Docker Basics
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This document discusses containers, virtual machines, and Docker. It provides an overview of containers and how they differ from virtual machines by sharing the host operating system kernel and making more efficient use of system resources. The document then covers Docker specifically, explaining that Docker uses containerization to package applications and dependencies into standardized units called containers. It also provides examples of Docker commands to build custom images and run containers.
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Docker Basics
- 1. App Container Docker Basics Eueung Mulyana http://eueung.github.io/docker-stuff/intro CodeLabs | Attribution-ShareAlike CC BY-SA 1 / 36
- 2. Outline VMs, Containers, Docker Getting Started - Docker Engine Custom Images Docker Compose 2 / 36
- 3. VMs, Containers & Docker Introduction 3 / 36
- 4. Virtual Machines Each virtual machine includes the application, the necessary binaries and libraries and an entire guest operating system - all of which may be tens of GBs in size. Containers (Docker) Containers include the application and all of its dependencies, but share the kernel with other containers. They run as an isolated process in userspace on the host operating system. They're also not tied to any speci c infrastructure. (Docker) Containers running on a single machine all share the same operating system kernel so they start instantly and make more e cient use of RAM. Images are constructed from layered lesystems so they can share common les, making disk usage and image downloads much more e cient. 4 / 36 Virtual Machines vs. Containers Containers have similar resource isolation and allocation bene ts as virtual machines but a di erent architectural approach allows them to be much more portable and e cient. Ref: docker.com
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- 6. LXC LXC owes its origin to the development of cgroups and namespaces in the Linux kernel to support lightweight virtualized OS environments (containers) and some early work by Daniel Lezcano and Serge Hallyn dating from 2009 at IBM. The LXC Project provides tools to manage containers, advanced networking and storage support and a wide choice of minimal container OS templates. It is currently led by a 2 member team, Stephane Graber and Serge Hallyn from Ubuntu. The LXC project is supported by Ubuntu. Docker Docker is a project by dotCloud now Docker Inc released in March 2013, initially based on the LXC project to build single application containers. Docker has now developed their own implementation libcontainer that uses kernel namespaces and cgroups directly. 6 / 36 Containers Container (lightweight process virtualization) technology is not new, mainstream support in the vanilla kernel however is, paving the way for widespread adoption (Linux Kernel 3.8 - released in February 2013 - cf. Rami Rosen). FreeBSD has Jails, Solaris has Zones and there are other (Linux) container technologies: OpenVZ, VServer, Google Containers, LXC/LXD, Docker, etc. Ref: Flockport
- 7. Both LXC and Docker are userland container managers that use kernel namespaces to provide end user containers. We also now have Systemd-Nspawn that does the same thing. The only di erence is LXC containers have an an init and can thus run multiple processes and Docker containers do not have an init and can only run single processes. 7 / 36 LXC vs. Docker Ref: Flockport
