The document provides an overview of Docker containers and how to get started with Docker. It discusses what containers are, how Docker works, the differences between containers and VMs, and how to use basic Docker commands. It also covers creating Docker images using Dockerfiles and provides examples of common Dockerfile commands.

1. Getting started on
Docker and containers
Presentation by - Priyadarshini Anand

2. Agenda
 Container
 Docker
 Inside container/ outside container
 Container Vs. VM
 Why are docker containers light weight?
 Basics of docker system
 Play with docker commands
 Docker file

3. Container
 Isolated process(es)
 Runs at native speed straight on host
 Owns process space
 Owns network stack
 Owns root file system
 Owns IPC
 Shares kernal with host

4. Docker
 A platform for developing, shipping and running applications using container
virtualization technology
 An Open source project to commoditize LinuX Containers
 Allows creation and sharing docker images
 Uses copy-on-write for quick images
 Client/ server architecture

5. Inside container
 My code
 My Libraries
 My package manager
 My app
 My data
Outside container
 Logging
 Remote access
 Network configuration
 Monitoring

6. Containers vs. VM
App
A
Hypervisor (Type 2)
Host OS
Server
Gues
t
OS
Bins/
Libs
App
A’
Gues
t
OS
Bins/
Libs
App
B
Gues
t
OS
Bins/
Libs
AppA’
Docker
Host OS
Server
Bins/LibsAppA Bins/Libs
AppB
AppB’
AppB’
AppB’
Container
Containers are isolated,
but share OS and, where
appropriate,
bins/libraries
Gues
t
OS
Gues
t
OS
…result is significantly faster
deployment, much less overhead,
easier migration, faster restart

7. Why are docker containers light weight?
Original App
(No OS to take
up space, resources,
or require restart)
App
A
Bins/
Libs
App
A’
Gues
t
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
Gues
t
OS
Bins/
Libs
Copy of
App
No OS. Can
Share bins/libs
Bins/
Libs
App
A
App
A
Gues
t
OS
Gues
t
OS
VMs Containers
AppΔBins

8. Basics of Docker System
Source Code
Repository
Dockerfile
For
A
Docker Engine
Build
Docker
Host 2 OS (Linux)Container
A
Container
B
Container
C
Push
Search
Pull
Run
Host 1 OS
(Linux)
ContainerA
Docker
Container
Image
Registry

9. Play with docker commands
 Check docker version
#docker version
 List local images
#docker images (latest, tag, local image pulled first)
 List containers
#docker ps
#docker ps –a
 Check logs
#docker logs <container id>
#docker logs –f <container id>

10. Play with docker commands
 Create container (with terminal/ detached/ with volume/ with port mapping)
Docker run [options] [image] [command] [args]
#docker run ubuntu:14.04 echo “hello world”
#docker run –i –t ubuntu:latest /bin/bash
#docker run –d centos:7 ping 127.0.0.1 –c 50
#docker run –i –t –v /myvolume nginx:1.7
#docker run –d –P tomcat:7

11. Play with docker commands

13. Play with docker commands
 Save changes in container as a new image
#docker run –i –t ubuntu:14.04 bash
#root@0c424bc93f0a:/#apt-get install curl
#root@0c424bc93f0a:/#exit
#docker commit 0c424bc93f0a sspt-artifactory.juniper.net/csp-myapp:1.0
#docker images
 Find resource(cpu, memory, io) usage by container
# docker stats –no-stream=true <container-id>

14. Play with docker commands
 Other useful commands
#docker history [image id]
#docker inspect [container name] | grep IPAddress
#docker start [container short id]
#docker stop [container short id]
#docker exec –i –t [container short id] /bin/bash
#docker rm [container short id]
#docker rmi [image-name:tag/ image id]
#docker save <image-name> > /home/image.tar
#docker load < /home/image.tar

15. Docker file
 Configuration file that contains instructions for building docker image
 More effective way to build images compared to using “docker commit”
 Easily fits into CI/ CD process
 Use “docker build” command to create image using docker file
 Daemon runs instructions one-by-one, committing the result of each
instruction to a new image, finally outputting the ID of new new image
 ENTRYPOINT instruction inside dockerfile defines command to run when a
container is executed

16. Dockerfile commands
 FROM
 ADD
 ENTRYPOINT
 ENV
 EXPOSE
 MAINTAINER
 RUN
 USER
 VOLUME
 WORKDIR

17. # Get base ubuntu image
FROM artifactory.net/my-ubuntu
# Copy installables
COPY client/ /opt/my-service-build/client/
COPY conf/*.conf /etc/my-service/
RUN mkdir /var/log/my-service
RUN
cd /opt/my-service-build &&
cd core-server &&
pip install --pre -rrequirements.txt -rtest-requirements.txt
&&
pip install my-services -f dist/ &&
RUN chmod +x /my-service-docker-entry.sh
ENTRYPOINT ["/my-service-docker-entry.sh”]
Sample Docker file

18. Play with Docker file
 Set ENV to set environment variables inside container:
ENV myName="John Doe" myDog=Rex The Dog
myCat=fluffy
and
ENV myName John Doe
ENV myDog Rex The Dog
ENV myCat fluffy
will yield the same net results in the final container, but the first form is
preferred because it produces a single cache layer.
 Change env variable using command – docker run --env <key>=<value>