Docker for Fun and Profit, Devoxx 2014

Docker for Fun and Profit
Carl Quinn
Java Posse, Riot Games
http://github.com/cquinn/devoxx14
#DV14 #Docker4Fun @cquinn

Schedule
➡About Docker
➡Getting Docker
➡Booting to Docker
➡The Docker Daemon
➡Images and Containers
➡Images, Layer by Layer
➡Simple Dockerized
Service
➡Containers and Networks
➡Containers and Volumes
➡Linking Containers
Together
➡Using cAdvisor
➡Basic Docker Clusters
➡Fleet
➡More: Mesos, Kubernetes

About Docker
What It Is

Containerization vs Virtualization

About Docker
Origins

Origins
• Google circa 2007
• Linux cgroups (control groups) (resource limits)
• Linux namespaces (resource isolation)
• Docker circa 2013
• Layered virtual filesystem
• One stop shop encapsulating many Linux kernel features

About Docker
Why It Is So Good

Sounds cool, but what’s the big deal?

Universal Deployable Artifact
• Complete: Everything the app needs is in the artifact.
• Small: The artifact is small enough to be easily managed.
• Immutable: The contents of the artifact can’t change.
• Universal: The artifact can run on any Linux host.
• Deployable: The artifact can actually be run directly, without
being unpacked or installed.

Image Sharing
• Universal Images are Easy to Share
• https://hub.docker.com/

Getting Docker

Home base
• https://docker.com/
• Current version: 1.3.1
• Requires 64-bit Linux

Docker Environment on Linux
• Ubuntu Trusty (14.4)
• CentOS 7
• CoreOS https://coreos.com/ 472.0.1
• Other Linux: RedHat, Fedora, Debian, Gentoo, etc
• Cloud: AWS, Rackspace, GCE, etc

Docker Environment on Mac
• boot2docker
• and/or: brew install docker
• Installs virtual box with a tiny Linux that runs Docker
• Docker cmdline client runs on Mac

Docker Environment on Windows
• boot2docker
• Installs virtual box with a tiny Linux that runs the Docker daemon
• May have to shell into the VM to work
• (I have no direct experience)

Booting to Docker
Mac Version

Client / daemon Comm
• Clear vs TLS
• Boot2docker now defaults to TLS
• Can switch to clear
• /var/lib/boot2docker/profile : DOCKER_TLS=no

Clear Comm
Daemon:
/usr/local/bin/docker -d -D -g /var/lib/docker
-H unix:// -H tcp://0.0.0.0:2375
Client
DOCKER_HOST=tcp://192.168.59.103:2375

TLS Comm
Daemon
/usr/local/bin/docker -d -D -g /var/lib/docker
-H unix:// -H tcp://0.0.0.0:2376
--tlsverify
--tlscacert=/var/lib/boot2docker/tls/ca.pem
--tlscert=/var/lib/boot2docker/tls/server.pem
--tlskey=/var/lib/boot2docker/tls/serverkey.pem
Client
DOCKER_HOST=tcp://192.168.59.103:2376
DOCKER_TLS_VERIFY=1
DOCKER_CERT_PATH=/Users/cquinn/.boot2docker/certs/

Boot2docker VM
• vboxnet2 is mapped to nested Linux VM
• My case: tcp://192.168.59.103

Poking around boot2docker
boot2docker init
boot2docker status
boot2docker version
boot2docker start
boot2docker suspend
boot2docker stop
boot2docker restart
boot2docker ssh
docker info
docker version

The Docker Daemon

Docker Client & Daemon

The Docker Daemon
• Use same binary as cmdline Client
• Runs on init or as needed
• Does all the work

The Docker Daemon
• Uses libcontainer to talk to Linux kernel
• Starts process group for container
• Creates namespaces for process group
• Creates cgroups for resource quotas
• Controls network access, port mapping
• Controls volume mounting

Docker Daemon REST API
• Docker daemon exposes an HTTP JSON over REST API
• See: https://docs.docker.com/reference/api/docker_remote_api/
• Version 1.15
• Normally this is over a local unix socket, but can go over tcp as
well.

Talk to the Docker Daemon
http http://192.168.59.103:2375/v1/_ping
http http://192.168.59.103:2375/v1/version
http http://192.168.59.103:2375/v1/info
http http://192.168.59.103:2375/images/json?all=0
http is HTTPie, a fancy curl
https://github.com/jakubroztocil/httpie

Images and Containers

Images, Registries and Containers
• Image is the package of bits (you might think of this as the
container, but that’s not exactly right)
• repository (think git repo)
• tag
• ID
• Registry is the repository of images
• Container is a running self-contained process group
• Dockerfile is the Makefile for Docker images

docker images
docker pull
docker inspect
docker tag
docker push

Images, Layer by Layer

Image Layers

Base Image Examples
• debian
• busybox
• ubuntu
• centos
• https://registry.hub.docker.co
m/_/debian/
m/_/busybox/
m/_/ubuntu/
m/_/centos/

docker history

Simple Dockerized Service
Example: ticktock

ticktock
• Very simple Go app that just writes to stdout

ticktock
…
func main() {
for i := 0; i < 10000; i++ {
if i%2 == 0 {
fmt.Printf("Tick %dn", i)
} else {
fmt.Printf("Tock %dn", i)
}
time.Sleep(1000 * time.Millisecond)
}
}

Build and run on Mac
make clean ticktock
./ticktock

Dockerize
FROM busybox:ubuntu-14.04
MAINTAINER cquinn
ADD ./bin/linux/amd64/ticktock /ticktock
CMD /ticktock

