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Working with Docker CLI
Dockerfile and Image Creation
Learning Outcome
5
Understand base images and common Docker commands
4
Build a Docker image from a Dockerfile
3
Create a basic Dockerfile
2
Explain what a Dockerfile is
Explain what a Dockerfile is
1
Understand what Docker CLI is and how it is used
Earlier, we learned that
Analogy
Imagine you are baking a cake
You follow a recipe that lists:
Ingredients
Steps to bake a cake
Instructions to create cake
Anyone who follows the same recipe will produce the same cake
What is Docker CLI?
Docker CLI stands for Docker Command Line Interface
It is the tool used to interact with Docker using commands
Using Docker CLI, users can:
Build Docker images
Run containers
Stop containers
Pull images from repositories
Push images to repositories
Docker CLI communicates with the Docker Daemon to perform operations
Example command:
docker version
This command checks the Docker client and server version
Common Docker CLI Commands
Some frequently used Docker CLI commands:
Check Docker version
docker version
List Docker images
docker images
Run a container
docker run nginx
List running containers
docker ps
Stop a container
docker stop container_idRemove a container
docker rm container_id
These commands help manage images and containers
What is a Dockerfile?
A Dockerfile is a text file that contains instructions to build a Docker image automatically
Base image
It defines:
Application files
Dependencies
Commands to run inside the container
Using a Dockerfile ensures:
Consistent builds
Automated image creation
Easy application deployment
Structure of a Dockerfile
A Dockerfile usually contains the following instructions:
Defines the base image
FROM
WORKDIR
Sets the working directory inside the container
Copies files from host to container
COPY
RUN
Executes commands during image build
CMD
Defines the default command when container starts
Example:
FROM ubuntu
RUN apt update
CMD ["echo","Hello Docker"]
How to Create a Dockerfile
Now the Dockerfile is ready
What is a Base Image?
A Base Image is the starting point for building a Docker image.
It provides the basic operating system environment
Examples of base images:
ubuntu
alpine
centos
node
python
Example:
FROM ubuntuThis means the container will use Ubuntu as the base system
Why base images are needed:
Provide operating system environment
Provide required runtime
Simplify image creation
How to Build an Image from a Dockerfile
After creating a Dockerfile, we build an image
Command:
docker build -t myimage Explanation
docker build → build image
-t → tag (name of image)
myimage → image name
. → current directory (Dockerfile location)
Example output:
Docker reads Dockerfile instructions and builds the image step by step
Running a Container from the Image
Once the image is created, we can run a container
Command:
This creates and runs a container using the image
docker run myimagedocker run -d nginx
Run container in background
docker run --name webserver nginx
Assign container name
docker run -p 80:80 nginx
Map ports
Docker Image Build Workflow
Deployment workflow:
Developer → Build Image → Store Image → Run Container
Summary
5
Running containers from images
4
Building Docker images
3
Understanding base images
2
Creating a Dockerfile
1
Using Docker CLI commands
Quiz
Which symbol is used to access variable value ?
A. #
B. &
C. $
D. @
Quiz-Answer
Which symbol is used to access variable value ?
A. #
B. &
C. $
D. @
Permission 755 gives full access to
A. Group
B. Others
C. Owner
D. Everyone
Copy of Containerization Fundamentals
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