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- 9. 9 / 36 Docker Docker allows you to package an application with all of its dependencies into a standardized unit for software development. Docker containers wrap up a piece of software in a complete lesystem that contains everything it needs to run: code, runtime, system tools, system libraries - anything you can install on a server. This guarantees that it will always run the same, regardless of the environment it is running in. Docker containers run on any computer, on any infrastructure and in any cloud. Ref: docker.com
- 10. Containers isolate individual applications and use operating system resources that have been abstracted by Docker. Containers can be built by "layering", with multiple containers sharing underlying layers, decreasing resource usage. Ref: Docker Ecosystem - DO 10 / 36
- 11. Advantages Lightweight resource utilization: instead of virtualizing an entire operating system, containers isolate at the process level and use the host's kernel. Portability: all of the dependencies for a containerized application are bundled inside of the container, allowing it to run on any Docker host. Predictability: The host does not care about what is running inside of the container and the container does not care about which host it is running on. The interfaces are standardized and the interactions are predictable. 11 / 36 Docker Typically, when designing an application or service to use Docker, it works best to break out functionality into individual containers, a design recently known as micro-service architecture. This gives you the ability to easily scale or update components independently in the future. Having this exibility is one of the many reasons that people are interested in Docker for development and deployment. Ref: Docker Ecosystem - DO
- 12. Docker Engine Getting Started 12 / 36
- 13. Docker Engine When people say "Docker" they typically mean Docker Engine, the client-server application made up of the Docker daemon, a REST API that speci es interfaces for interacting with the daemon, and a command line interface (CLI) client that talks to the daemon (through the REST API wrapper). Docker Engine accepts docker commands from the CLI, such as dockerrun<image>, dockerpsto list running containers, dockerimagesto list images, and so on. Engine is the core of Docker and nothing else will run without it. Ref: docker.com 13 / 36
- 14. Docker Architecture 14 / 36
- 15. Docker daemon The Docker daemon runs on a host machine. The user does not directly interact with the daemon, but instead through the Docker client. Docker client The Docker client, in the form of the docker binary, is the primary user interface to Docker. It accepts commands from the user and communicates back and forth with a Docker daemon. Ref: docker.com 15 / 36 Docker Architecture Docker uses a client-server architecture. The Docker client talks to the Docker daemon, which does the heavy lifting of building, running, and distributing your Docker containers. Both the Docker client and the daemon can run on the same system, or you can connect a Docker client to a remote Docker daemon. The Docker client and daemon communicate via sockets or through a RESTful API.
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- 17. Let's Try It ... My Case: amd64 Machine, Ubuntu 16.04 17 / 36
