The document provides an overview of getting started with Docker. It discusses what Docker is, how containerization differs from virtualization, and how to install Docker. It covers building Docker images using Dockerfiles, the difference between images and containers, and common Docker commands. The document also compares traditional deployment workflows to those using Docker, demonstrating how Docker can help ensure consistency across environments.

1. Getting started with
Docker
Geeta Vinnakota

2. Next 45 minutes
 What is docker and how can it help us?
 What is containerization and why does that matter?
 How is containerization different from virtualization?
How to install docker on Linux?
What is an image?
How do you build an image?
 What is a Dockerfile and why is it necessary?
How is a container different from an image?
 How does a docker deployment work flow with look like?
Command Reference
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3. Why Docker?
• Eliminate “But it works on my computer!” nightmares during deployments, by
exactly mirroring development and production environments
• Support quick replication of new production servers ~ within minutes
• Allows quick rollbacks ~ within minutes
• Advanced multi-container dockers play well with micro-service architecture by
enabling de-coupling and portability
( Keep an eye out and ask yourself, how these benefits are realized in the workflow, as you proceed with
the deck )
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4. What is Docker?
• What is Docker?
• Docker manages containers
• Docker allows shipping applications, code and services in containers
• What is a container?
• Containers can be compared to virtual machines, but much light-weight, faster with
less overhead
• Containers are isolated, independent, portable and easily reproducible
• Containerization vs Virtualization
• For an abstract view, containerization can be compared with virtualization
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5. Virtualization
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Image by Laura Frank, Sr Developer at Codeship
• Here is a host computer
with an installed hypervisor
• Hypervisor supports virtual
machines on a host
computer
• There are 3 virtual
machines installed on a
host in this diagram
• They share the resources of
the host computer

6. Containerization
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Image by Laura Frank, Sr Developer at Codeship
• Here is another host
computer
• Notice, that there is no
hypervisor or guest OS

7. Containerization
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Image by Laura Frank, Sr Developer at Codeship
• Instead of a hypervisor,
there is a container engine
• 3 containers are running
on the container engine
Docker ecosystem
provides us with a
container engine along
with a set of tools that
help us build and manage
containers

8. Installation
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9. Installating docker on Linux (ubuntu)
sudo apt-get update get latest package version
curl –sSL https://get.docker.com/ | sh install docker
docker -v check version
sudo usermod –aG docker ubuntu add default user ubuntu to docker group
docker info
docker history
• Linux – Package Installation described above
• Mac/Windows – Docker Toolbox. ( boot2docker is old and deprecated )

10. Images
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11. What is an image?
• An image is a template for a container
• It could be a simple command or complex software
• An image layer is a file system that is read-only
• A R-W file system is installed on top of the image layers
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12. How image builds work?
• After each RUN docker looks for a matching image in the build cache
• Build command compresses the context into an archive/tar and sends
it to the daemon
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13. How is an image different from a container?
Image
• Image is similar to a class in
programming
• Image ~ Blueprint
• Image is what you store on docker hub
& pass around
Container
• Container is similar an instance of the class
• Container ~ Actual Object
• You do not store containers anywhere or
pass them around
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• Consider the following differences and analogies to avoid confusion between images and
containers.

14. Types of Images
Service Image Project Base Image Official Image
• Offers a service out of the box
• You have to do very little to get
it functioning
• Nginx, Postgres, MySQL
• No service is offered out of the
box
• Ruby, Language based images
• Add your own code on top of
the image
• Maintained by the organization
or company itself
• An official image can serve as a
service or project based image
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15. Image Command Reference
Build an Image docker build –t repo_name/img_name:tag . build images from Dockerfile and
context
-t Tag the image with a repo name
Repo Name –
username/imagename
Rename docker tag local_repo:tag
docker_hub_repo:tag
Rename an image
docker tag img_id docker_hub_repo:tag Rename an image
List docker images List images
Remove docker rmi –f img_id/img_name Remove image
Inspect Details docker inspect img_id/img_name List port bindings, config
Login to Docker Hub docker login –username=uname –
password=pw –email=email
Pull Image from Hub docker pull username/image_name:tag

16. What is Dockerfile?
• A Dockerfile lets you create your own image
• It is a series of instructions to build your own image
• INSTRUCTIONS are typically upper case
• Best Practices
• Split long commands with backslashes
• Prefer COPY to ADD
• Minimize image layers by combining multiple RUN commands to avoid
multiple intermediate images, keeping readability in mind.
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17. Dockerfile Instruction Reference
Instruction Example Details
FROM FROM nginx Mandatory. First instruction.
Specifies base image
RUN RUN rm
/etc/nginx/defa
ult.conf
Execute the command while on the container
WORKDIR WORKDIR
/users/dan
Specify the working directory for the RUN commands
By default they are run in the root directory
CMD ping localhost Specify the default command of the image, that is run, when the
container is launched.
If there are multiple, the last one takes precedence
Process that runs with the container

18. Dockerfile Instruction Reference
EXPOSE EXPOSE 80 Expose ports on the container.
Does not map them to hosts
VOLUME VOLUME /var/log/nginx Creates a mount point with the specified name.
Marks it as holding volumes from native host
Does not map any volumes from the host
COPY COPY build/artifacts
/usr/share/nginx/html
Copies files from host to container
ADD Similar to COPY, but has additional capabilities of uncompressing
tar files, fetching files from remote locations
Prefer COPY to ADD unless specifically required
ENTRYPOINT Similar to CMD

