Docker allows users to run isolated processes called containers. Containers leverage features of the host operating system like namespaces and cgroups to isolate resources and run multiple containers on a single host. Docker uses images which are read-only templates used to create containers. Images are composed of layered filesystems. The Dockerfile defines how to build an image. Docker provides tools to manage the entire container lifecycle from image management to container runs. It standardizes the package and distribution of applications as container images. This helped drive adoption of containers and microservices architectures in DevOps workflows.

1. Overview of
Containers and
Docker
Sudip Ghosh

2. What is a container ?
● Runtime Definition:
“A sandbox for a process” or
“An isolated process.”
● The container process and
the container lifecycle are
tightly coupled.
● Share OS Kernel
● bins/libraries
OS
P P P P
cgroups
Ps namespace

3. Creating a container :Cgroups and
namespace

4. Creating a container :Copy-on-write

5. Difference between VM and Container
Physical
OS
APP
Physical
OS
APP
VM Container
Hypervisor
(vsphere,NSX etc.)
Virtual Machine
NIC
Kernel
Agents
Storage
NIC
Storage
size DE
OS Dependencies
OS Dependencies

6. IMAGE
● A binary representation +
some metadata or state.
Ex:.vmdk is a disk image
● Images are made of layers,
conceptually stacked on top
of each other
Advantages:
● Consolidation of binary files
● Focus on specific place and
detect vulnerability
Scratch
Debian
perl
APP ..
..
..

7. Dockerfile
An environment in a
text file.
From:<base image>
………………
…………….
…………
…………
………
…………
……………….
…………………..
Dockerfile

8. Relationship between
Container,IMAGES,dockerfile
Conatiners
(like
instances)
IMAGES
(like classes or
blueprints)

9. What is Docker ?
● Docker is a computer program that performs
operating-system-level virtualization, also
known as "containerization". It was first
released in 2013 and is developed by Docker,
Inc. Docker is used to run software packages
called "containers"
● Repo: https://github.com/docker
● Idea of Mr. Solomon Hykes and team of dotcloud
and open source community

10. How Docker works and why it is so fast in terms of running a
container from an image
Docker Host
……
……
…….
Pull / Push
(Diff only)
Registry
cache
Image tree
Client
Daemon
API
Pull
Create
Commit
Run
etc.
-Container lifecycle
management
-network
-storage
N
V
Container Lifecycle
Management

11. Containers have been around for avery long time.(c.f. LXC,
Solaris Zones etc)
What does Docker bring to the table then ?

12. Commoditization of Containers

13. Shipping Containers Efficiently

14. Container image as build artifact

15. Technical and Cultural
revolution(DevOps)

16. Time to up some
Containers
Sudip Ghosh