Getting Started

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Getting Started#

Docker can be installed on various operating systems including Linux, macOS, and Windows. Follow the instructions on the official Docker installation page for your specific OS.

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Verify Installation

To verify Docker is installed correctly, open a terminal (or command prompt) and run:

docker --version

Running Your First Container

Run a simple container using the hello-world image:

docker run hello-world

This command downloads the hello-world image from Docker Hub (if not already present) and runs it in a container.

Working with Docker Images

  • Pull an Image:

docker pull ubuntu

  • List Images:

docker images

Creating a Dockerfile

Create a simple Dockerfile to define a custom image:

# Use an official Node.js runtime as a parent image
FROM node:14

# Set the working directory in the container
WORKDIR /usr/src/app

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

# Install the application dependencies
RUN npm install

# Make port 8080 available to the world outside this container
EXPOSE 8080

# Define the command to run the application
CMD ["node", "app.js"]

Save this file as Dockerfile in your project directory.

Building and Running a Docker Image

  • Build the Image

docker build -t my-node-app .

  • Run a Container

docker run -p 8080:8080 my-node-app

This command maps port 8080 on the host to port 8080 on the container.

Managing Containers

  • List Running Containers

docker ps

  • Stop a Container

docker stop <container_id>

  • Remove a Container

docker rm <container_id>

Using Docker Compose

Docker Compose is a tool for defining and running multi-container Docker applications. Use a docker-compose.yml file to configure your application’s services.

Example docker-compose.yml:

version: '3'
services:
web:
    build: .
    ports:
    - "8080:8080"
redis:
    image: "redis:alpine"

Benefits of Using Docker

  • Consistency and Reproducibility: Containers ensure applications run the same in development, testing, and production.

  • Isolation: Containers isolate applications from each other and the host system.

  • Efficiency: Containers are lightweight and use system resources more efficiently than VMs.

  • Portability: Docker containers can run on any system that supports Docker, making deployment straightforward.

  • Scalability: Docker can easily scale applications horizontally by adding more containers.

Conclusion

Docker revolutionizes how applications are developed, deployed, and managed by providing a consistent environment across various stages of the development lifecycle. By encapsulating applications and their dependencies in containers, Docker ensures reliability, portability, and efficiency, making it an essential tool in modern software development and DevOps practices.

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