Transcript
Introduction to Docker
@endhrk
Agenda
● What Is Docker● How To Use Docker
– How Do I Install Docker
– How Do I Use Docker
– How Do I Build containers
– How Do I Terminate
● Important Docker terms● Consisting Of Docker Engine
– Lightweight
– Portable
– Packaging
What Is Docker
● Open platform● For developers and system administrators● To build, ship ,run applications
How To Use Docker
● Install● Use● Build● Delete
How Do I Install Docker
*may not be the latest Docker release
**Install for Ubuntu 14.04
$ sudo apt-get -y install docker.io$ sudo ln -sf /usr/bin/docker.io /usr/local/bin/docker$ sudo gpasswd -a $USER docker
How Do I Use Docker
$ sudo start docker.io$ docker run -i -t ubuntu /bin/bashroot@0f0bd22ce93e:/#
How Do I Build Containers
● DockerfileFROM ubuntu:14.04RUN apt-get -y install apache2EXPOSE 80CMD [“/usr/sbin/apache2ctl”, “-D”, “FOREGROUND”]
$ docker build -t apache .$ docker run -d -P apachef254fc1aa31909783a26fb14f80d75ba128762b605604f95ef9a146de0ee46ed
How Do I Terminate
● Stop container
● Remove container
● Remove all images●
$ docker stop f254fc1aa319
$ docker rmi `docker images -q`
$ docker rm f254fc1aa319
Important Docker Terms● Docker image
– Is Read-only template● ex. contains an Ubuntu with Apache and applications
– Is used to create Docker container
– Provides simple way for delivery
● Docker registry– Holds images
– Provides simple way to upload and download images
– Has public and private● Public is called Docker Hub● Private Docker registry is provided by docker image at Docker Hub.
● Docker container– Is an isolated and secure application platform
– Is created from a Docker image
– Can be run, started, stopped, moved, deleted
Consisting Of Docker Engine
● Lightweight● Portable● Packaging
Consisting Of Docker Engine
● Lightweight● Portable● Packaging
Why Is Docker Lightweight
● Container virtualization● Union file system
Why Is Docker Lightweight
● Container virtualization● Union file system
What Is Container Virtualization
● Virtualization technology– Hardware virtualization (ex. VMware, Hyper-v)
– Container virtualization (ex. Docker, OpenVZ)
What Are Difference Between Technologies
Hardware virtualization Container virtualization
What is virtualized
Virtualized hardware environment Virtualized OS environment
What can be put on Host
Different OS Different Lib/Bin (kernel is shared)
What is launched
Launch OS Launch process
How to access I/O
Via Virtualized hardware Use directly limited resources
What Are Stacks Difference Between Technologies
Hardware
Hypervisor
Bin/Libs
MW MW MW
App App App
KernelBin/LibsKernel
Bin/LibsKernel
VirtualHardware
VirtualHardware
VirtualHardware
HardwareLinux kernel
Bin/Libs
Docker daemon MW MW
App App
Bin/Libs Bin/Libs
Hardware virtualization Container virtualization
How Much Are Their Performance Difference
CPU Memory fileio0 sec
5 sec
10 sec
15 sec
20 sec
25 sec
30 sec
35 sec
physical
docker
virtualbox
* This benchmark was measured using sysbench
Components ForContainer Virtualization
● Isolation– Identify a set of processes
– Isolate resources
– Don't recognize each other processes
● Resource control– Limit the resources used
* resource = process id, memory, cpu, disk space, network
How To RealizeContainer Virtualization
● Using kernel feature● Isolation via namespace
– PID namespace
– Network namespace
– UTS namespace (hostname etc.)
– IPC namespace
– Mount namespace
● Resource control via cgroups– Resource limiting
– Prioritization process
– Accounting using resources
– Control groups
What Is Meant By Lightweight For Container
● Container virtualization– Launch faster
● launch only process. Kernel was already booted.
– Use resources efficiently● Kernel and memory are shared
– Run process faster● There is no overhead like hardware virtualization
Why Is Docker Lightweight
● Container virtualization● Union file system
What Is Union File System
● Union file system is– Several filesystems to be mounted, appearing to be
one filesystem
● Docker uses aufs– You can choose other option (ex. devicemapper
How Does Aufs Work
1.Mount a base image as read-only
2.Add read-write file system over read-only file system
3.Change some files and directories to top as read-write file system
4.It is committed
5.Save incremental files and directories in new image
6.Mount the image as read-only and add read-write file system on top
How Does Aufs Work
What Is Meant By Lightweight For Union File System
Bin/Libs
MW
App
Image
Bin/Libs
MW
App
Container1
shared
MW
App
Container2
● Owing to use of union file system– Not changed files are shared for each containers
– Storage and memory spaces are saved
– Faster deployment of containers
shared
MW
App
Container3
shared
shared
App
Container4
Consisting Of Docker Engine
● Lightweight● Portable● Packaging
Why Is Docker Portable
● Run anywhere● Simple way to take image to another
environment● Copy Incremental files only
Which Environment Can I Use
● Run anywhere– Any OS?
● ex. Linux, ?Mac OSX?, ?Windows?
– Any Cloud● ex. Google Cloud Platform, Amazon Web Services, SoftLayer
– Any Physical Machine● ex. Your PC, Server for production
*You have to use Docker on Virtualbox if you use Mac OSX or Windows
How Can I Take the Image
● Simple way to take image to another environment– Docker Hub (like GitHub)
● Can set tag (version control)● Easy to push image● Easy to pull image● Allow to access from anyone
– Private registry● Can limit access person who is not allowed● Basic features are same as Docker Hub
What Does Docker Copy
Bin/Libs
MW
App
Bin/Libs
MW
App Diff
Image
Bin/Libs
MW
App
Container
Update
Container
Commit
Diff
Image
Run
Run
Bin/Libs
MW
App Diff
Container● Save only changed files● Push or pull just small increment files
What Is Meant By Portable
● Run anywhere● Simple way to take image to another
environment● Copy Incremental files only
Consisting Of Docker Engine
● Lightweight● Portable● Packaging
What Is Packaged In Docker Image
● Docker image contains– Application
– Middleware required by Application
– Basic programs (like a OS)
– Settings● Application, Middleware, OS(Disk, Network)
● All of things for running Application
What Is Meant By Packaging
● Image contains all of things for running application
● Packaging realize– Portable and reliable application deployments
– Rapid and efficient application delivery
– Simplified application runtime environment
– Coding explicit knowledge
Review
● How to use Docker● Important docker terms● Consisting of Docker Engine
– Lightweight
– Portable
– Packaging
Thanks
top related