What is Docker

Docker is a platform that allows you to package, distribute, and run applications within containers. Containers are lightweight, portable, and self-sufficient environments that encapsulate everything needed to run an application, including its code, runtime, system tools, libraries, and settings.


Key Concepts

  • Images Docker images are read-only templates that contain the application and its dependencies. They serve as the basis for creating containers.
  • Containers Containers are instances of Docker images. They are lightweight, portable, and isolated environments that run applications.
  • Dockerfile A Dockerfile is a text file that contains instructions for building Docker images. It specifies the environment and configuration for an application.
  • Docker Hub Docker Hub is a cloud-based registry service that hosts Docker images. It allows users to share and distribute images publicly or privately.

Getting Started

Installation

Install Docker Desktop from the official website. After installation, Docker CLI (docker) and Docker Compose (docker-compose) commands will be available in your terminal.


Basic Commands

  • docker run <image>: Runs a container based on the specified image.
  • docker pull <image>: Downloads an image from Docker Hub.
  • docker build <path>: Builds an image from a Dockerfile located at the specified path.
  • docker ps: Lists running containers.
  • docker images: Lists downloaded images.
  • docker stop <container>: Stops a running container.
  • docker rm <container>: Removes a container.
  • docker rmi <image>: Removes an image.

Creating a Dockerfile

Start by creating a new directory for your project. Create a file named Dockerfile in the project directory. Define the base image, copy application files, and specify commands to run the application. Example Dockerfile:

FROM python:3.9
WORKDIR /app
COPY . /app
RUN pip install -r requirements.txt
CMD ["python", "app.py"]

Building an Image

Navigate to the directory containing the Dockerfile. Run
docker build -t <image_name> . to build the image. Replace <image_name> with a name for your image.


Running a Container

Once the image is built, you can run a container using
docker run <image_name>. You can specify additional options such as port mappings, volume mounts, and environment variables.


Publishing to Docker Hub

Create a Docker Hub account if you haven’t already. Log in to Docker Hub using docker login. Tag your image with your Docker Hub username and repository name: docker tag <image_name> <username>/<repository_name>. Push the image to Docker Hub: docker push <username>/<repository_name>.


Conclusion

Docker simplifies the process of building, distributing, and running applications by leveraging containers. With Docker, you can package your applications with their dependencies, ensuring consistency and reproducibility across different environments. Experiment with Docker to discover its full potential!

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Last updated 22 Sep 2024, 12:15 CEST . history