🚢 Docker Basics: Commands and Dockerfile Components

📚 Introduction

As I continue my 12-day Docker learning series, today’s session was packed with hands-on experience!
In this blog, I’ll share:

Some essential Docker commands I practiced.
A theoretical overview of Dockerfile components — the blueprint for building Docker images.

If you are new to Docker or want a quick refresher, this will be a perfect guide.

🛠️ Basic Docker Commands You Must Know

Here are some of the fundamental Docker commands I learnt today:

Command	Purpose
`docker --version`	Check the installed Docker version
`docker pull <image>`	Download an image from Docker Hub
`docker images`	List all downloaded images
`docker run <image>`	Run a container from an image
`docker ps`	List running containers
`docker ps -a`	List all containers (running + stopped)
`docker stop <container_id>`	Stop a running container
`docker rm <container_id>`	Remove a stopped container
`docker rmi <image_id>`	Remove a Docker image
`docker exec -it <container_id> bash`	Access the shell inside a running container

📌 Quick Tips:

Image: A snapshot/template used to create containers.
Container: A running instance of an image.
Always remove unused images/containers to free up space!

🏗️ Understanding Dockerfile Components

A Dockerfile is a text document that contains all the commands to assemble an image.

Here are the key components of a Dockerfile:

Instruction	Purpose
`FROM`	Sets the base image for building the new image
`RUN`	Executes commands inside the image during build time
`CMD`	Provides default commands to run when a container is created
`LABEL`	Adds metadata to the image (like version, description)
`EXPOSE`	Informs Docker that the container listens on specific network ports
`ENV`	Sets environment variables
`COPY`	Copies files/folders from the local machine to the container
`ADD`	Similar to COPY but can handle remote URLs and unpack archives
`WORKDIR`	Sets the working directory inside the container
`ENTRYPOINT`	Configures a container to run as an executable

📈 Example: A Simple Dockerfile

dockerfileCopyEdit# Use an official Python runtime as a base image
FROM python:3.9-slim

# Set working directory
WORKDIR /app

# Copy current directory contents into the container at /app
COPY . /app

# Install any needed packages
RUN pip install --no-cache-dir -r requirements.txt

# Make port 80 available to the world outside this container
EXPOSE 80

# Run app.py when the container launches
CMD ["python", "app.py"]

✨ Final Thoughts

Today’s learning really built the foundation for working with Docker practically.
Understanding basic commands and Dockerfile instructions is crucial before diving into building and deploying real-world applications using Docker.

Stay tuned for Day 3 where I’ll move deeper into image creation and container management! 🚀

🔖 Tags

#Docker #DockerCommands #Dockerfile #DevOps #Containers #LearningSeries

Docker Essentials: Mastering Basic Commands and Dockerfile Components