Containerizing a Node.js App with Docker 🐳

In my learning journey, I recently deployed a simple Node.js application inside a Docker container. This hands-on experience allowed me to understand the process of containerizing an app and running it in an isolated environment. Here's a breakdown of the steps I followed:

Prerequisites: Install Visual Studio Code, Node.js, Docker, Docker Desktop.

Step 1: Create a Node app in the projects folder:

npx create-react-app testapp

cd testapp

npm start

Delete the node_modules directory as we will install it via the Dockerfile. (Note: We can install it with npm install).

Step 2: Create a Dockerfile with instructions for building the container image inside testapp:

FROM node:14

WORKDIR /myapp

COPY . .

RUN npm install

EXPOSE 3000

CMD ["npm", "start"]

Step 3: Build the Docker image from the Dockerfile:

docker build -t mywebapp:01 .

It will build the image in the current directory.

Step 4: Run the container from the built image:

docker run -d --rm --name "mywebcontainer" -p 3001:3000 mywebapp:01

This command runs the container in detached mode, removes it automatically after stopping, names it "mywebcontainer," and maps the host port 3001 to the container port 3000.

Note: We can use this image multiple times to build multiple containers because they are environment isolated.

Step 5: Verify the running container:

docker ps -a

It will show all process statuses.

Step 6: Access the app outside the container by visiting http://localhost:3001 in my browser.

Throughout this process, I learned about Docker concepts like images, containers, port mapping, and container management commands like docker ps, docker stop, docker rm, and more.

• To stop container: docker stop ContainerName
• To remove container: docker rm ContainerName
• To remove image: docker rmi imgId
• To give image a name: docker build -t mywebapp:01 .

Containerizing applications is becoming increasingly important in modern software development, and Docker simplifies the process of creating, deploying, and running applications in isolated environments. This hands-on experience has deepened my understanding of containerization and has motivated me to further explore Docker and its ecosystem.