2.  You are a employee at some XYZ company. You are in backend development
department of that company and there are other departments also like
administrator, frontend, customer service, testing, cloud, etc…
 You are developing a WEB APP.
 This WEB APP has many dependencies so in order to work seemly for all
departments at this project they have to define some constraints.
 So that this APP run same in all the departments system!
 Its kind of a hectic task!
 There can be many problems!
 So what's the solution for it?

4.  LXC (Linux Containers) is a Linux operating system level virtualization method for
running multiple isolated Linux systems on a single host.
 Linux containers, in short, contain applications in a way that keep them isolated from
the host system that they run on.
 Containers allow a developer to package up an application with all of the parts it
needs, such as libraries and other dependencies, and ship it all out as one package.
 In a way, containers behave like a virtual machine. To the outside world, they can look
like their own complete system.
 But unlike a virtual machine, rather than creating a whole virtual operating system,
containers don't need to replicate an entire operating system, only the individual
components they need in order to operate.
 This gives a significant performance boost and reduces the size of the application.
 They also operate much faster, as unlike traditional virtualization the process is
essentially running natively on its host, just with an additional layer of protection
around it.

6. • Docker is a container management service. The keywords
of Docker are develop, ship and run anywhere. The whole
idea of Docker is for developers to easily develop
applications, ship them into containers which can then be
deployed anywhere.
• Docker containers wrap up a piece of software in a
complete file system 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.

7.  Docker has the ability to reduce the size of development by providing a smaller
footprint of the operating system via containers.
 With containers, it becomes easier for teams across different units, such as
development, QA and Operations to work seamlessly across applications.
 You can deploy Docker containers anywhere, on any physical and virtual machines
and even on the cloud.
 Since Docker containers are pretty lightweight, they are very easily scalable.

8. API endpoint
Static website
nginx 1.5 + modsecurity + openssl + bootstrap 2
User DB
postgresql + pgv8 + v8
Analytics DB
hadoop + hive + thrift + OpenJDK
Web frontend
Ruby + Rails + sass + Unicorn
Queue
Redis +redis-sentinel
Background workers
Python 3.0 + celery + pyredis + libcurl + ffmpeg + libopencv + nodejs +
phantomjs
Python 2.7 + Flask + pyredis + celery + psycopg + postgresql-client
Development VM
QAserver
Public Cloud
Disaster recovery
Contributor’s laptop
Production Servers
Multiplicityof
Stacks
Multiplicityof
hardware
environment
s
Production Cluster
Customer Data Center
Doservicesand
appsinteract
appropriately?
CanImigrate
smoothlyand
quickly?

9. Static website User DB Web frontend Queue Analytics DB
Development
VM
QAserver Public Cloud Contributor’s
laptop
Multiplicityof
Stacks
Multiplicityof
hardware
environments
Production
Cluster
Customer Data
Center
Doservicesand
appsinteract
appropriately?
CanImigrate
smoothlyand
quickly
…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…

10. 10

11.  Build once, runanywhere
 A clean,safe, hygienic and portable runtime environment for yourapp.
 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

12.  Automate testing, integration, packaging…anything you can script
 Reduce/eliminate concerns about compatibility on different platforms, either
your own or your customers.
 Cheap, zero-penalty containers to deploy services? A VM without the overhead of
a VM? Instant replay and reset of image snapshots? That’s the power of Docker

13.  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
customerenvironments

14.  Support segregation of duties.
 Significantly improves the speed and reliability of continuous deployment
and continuous integration systems.
 Because the containers are so lightweight, address significant performance,
costs, deployment, and portability issues normally associated with VMs.

15. • The Developer
• Worries about
what’s “inside”
the container
• His code
• His Libraries
• His
Package
Manager
• His Apps
• His Data
• All Linux
servers look
the same
• The Administrator
• Worries about
what’s “outside”
the container
• Logging
• Remote access
• Monitoring
• Network config
• All containers
start, stop, copy,
attach, migrate,
etc. the same way

16. Source
Code
Repository
Dockerfile
For
A
Docker Engine
Docker
Container
Image
Registry
Build
Docker
Host 2 OS (Linux)
ContainerA
ContainerB
ContainerC
ContainerA
Push
Search Pull
Run
Host 1OS(Linux)

17.  Docker takes advantage of a technology called namespaces to provide the
isolated workspace we call the container.
 When you run a container, Docker creates a set of namespace for that container.
 Some of the namespaces that Docker Engine uses on Linux are:-
• The pid namespace: Process isolation (PID: Process ID).
• The net namespace:Managing network interfaces .
• The ipc namespace:Managing access to IPC resources (IPC: InterProcess
Communication).
• The mnt namespace: Managing mount-points (MNT: Mount).
• The uts namespace: Isolating kernel and version identifiers. (UTS: Unix
Timesharing System)

18.  Docker Engine on Linux also makes use of another
technology called cgroups or control groups.
 A key to running applications in isolation is to have them only use the
resources you want.
 This ensures containers are good multi-tenant citizens on a host.
 Control groups allow Docker Engine to share available hardware resources to
containers and, if required, set up limits and constraints.
 For example, limiting the memory available to a specific container.

20. Docker Engine is a client-server application with these
major components:
• A server which is a type of long-running program called a daemon process.
• A REST API which specifies interfaces that programs can use to talk to the
daemon and instruct it what to do.
• A command line interface (CLI) client.

22. •A Docker image is a read-only template. For example,
an image could contain an Ubuntu operating system
with Apache and your web application installed.
•Images are used to create Docker containers. Docker
provides a simple way to build new images or update
existing images, or you can download Docker images
that other people have alreadycreated.
•Docker images are the build component of Docker.

23. •Docker can build images automatically by reading the
instructions from a DockerFile.
•A Dockerfile is a text document that contains all the
commands a user could call on the command line to assemble an
image.
•Using docker build users can create an automated build that
executes several command-line instructions in succession.
•The docker build command builds an image from a Dockerfile
and acontext.

25. •Docker registries hold images.
•These are public or private stores from which you upload
or download images.
•The public Docker registry is provided with the Docker
Hub. (hub.docker.com)
•It serves a huge collection of existing images for your use. These
can be images you create yourself or you can use images that
others have previously created.
•Docker registries are the distribution component of
Docker.

26. •The CLI makes use of the Docker REST API to control or
interact with the Docker daemon through scripting or direct
CLIcommands.
•Many other Docker applications make use of the
underlying API andCLI.
•The CLI is also used to issue commands.

28.  Persisted snapshot that can be run
 images: List all local images
 run: Create a container from an image and execute a command in
it
 tag: Tag an image
 pull: Download image from repository
 rmi: Delete a local image
 This will also remove intermediate images if no longer used
28

29.  Runnable instance of an image
 ps: List all running containers
 ps –a: List all containers (incl. stopped)
 top: Display processes of a container
 start: Start a stopped container
 stop: Stop a running container
 pause: Pause all processes within a container
 rm: Delete a container
 commit: Create an image from a container
29