19. Containers
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20. What is a container?
• Typically containers run a single process(default command).
Containers can be thought of, as the process they run.
• Container runs only as long as the default command is running
• Container itself is a process in the host machine. Any process run by
the container is a child process
• Containers have internal IP address
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21. How is a container different from a Virtual
Machine
• Container looks and operates like a Virtual Machine, but it is not a VM
• Containers are light weight. Spin up faster
• A host can accommodate more containers than VMs
• Containers run on top of docker engine
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22. Container Best Practices & Usecases
• Best Practices
• Specify names for containers to avoid strange auto generated names
• Containers are not suitable for persistent data, as they are ephemeral and
should allow stopping, destroying and recreating
• Do not run ssh servers in containers unless needed
• Use docker commands to check logs, restart processes, tweak configuration,
run upgrades
• Usecases
• Deploy web front-end applications
• Deploy web APIs
• Run Maintenance scripts
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23. Container Command Reference
Purpose Example Details
Run a container docker run –name docker-nginx –p
80:80 –d nginx
Creates a container with name
docker-nginx from image nginx
Flags for run -d Detached mode. Container runs in
the background and keeps running
until manually stopped
-p 80:80 Map local machine port 80 to
container port 80
Inspect docker inspect container_id | grep
IpAddress
List docker ps -a List containers including those that
are stopped

24. Troubleshooting a Container
Stop a container docker stop c_id Stop container with id c_id
Remove docker rm c_name Remove container with name
c_name
Enter a container docker exec –it c_id bash Takes you inside of a running
container to the bash
-it interactive ( also works with run
)
View logs from container docker logs c_id print logs of pid 1 process from the
container
docker logs –f c_id Follow logs from the container
docker logs –f –tail 10 c_id Follow logs from the last 10 lines

25. What is Docker Hub?
• Place to store and distribute docker images
• Think of it as github but for docker images
• Docker logo or prefix of library ‘library/nginx’ denotes official images
in the hub
• 70+ official, 100K+ regular, 300M+ downloads
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26. Traditional Deployment Workflow
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27. 2/4/2016 26
• In a traditional
deployment flow, you
start with the host
machine
Traditional Deployment Workflow – Step 1 of 5

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• Install the
necessary tools
and services
• Start with
Installing Nginx
Nginx
Traditional Deployment Workflow – Step 2 of 5

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• Then more
software
provisioning
and
installations
• Ruby platform
Nginx
Ruby
Traditional Deployment Workflow – Step 3 of 5

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• Install the
necessary
dependencies
Nginx
Ruby
Dependencies
Traditional Deployment Workflow – Step 4 of 5

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• Finally deploy
the application
code and tie
everything
together into
an ecosystem
Nginx
Ruby
Dependencies
Application
Traditional Deployment Workflow – Step 5 of 5

32. Deployment Workflow with
Docker
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33. 2/4/2016 32
• In Docker deployment
flow, we start with
installing docker enginer
on the host computer
• Cloud providers like
AWS provide machines
pre-provisioned with
docker, ready to use
Docker
Engine
Deployment Workflow with Docker – Step 1 of 2

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• Ship the entire
ecosystem, as a
container from your
development
environment ( as
opposed to
provisioning each
software separately )
Nginx
Ruby
Dependencies
Application
Docker
Engine
Deployment Workflow with Docker – Step 2 of 2

35. Production
Server
Docker
Image
Prd
Deploy
Package
Staging
Server
QA
Deploy
Package
Development
Machine
Image =
Application Code +
Software Needed to Run
the code
Deploy Package =
Location of Image on Hub
+ Access Credentials
• Image is nothing but a
versioned artifact
• Notice how all 3 versions
run the same image
• Which is what leads to no
surprise deploys ( exact
mirroring of development,
staging and production
servers

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Code Change
Create new docker image
docker build –t
repo/username:tag .
Push image to docker hub
docker push
repo/username:tag
Update image tag version
in dockerrun.aws.json
Web
or
CLI
Create a zip file (use gulp) with
dockerrun.aws.json &
.ebextensions. Upload it via
webconsole
CLI
’eb deploy’ Uploads a zip of
dockerrun.aws.json &
.ebextensions
Web CLI
Deploy Workflow
Docker using EB (Elastic
Beanstalk)
Tells Elastic Beanstalk
the location of the
docker image
Eliminate unrequired
files in image build by
adding .dockerignore
Tell EB to to pick only
dockerrun.aws.json
while create zip via
.ebignore

37. Advanced Features
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38. Volumes
• Volumes are mounted when creating a container
• Data in this volume is persistent even if the container is deleted
• Volumes are independent of the container lifecycle
• Volumes can be shared between containers
• Specify volumes in dockerfile using VOLUME instruction
• Best Practices:
• Mounting volumes from host for persistent data is not recommended as it
binds you to that host
• Cannot map volumes from host using dockerfile as it is intended to work on
any host
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39. Container Linking
• Container connection without using any network ports
• Step-1: Create the source container
• Step-2: Create the recipient container, with link to the source. It
creates an entry in the recipient with an alias and IP of the source
• Usecase: when you have separate web and database containers
• Source and recipient Containers can be on the same or different hosts
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