Dockerize
make docker_image
docker images
docker history
docker inspect

Demo

Containers and Networks
Example: webhellogo

const CounterFile = "/data/counter"
func main() {
os.Mkdir("/data", os.ModeDir|0755)
web.Get("/", func() string {
msg := fmt.Sprintf("Hello Go言語%d!”,
readUpdatedCounter()) // (Hello GoLanguage)
fmt.Println(msg)
return msg
})
web.Run(":8080")
}

func readUpdatedCounter() int {
store, _ := ioutil.ReadFile(CounterFile)
var i = 0
fmt.Sscanf(string(store), "%d", &i)
i++
store = []byte(fmt.Sprintf("%d", i))
ioutil.WriteFile(CounterFile, store, 0755)
return i
}

FROM busybox:ubuntu-14.04
MAINTAINER cquinn
ADD ./bin/linux/amd64/webhellogo /webhellogo
CMD /webhellogo

make docker_image

docker run -d -p 9090:8080
--name="webhellogo" cquinn/webhellogo

Containers and Volumes
Example: webhellogo

docker run -d -p 9090:8080
-v /home/docker:/data
--name="webhellogo" cquinn/webhellogo

Linking Containers Together
Example: figgy

Linked Containers

figgy app.py
from flask import Flask
from redis import Redis
import os
app = Flask(__name__)
redis = Redis(host="redis_1", port=6379)
@app.route('/')
def hello():
redis.incr('hits')
return 'Hello World! I have been seen %s times.' %
redis.get('hits')
if __name__ == "__main__":
app.run(host="0.0.0.0", debug=True)

FROM orchardup/python:2.7
ADD . /code
WORKDIR /code
RUN pip install -r requirements.txt

Fig
• Use Fig instead of lots’o bash
• http://www.fig.sh/
• https://github.com/docker/fig
• http://blog.docker.com/2014/08/getting-started-with-orchestration-
using-fig/

figgy’s Fig fig.yml
web:
build: .
command: python app.py
ports:
- "5000:5000"
volumes:
- .:/code
links:
- redis
redis:
image: orchardup/redis

Using cAdvisor
Example: cadvisor

cAdvisor
• https://github.com/google/cadvisor

Extra Credit
• Can also hookup InfluxDB + Grafana
• http://influxdb.com/
• http://grafana.org/
• Or use Heapster across a cluster
• https://github.com/GoogleCloudPlatform/heapster

Clusters of Dockers

Clustering with Docker
• Dockers are black boxes
• Config goes into args & env.
• Functional I/O is on network ports.
• System needs to Solve
• configuration delivery
• dynamic service addressing

Deploy
Service Addressing
Cluster
Docker
Configuration

Basic Docker Clusters
Example: cluster

docker

docker cloud-init
coreos:
units:
- name: docker-tcp.socket
command: start
content: |
[Unit]
Description=Docker Socket for the API
[Socket]
ListenStream=2375
Service=docker.service
BindIPv6Only=both
[Install]
WantedBy=sockets.target

docker cloud-init (cont)
- name: enable-docker-tcp.service
command: start
content: |
[Unit]
Description=Enable the Docker Socket for the API
[Service]
Type=oneshot
ExecStart=/usr/bin/systemctl enable docker-tcp.socket

Fleet
Example: fleet

fleet
• https://coreos.com/using-coreos/clustering/
• https://coreos.com/docs/launching-containers/
launching/launching-containers-fleet/

fleet cloud-init
coreos:
etcd:
# generate a new token for each unique cluster from
https://discovery.etcd.io/new
discovery:
https://discovery.etcd.io/b6efb8e37cfaafbabaeeca4392d74909
# multi-region and multi-cloud deployments need to use
$public_ipv4
addr: $private_ipv4:4001
peer-addr: $private_ipv4:7001
units:
- name: etcd.service
command: start
- name: fleet.service
command: start

./fleetctl --endpoint=http://10.97.129.5:4001 $@

myapp.service
[Unit]
Description=MyApp
After=docker.service
Requires=docker.service
[Service]
TimeoutStartSec=0
ExecStartPre=-/usr/bin/docker kill busybox1
ExecStartPre=-/usr/bin/docker rm busybox1
ExecStartPre=/usr/bin/docker pull busybox
ExecStart=/usr/bin/docker run --name busybox1 busybox /bin/sh -c
"while true; do echo Hello World; sleep 1; done"
ExecStop=/usr/bin/docker stop busybox1

More: Mesos, Kubernetes

Mesos
• http://mesos.apache.org/
• https://mesosphere.com/learn/

Kubernetes
• Googles next generation “lmctfy” for Docker
• https://github.com/GoogleCloudPlatform/kubernetes
• Available on GCE

Admiral
• Our Simple Cluster Manager

Admiral
Admiral
cmdline

Links & Credits
• Images from
• http://www.slideshare.net/dotCloud/docker-intro-november
• https://coreos.com/

Docker is the latest hotness in the deployment automation space, and opens a whole
new world of opportunities in how we bundle, deploy and manage our running apps.
Learn what Docker is all about and how to get started working with it.
During this university, you will learn how to get Docker installed and get started using it
to build and run your own containers. We'll take Docker apart and see how it works
under the hood. Then we'll zoom out and experiment with Fleet and Mesos –
interesting technologies built upon Docker for deploying containers to clusters of
machines. All the while, we'll talk about how this new technology is poised to radically
change how we think about deployment.

Docker for Fun and Profit, Devoxx 2014

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