- 18. $curl-fsSLhttps://get.docker.com/|sh $dockerinfo Containers:1 ... Images:15 ServerVersion:1.11.1 StorageDriver:aufs ... LoggingDriver:json-file CgroupDriver:cgroupfs Plugins: ... KernelVersion:4.4.0-21-generic OperatingSystem:Ubuntu16.04LTS ... $dockerversion Client: Version: 1.11.1 APIversion: 1.23 Goversion: go1.5.4 Gitcommit: 5604cbe Built: TueApr2623:43:492016 OS/Arch: linux/amd64 Server: Version: 1.11.1 APIversion: 1.23 Goversion: go1.5.4 Gitcommit: 5604cbe Built: TueApr2623:43:492016 OS/Arch: linux/amd64 First Step Ref: Quickstart, Install Docker $dockerrunhello-world HellofromDocker. Thismessageshowsthatyourinstallationappearstobeworkin Togeneratethismessage,Dockertookthefollowingsteps: 1.TheDockerclientcontactedtheDockerdaemon. 2.TheDockerdaemonpulledthe"hello-world"imagefromthe 3.TheDockerdaemoncreatedanewcontainerfromthatimage executablethatproducestheoutputyouarecurrentlyread 4.TheDockerdaemonstreamedthatoutputtotheDockerclien toyourterminal. Totrysomethingmoreambitious,youcanrunanUbuntucontain $dockerrun-itubuntubash Shareimages,automateworkflows,andmorewithafreeDocker https://hub.docker.com Formoreexamplesandideas,visit: https://docs.docker.com/userguide/ 18 / 36
- 19. Try Some Commands $dockerimages REPOSITORY TAG SIZE em/notebook v1 864.9MB ubuntu 16.04 120.1MB alpine 3.3 4.798MB busybox latest 1.113MB firecyberice/whalesay latest 47.25MB hello-world latest 960B docker/whalesay latest 247MB $JOB=$(dockerrun-dubuntu/bin/sh-c"whiletrue;doechoHelloworld;sleep1;done" $dockerstop$JOB $dockerstart$JOB $dockerrestart$JOB $dockerkill$JOB $dockerstop$JOB #Containermustbestoppedtoremoveit $dockerrm$JOB $dockerrm-f$JOB #Runningcontainer $dockerrun--rmfirecyberice/whalesayHelloDocker ______________ <HelloDocker> -------------- ## . ###### == ########## === /"""""""""""""""""___/=== ~~~{~~~~~~~~~~~~~~~~~/ ===-~~~ ______o __/ __/ ___________/ $dockerps-a CONTAINERID IMAGE COMMAND 2f6f337530d5 hello-world "/hello" e71dbedafb57 em/notebook:v1 "tini--jupyternote $dockerrm-f2f6f 2f6f $dockerps-a CONTAINERID IMAGE COMMAND e71dbedafb57 em/notebook:v1 "tini--jupyternote $dockerrun-it--entrypoint/bin/shfirecyberice/whalesay 19 / 36
- 20. $dockerrun-d-P--namewebnginx 224a61ea84cfbf468bd090aebbd0ba534e9b07bb8e7e0068bfaeca1ba72f754b $dockerps CONTAINERID IMAGE COMMAND CREATED STATUS PORTS 224a61ea84cf nginx "nginx-g'daemonoff" e71dbedafb57 em/notebook:v1 "tini--jupyternote" $dockerportweb 443/tcp->0.0.0.0:32768 80/tcp->0.0.0.0:32769 $dockerstopweb $dockerrmweb nginx 20 / 36
- 21. Mount a Volume on the Container Ref: docker.com $mkdirmysite&&cdmysite mysite$echo"mynewsite">index.html mysite$dockerrun-d-P-v$(pwd):/usr/share/nginx/html--namemywebnginx da01817c28bbdb2f3b71275ba7b9560da4e65f8716329c16787c83181760534c mysite$dockerportmyweb 443/tcp->0.0.0.0:32770 80/tcp->0.0.0.0:32771 mysite$echo"thisiscool">cool.html $dockerstopmyweb $dockerrmmyweb 21 / 36
- 22. Custom Images 22 / 36
- 23. Build Custom Image Ref: Build your own image $mkdirmydockerbuild&&cdmydockerbuild/&&touchDockerfile $dockerbuild-tdocker-whale. SendingbuildcontexttoDockerdaemon2.048kB Step1:FROMdocker/whalesay:latest --->6b362a9f73eb Step2:RUNapt-get-yupdate&&apt-getinstall-yfortunes --->Runningin7375f27597d7 ... Step3:CMD/usr/games/fortune-a|cowsay --->Runningin09c57e3ebb83 --->428cbace4310 Removingintermediatecontainer09c57e3ebb83 Successfullybuilt428cbace4310 Dockerfile FROMdocker/whalesay:latest RUNapt-get-yupdate&&apt-getinstall-yfortunes CMD/usr/games/fortune-a|cowsay $dockerrundocker-whale ________________________________________ /Ontheotherhand,lifecanbean |endlessparadeofTRANSSEXUALQUILTING| |BEESaboardacruiseshipto | DISNEYWORLDifonlyweletit!! / ---------------------------------------- ## . ###### == ######## === /""""""""""""""""___/=== ~~~{~~~~~~~~~~~~~~~~/ ===-~~~ ______o __/ __/ __________/ 23 / 36
