This document introduces Docker, a lightweight container virtualization platform. It discusses how Docker uses Linux kernel features like namespaces and control groups to provide isolation similar to virtual machines but with less overhead. Docker images act as templates to launch containers which contain all dependencies for running applications. The document demonstrates how to install Docker, run containers from images, and manage images and containers. It explains key Docker components like images, containers, registries and repositories. Finally, it encourages getting involved in open source Docker projects.

1. Introduction To Docker
Lalatendu Mohanty
Twitter: @lalatenduM
Software Engineer @Red Hat

2. What we want?
● Scalability, maintainability, Agility, Portability.
● A continuum of abstraction levels.
● Improved resource utilization.

3. Linux Containers

4. Linux Containers
● Use Linux kernel isolation features to give a VM
like environment.
● Docker may be a two years old project, but
Linux containers are older than that.
● Docker, Lxc, Rkt, lmctfy

5. Docker

6. Introducing Docker
● Sand boxing of process/Application.
● Lightweight container virtualization platform.
● It is an application packaging and delivery
technology.

7. Why Docker?

8. Why Docker?
● I already have virtualization, do I need Docker?
– Yes, because it an awesome way of shipping
application.
– It reduces the time , from developing an application
to putting it in to production.
– Each Docker container can be an independent
entity.
– Different run time for different containers.

9. Docker Vs Virtualization
● Lighter than Virtual machines.
● Take less time to start
● We can run a ton of processes on a reasonably
sized host
● Deploying and scaling relatively easy.
● “Dockerized” apps are completely portable.

10. Technologies Behind Docker
● Control groups
– It is a Linux kernel feature.
– allocate resources i.e. CPU time, system memory,
network bandwidth, or combinations of these
resources to a process/ processes.
● Union file systems
– layered file system, so you can have a read only part,
and a write part, and merge those together.
– E.g. : AUFS, btrfs, vfs, and DeviceMapper

11. Technologies Behind Docker
● Namespaces
– It helps to create isolated workspace.
– When you run a container, Docker creates a set of
namespaces for that container.
● Selinux
– SELinux provides secure separation of containers
by applying SELinux policy and labels
● There are some more ....

13. Docker Components
● Image
– It is a template which is used to launch containers.
● Container
– It is like a directory. A Docker container holds
everything that is needed for an application to run.

14. Docker Components
● Registry
– It stores and serves up the actual image assets,
and it delegates authentication to the index.
● Repository
– A registry holds a collection of named repositories,
which themselves are a collection of images
tracked by GUIDs.

15. Demo
● Install docker RPM
– $yum install docker-io
● Start the docker demon
– $systemctl start docker
● Enable docker service. So that, it automatically start
after reboot
– $systemctl enable docker
● For details about installation, check :
http://docs.docker.com/installation/fedora/

16. ● #Search an image
– $docker search name
● #Download an image
– $docker pull fedora
● #List images
– $docker images
● #Run image.
– $docker run -t -i fedora /bin/bash

17. ● #Stop a container
– $docker stop <ID/Name>
● #kill a container
– $docker kill container_name
● #Run a script inside a container
● #Save the change
– $docker diff ID/name
– $docker commit -m lalatendu -a testscript 7f28a2303254
centos7:test_container
● #Remove the image
– $docker rmi image_name
● #Remove the container
– $docker rm container_name

18. This slide is available at :
http://www.slideshare.net/then4way/docker-
quick-start

19. Get involved
● https://github.com/docker
● https://github.com/coreos
● https://github.com/projectatomic

20. Thank You :-)
Any questions please?