

Containers

VMs

Containers

VMs

Containers

What's Docker?

Docker Ecosystem

Images, Layers, Containers

Definition

Base Image

Stacked Layers

So far so good?

First steps with Docker

Search for a pre-built image

Download a pre-built image

Listing available images

Running an interactive shell

Starting a long-running worker process

Listing containers

Controlling containers

STOP

START

REMOVE

Committing (saving) a container state

Complete Reference

Dockerfiles

Sample Dockerfile

Building an Image

Demo

Questions ?

Docker

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