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Docker-Intro
- 1. Introduction to Docker January, 2016 @sujai_mba
- 2. Agenda • Introduction to Docker, Containers, and the Matrix from Hell • Why people care: Separation of Concerns? • How Docker works? • Technical explanation • Containers vs VMs • Basics of Docker System • Docker File • Docker CLI Commands
- 3. Static website Web frontend User DB Queue Analytics DB Background workers API endpoint nginx 1.5 + modsecurity + openssl + bootstrap 2 postgresql + pgv8 + v8 hadoop + hive + thrift + OpenJDK Ruby + Rails + sass + Unicorn Redis + redis-sentinel Python 3.0 + celery + pyredis + libcurl + ffmpeg + libopencv + nodejs + phantomjs Python 2.7 + Flask + pyredis + celery + psycopg + postgresql-client Development VM QA server Public Cloud Disaster recovery Contributor’s laptop Production Servers The ChallengeMultiplicityofStacks Multiplicityof hardware environments Production Cluster Customer Data Center Doservicesandapps interact appropriately? CanImigrate smoothlyand quickly?
- 4. The Matrix From Hell Static website Web frontend Background workers User DB Analytics DB Queue Development VM QA Server Single Prod Server Onsite Cluster Public Cloud Contributor’s laptop Customer Servers ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
- 6. ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Also a matrix from hell
- 7. MultiplicityofGoods Multiplicityof methodsfor transporting/storing DoIworryabout howgoodsinteract (e.g.coffeebeans nexttospices) CanItransport quicklyandsmoothly (e.g.fromboatto traintotruck) Solution: Intermodal Shipping Container …in between, can be loaded and unloaded, stacked, transported efficiently over long distances, and transferred from one mode of transport to another A standard container that is loaded with virtually any goods, and stays sealed until it reaches final delivery.
- 8. Static website Web frontendUser DB Queue Analytics DB Development VM QA server Public Cloud Contributor’s laptop Docker is a shipping container system for code MultiplicityofStacks Multiplicityof hardware environments Production Cluster Customer Data Center Doservicesandapps interact appropriately? CanImigrate smoothlyandquickly …that can be manipulated using standard operations and run consistently on virtually any hardware platform An engine that enables any payload to be encapsulated as a lightweight, portable, self-sufficient container…
- 9. Static website Web frontend Background workers User DB Analytics DB Queue Development VM QA Server Single Prod Server Onsite Cluster Public Cloud Contributor’s laptop Customer Servers Docker eliminates the matrix from Hell
- 10. Why Developers Care • Build once…(finally) run anywhere* • A clean, safe, hygienic and portable runtime environment for your app. • No worries about missing dependencies, packages and other pain points during subsequent deployments. • Run each app in its own isolated container, so you can run various versions of libraries and other dependencies for each app without worrying • Automate testing, integration, packaging • Reduce/eliminate concerns about compatibility on different platforms, either your own or your customers.
- 11. Why Devops Cares? • Configure once…run anything • Make the entire lifecycle more efficient, consistent, and repeatable • Increase the quality of code produced by developers. • Eliminate inconsistencies between development, test, production, and customer environments • Significantly improves the speed and reliability of continuous deployment and continuous integration systems • Because the containers are so lightweight, costs, deployment, and portability issues normally are associated with VMs
- 12. How Docker Works • You can build Docker images that hold your applications • You can create Docker containers from those Docker images to run your applications. • You can share those Docker images via Docker Hub or your own registry
- 13. More technical explanation • High Level—It’s a lightweight VM • Own process space • Own network interface • <<machine container>> • Low Level—It’s chroot on steroids • Container=isolated processes • Share kernel with host • <<application container>> • Run everywhere • Regardless of kernel version (2.6.32+) • Regardless of host distro • Physical or virtual, cloud or not • Container and host architecture must match* • Run anything • If it can run on the host, it can run in the container • i.e. if it can run on a Linux kernel, it can run WHY WHAT
- 14. App A Containers vs. VMs Hypervisor (Type 2) Host OS Server Guest OS Bins/ Libs App A’ Guest OS Bins/ Libs App B Guest OS Bins/ Libs AppA’ Docker Host OS Server Bins/Libs AppA Bins/Libs AppB AppB’ AppB’ AppB’ VM Container Containers are isolated, but share OS and, where appropriate, bins/libraries Guest OS Guest OS …result is significantly faster deployment, much less overhead, easier migration, faster restart
- 15. Why are Docker containers lightweight? Bins/ Libs App A Original App (No OS to take up space, resources, or require restart) AppΔ Bins/ App A Bins/ Libs App A’ Guest OS Bins/ Libs Modified App Copy on write capabilities allow us to only save the diffs Between container A and container A’ VMs Every app, every copy of an app, and every slight modification of the app requires a new virtual server App A Guest OS Bins/ Libs Copy of App No OS. Can Share bins/libs App A Guest OS Guest OS VMs Containers
- 16. Basics of the Docker system Source Code Repository Dockerfile For A Docker Engine Docker Image Registry Build Docker Host 2 OS (Linux) ContainerA ContainerB ContainerC ContainerA Push Search Pull Run Host 1 OS (Linux) Docker Image Run
- 17. Changes and Updates Docker Engine Docker Image Registry Docker Engine Push Update Bins/ Libs App A Base Image Host is now running A’’ Container Mod A’’ AppΔ Bins/ Bins/ Libs App A Bins/ Bins/ Libs App A’’ Host running A wants to upgrade to A’’. Requests update. Gets only diffs Container Mod A’ Bins/ AppΔ
- 18. Docker File • Like a Makefile (shell script with keywords) • Extends from a Base Image • Results in a new Docker Image • Imperative, not Declarative • A Docker file lists the steps needed to build an images • docker build is used to run a Docker file • Can define default command for docker run, ports to expose, etc