Getting Started with Docker for Developers

1. What Docker is and its key components.
2. Installing Docker on your system.
3. Basic Docker CLI commands.
4. Creating your first Docker image and container.

What is Docker?

Docker Components: The Building Blocks

• Docker Engine: This is the heart of Docker. It’s what allows you to create and manage containers. The Docker Engine works as a client-server application. The client (Docker CLI) sends commands to the Docker Daemon (the server), which does the heavy lifting using RESTful APIs.
• Docker Container: Think of a container like a shipping container that stores goods. In Docker’s case, it stores everything your application needs to run—source code, libraries, tools, etc. Containers are created from Docker images and are run by the Docker Engine.
• Docker Image: If containers are the runtime environments, Docker images are the templates. A Docker image is a static snapshot of everything your application needs to run. You create a container from a Docker image, meaning the image is the blueprint, and the container is the execution.
• Dockerfile: A Dockerfile is a script containing a series of instructions that Docker reads to build a Docker image. This file automates the process of setting up your application environment by specifying things like dependencies, file locations, and commands to run.
• Docker Hub: Just like GitHub is the go-to place for storing and sharing code, Docker Hub is the cloud-based repository for Docker images. You can push your custom images to Docker Hub and pull them onto any system with Docker installed.

Getting Your Hands Dirty: Installing Docker

1. Visit docker.com and download Docker Desktop for your operating system.
2. Run the installer and follow the on-screen instructions.
3. Once installed, sign in or sign up for a Docker account.
4. Verify the installation by running the following command in your terminal or command prompt:

docker -v

Essential Docker Commands: Your Quick Reference Guide

docker images

docker pull <image_name>:<tag>

docker build -t <image_name>:<tag> <path_to_dockerfile>

docker ps

docker run <image-name>

docker stop <name>

docker login

docker tag <image-name> <username>/<repo-name>

docker push <username>/<repo-name>

Let’s Build Something: Creating Your First Docker Image

let msg = 'Hello, I am learning Docker with Sainty!';
console.log(msg);

FROM node:18-alpine
COPY . /app
WORKDIR /app
CMD ["node", "msg.js"]

• FROM node:18-alpine: This sets the base image to Node.js version 18 on Alpine Linux.
• COPY . /app: Copies all files from the current directory to a directory named /app inside the container.
• WORKDIR /app: Sets /app as the working directory.
• CMD ["node", "msg.js"]: Runs the command node msg.js when the container starts.

docker build -t hello-docker .

docker run hello-docker

Wrapping Up