Date: 2016-Nov-03
Presentation by: Joan Fuster
Meetup: Arduino Introduction
Introduction to
Docker
Alicante Tech Meetup
1
Who am I?
–
Joan Fuster
SysOps Engineer @ Ticketbis
jfusterm @ Github
joan.fuster@gmail.com
2
Agenda
– Introduction
– Docker Architecture
– Conclusions
There will be demos down the road 🙂
3
What we are going to learn?
–
What is Docker
What is a container
What problem does it solve
Why containers and microservices are
so popular right now
– Container vs VMs
– Docker architecture
– Typical Docker uses
4
Introduction
5
What is the problem here?
6
What is Docker?
“Platform to develop,
ship and run
applications into
containers”
7
What is a container?
– A full isolated runtime environment
– That environment includes everything
you need for your app:
– Filesystem
– Runtime
– Code
– Libraries
– It is not a mini-VM, it is just a
process
8
9
Why is it important?
–
Portability
No more dependency hell
No more dev/stage/prod problems
Idempotent
Easy to scale
More control for Devs
Less headaches for Ops
Redefines how applications are
deployed (faster)
10
Containers vs Virtual Machines
Source: Docker
11
Containers vs Virtual Machines
Containers
–
Process
MB
ms to boot
Higher density
VMs
–
Full OS
GB
Minutes to boot
Fewer density
12
Rise of the Microservices
Source: Docker
13
Docker
Architecture
14
Docker underlying technology
– Linux kernel ≥ 3.10 (recommended ≥ 4.0)
– cgroups (resource allocation)
– namespaces (isolation)
– unionFS (copy-on-write strategy)
– seccomp (system calls)
– capabilities (privileges)
– selinux/apparmor (security)
– Iptables (networking)
15
Docker components
–
Images
Containers
Registries
Services (≥ Docker Engine v1.12)
16
Docker images
– Build component of Docker
– Container’s base (think of a template)
– Uses UnionFS (implements a union mount
for other file systems)
– Composed of multiple layers
– A layer is a difference in the
filesystem
– Created from Dockerfiles (mainly)
17
Image layers
Source: Docker
18
Image layers
Source: Digital Ocean
19
Container layers
Source: Docker
20
Docker storage drivers
– Responsible for
– Docker can only
– Each driver has
implementation,
managing the layers
run one storage driver
a different
so perform differently
21
Supported storage drivers
–
OverlayFS
AUFS
Devicemapper
BTRFS
ZFS
22
Dockerfiles
–
Instructions to build the image
Uses a DSL (Domain Specific Language)
Automate the build
Instructions executed sequentially
Can be put under version control (Git)
Repeatable
23
Dockerfiles
FROM debian:jessie
RUN apt-get install -y emacs
RUN apt-get install -y apache2
$ docker build -t my-image:test .
24
Dockerfile main instructions
–
FROM (sets the base image)
ENV (sets environment variables)
RUN (execute commands)
COPY (copies files to the image)
EXPOSE (open ports at runtime)
ENTRYPOINT (defines the executable)
CMD (provide defaults for a container
and params to the entrypoint)
25
Dockerfile example – Good
FROM ubuntu:16.04
RUN apt-get update
RUN apt-get install -y nginx
COPY index.html /var/www/html/
EXPOSE 80
ENTRYPOINT [“/usr/sbin/nginx”,”-g”,”daemon
off;”]
26
Dockerfile example – Better
FROM ubuntu:16.04
RUN apt-get update && \
apt-get install -y nginx && \
rm -rf /var/lib/apt/lists/*
COPY index.html /var/www/html/
EXPOSE 80
ENTRYPOINT [“/usr/sbin/nginx”,”-g”,”daemon
off;”]
27
Base images
– The base image on which the
instructions will be executed
– Different flavours
– Each image has different sizes
28
Base images examples
–
centos:7 (196.5MB)
ubuntu:16.04 (127.2MB)
debian:jessie (123MB)
opensuse:latest (95.76MB)
alpine:3.4 (4.8MB)
29
Dockerfile example – Best
FROM alpine:3.4
RUN apk –no-cache add nginx && \
mkdir /run/nginx
COPY index.html /var/lib/nginx/html
EXPOSE 80
ENTRYPOINT [“/usr/sbin/nginx”,”-g”,”daemon
off;”]
30
Docker containers
–
Run component of Docker
Containers are built from a Docker image
Execution environment
Can contain one (microservices) or more
processes
– A docker container exits when its main
process finishes
31
Docker registries
– Distribution component of Docker
– Service where the Docker images are
stored
– Docker Registry / Trusted Registry
– Docker Hub
– Quay.io
– AWS EC2 Container Registry (ECR)
32
Docker services
– Scalability component of Docker
– Basic unit in a Docker Swarm
– Desired state of your application
33
Docker architecture
34
Docker Tools
–
Docker
Docker
Docker
Docker
Docker
Docker
Docker
Engine
Hub
Machine
Compose
Registry
Swarm
Cloud
35
Docker Engine
– Container runtime
– Available for Linux, Mac & Windows
– 3 major components:
– Daemon
– REST API
– CLI
36
Docker Engine
Source: Docker
37
Some Docker Engine commands
$
$
$
$
$
$
$
$
docker
docker
docker
docker
docker
docker
docker
docker
info
version
run
build
ps
images
start
stop
$
$
$
$
$
$
$
$
docker
docker
docker
docker
docker
docker
docker
docker
restart
rm
rmi
port
inspect
exec
tag
attach
38
$ docker run hello-world
39
$ docker run -it ubuntu bash
–
i: Attach container’s STDIN
t: Allocate a pseudo-TTY (aka terminal)
ubuntu: Ubuntu image
bash: Command to run in the container
40
$ docker run -d –name nginx
-p 80:80 nginx
41
Docker Hub
–
Docker Registry cloud service
Public and private repositories
Official images are stored in Docker Hub
Automated build triggered by changes
Webhooks
Github and Bitbucket integration
42
Docker Machine
– Create Docker hosts on:
– Local computer
– Data Center
– Cloud Provider
– Typically used to provision Docker
on Windows and Mac
43
Docker Compose
– Used to define and run multi-container
applications
– Defined in a YAML file
(docker-compose.yml)
– Great for testing environments
44
Docker Compose
version: ‘2’
services:
app:
image: php
ports:
– “80:80”
– “443:443”
volumes:
– code:/var/www/html
links:
– mysql
mysql:
image: mysql:5.7
ports:
– “3306:3306”
volumes:
code: {}
45
Docker Registry
– Docker images storage
– Used to store Docker images in-house
– Commercially supported with Trusted
Registry
46
Docker Swarm
– Docker clustering solution
– Failover and high availability
containers
– Since v1.12 integrated in Docker Engine
– Built-in orchestration, service
discovery and load balancer
– Multi-host networking
– Declarative service model
47
Docker Swarm Nodes
Source: Docker
48
Docker Swarm Services
Source: Docker
49
Docker Cloud
– Cloud platform to manage and deploy
Docker containers
– Integrates all the Docker tools
– CaaS (Container as a Service)
50
Conclusions
51
Docker use cases
–
Legacy applications
CI/CD
Sandboxes
Microservices
Immutable infrastructure
Server consolidation
52
Challenges
–
Monitoring
Networking
Data persistence
Service discovery
Orchestration
– All together…
53
Container OS
–
CoreOS
RancherOS
Atomic
Snappy
Mesosphere DCOS
PhotonOS
54
That’s all folks!
Q&A
Thank you 🙂
55
