Dcoker 2nd article

  

Introduction to Docker

Docker is an open-source platform that automates the deployment of applications inside software containers. This ensures that the software behaves the same way, regardless of where it is deployed. Docker achieves this by combining a lightweight container runtime with workflows and tooling that help manage and deploy applications.

Core Concepts of Docker

1. Docker Images A Docker image is a lightweight, standalone, executable package that includes everything needed to run a piece of software, including the code, runtime, libraries, environment variables, and config files.

Example Command: To pull an existing image from Docker Hub:

bas
docker pull ubuntu

2. Docker Containers A container is a runtime instance of an image—what the image becomes in memory when executed.

Example Command: To run a container from the ubuntu image:

bas
docker run -it ubuntu

3. Dockerfile A Dockerfile is a text document that contains all the commands a user could call on the command line to assemble an image.

Example Command: Creating a simple Dockerfile:

Dockerfile
FROM ubuntu RUN apt-get update && apt-get install -y nginx CMD ["nginx", "-g", "daemon off;"]

4. Docker Compose Docker Compose is a tool for defining and running multi-container Docker applications. With Compose, you use a YAML file to configure your application’s services.

Example Command: To start up a project using docker-compose:

bas
docker-compose up

5. Docker Hub Docker Hub is a service provided by Docker for finding and sharing container images with your team. It is a public registry that contains a large number of images available for use.

Example Command: To login to Docker Hub:

bash
docker login

Common Docker Commands and Their Usage

Command	Description	Example Usage
docker pull	Pulls an image from a registry	docker pull ubuntu
docker build	Builds an image from a Dockerfile	docker build -t myimage .
docker run	Runs a command in a new container	docker run -it ubuntu bash
docker push	Pushes an image to a registry	docker push myimage
docker exec	Runs a command in a running container	docker exec -it mycontainer bash
docker stop	Stops one or more running containers	docker stop mycontainer
docker start	Starts one or more stopped containers	docker start mycontainer
docker rm	Removes one or more containers	docker rm mycontainer
docker rmi	Removes one or more images	docker rmi myimage
docker logs	Fetches logs of a container	docker logs mycontainer
docker inspect	Returns low-level information on Docker objects	docker inspect mycontainer
docker network create	Creates a new network	docker network create mynetwork
docker volume create	Creates a volume for persistent data storage	docker volume create myvolume
docker compose up	Builds, (re)creates, starts, and attaches to containers	docker-compose up
docker compose down	Stops containers and removes containers, networks, volumes	docker-compose down