- 25. $dockerrun--namemyredis-itubuntu:16.04bash root@ac6002b2a98b:/#apt-getupdate root@ac6002b2a98b:/#apt-getinstallwget root@ac6002b2a98b:/#apt-getinstallbuild-essentialtcl8.5 root@ac6002b2a98b:/#wgethttp://download.redis.io/redis-stable.tar.gz root@ac6002b2a98b:/#tarxzfredis-stable.tar.gz root@ac6002b2a98b:/#cdredis-stable&&make&&makeinstall root@ac6002b2a98b:/#./redis-stable/utils/install_server.sh ... Selectedconfig: Port :6379 Configfile :/etc/redis/6379.conf Logfile :/var/log/redis_6379.log Datadir :/var/lib/redis/6379 Executable :/usr/local/bin/redis-server CliExecutable:/usr/local/bin/redis-cli Isthisok?ThenpressENTERtogoonorCtrl-Ctoabort. Copied/tmp/6379.conf=>/etc/init.d/redis_6379 Installingservice... Success! StartingRedisserver... Installationsuccessful Manual Process test/myredis:v1 Ref: Getting Started with Docker root@ac6002b2a98b:/redis-stable#psax|grepredis root@ac6002b2a98b:/redis-stable#src/redis-cli 127.0.0.1:6379>setfoobar OK 127.0.0.1:6379>getfoo "bar" 127.0.0.1:6379>exit root@ac6002b2a98b:/redis-stable#exit $dockerps-a $dockercommit-m"addredis"-a"em"myredistest/myredis:v1 sha256:9b75a94f67cb47b012f445ed65fb13fc67d05a00ad1bb262d20ba4d $dockerimages|grepredis test/myredis v1 9b75a94f67cb 39secondsago 408.3MB 25 / 36
- 26. Dockerfile test/myredis:df $dockerbuild-ttest/myredis:df. $dockerimages|grepredis test/myredis df 9a450ae418d8 Aboutaminuteago 408.6 test/myredis v1 9b75a94f67cb 13minutesago 408.3 $dockerrun-d-p6379:6379test/myredis:df 1240a12b56e4a87dfe89e4ca4400eb1cafde802ac0187a54776f9ea54bb7f74f $dockerps CONTAINERID IMAGE COMMAND CREATED STATUS PORTS 1240a12b56e4 test/myredis:df "redis-server" $sudoapt-getinstallredis-tools $redis-cli 127.0.0.1:6379>setbatman OK 127.0.0.1:6379>getbat "man" 127.0.0.1:6379>quit FROMubuntu:16.04 RUNapt-getupdate RUNapt-getinstall-ywget RUNapt-getinstall-ybuild-essentialtcl8.5 RUNwgethttp://download.redis.io/redis-stable.tar.gz RUNtarxzfredis-stable.tar.gz RUNcdredis-stable&&make&&makeinstall RUN./redis-stable/utils/install_server.sh EXPOSE6379 ENTRYPOINT ["redis-server"] 26 / 36
- 27. Docker Compose 27 / 36
- 28. Docker Compose Compose is a tool for de ning and running multi-container Docker applications. With Compose, you use a Compose le to con gure your application's services. Then, using a single command, you create and start all the services from your con guration. Using Compose is basically a three-step process: 1. De ne your app's environment with a Docker le so it can be reproduced anywhere. 2. De ne the services that make up your app in docker- compose.yml so they can be run together in an isolated environment. 3. Lastly, run docker-compose up and Compose will start and run your entire app. Ref: Overview of Docker Compose 28 / 36
- 30. Getting Started Step #1 app.py requirements.txt flask redis Ref: Getting Started fromflaskimportFlask fromredisimportRedis app=Flask(__name__) redis=Redis(host='redis',port=6379) @app.route('/') defhello(): redis.incr('hits') return'HelloWorld!Ihavebeenseen%stimes.'%redis.g if__name__=="__main__": app.run(host="0.0.0.0",debug=True) 30 / 36
- 31. Dockerfile FROMpython:2.7 ADD./code WORKDIR/code RUNpipinstall-rrequirements.txt CMDpythonapp.py $dockerbuild-tweb. $dockerimages|grepweb web latest d6f25a9bf632 2minutesago 667.7MB Getting Started Step #2 31 / 36
- 34. Refs 34 / 36
- 35. Refs 1. Docker Introduction 2. Docker - Documentation 3. Docker Ecosystem - Digital Ocean 4. LXC vs. Docker - Flockport 5. CLIs Reference docker ps 6. Open Container Initiative 7. Getting Started with Docker 8. Docker Compose - Getting Started 35 / 36
- 36. END Eueung Mulyana http://eueung.github.io/docker-stuff/intro CodeLabs | Attribution-ShareAlike CC BY-SA 36 / 36