Hey everyone! 👋
Welcome to Day 2 of my 40 Days of Kubernetes journey! Today, I’m diving into the practical side of Docker: Dockerizing an application. 🐳
This post is all about writing a Dockerfile, containerizing an application, and managing it using essential Docker commands. I’m sharing my learnings, mistakes, and insights as I go—so let’s get started!
🚀 What You’ll Learn:
1. Dockerfile Demystified: What is a Dockerfile, and how to write one.
2. Dockerizing Your Application: Step-by-step containerization.
3. Docker Command Breakdown: Explanation of commonly used Docker commands.
4. Essential Docker Commands: How to manage containers effectively.
🛠️ Tools and Resources
If you want to follow along, here are some resources you can use:
1. Docker and Kubernetes Sandbox Environments:
2. Download Docker Desktop:
🏗️ Step-by-Step: Dockerizing a Project
I decided to use a simple Node.js application for this task. You can either use your project or clone the one I used:
1. Clone the Git Repository
Run the following command to get the sample project:
git clone https://github.com/docker/getting-started-app.git
cd getting-started-app/
2. Create a Dockerfile
Create an empty file named Dockerfile:
touch Dockerfile
3. Write the Dockerfile
Open the file in a text editor and add the following content:
FROM node:18-alpine
WORKDIR /app
COPY . .
RUN yarn install --production
CMD ["node", "src/index.js"]
EXPOSE 3000
Explanation of Each Line:
• FROM: Specifies the base image (Node.js in this case).
• WORKDIR: Sets the working directory inside the container.
• COPY: Copies the application files into the container.
• RUN: Installs production dependencies.
• CMD: Defines the command to run when the container starts.
• EXPOSE: Exposes port 3000 for the app.
4. Build the Docker Image
Run the following command to build your Docker image:
docker build -t day02-todo .
5. Verify the Image
Check if the image was created successfully:
docker images
6. Push the Image to Docker Hub
Create a repository on Docker Hub, then run these commands:
docker login
docker tag day02-todo:latest username/repo-name:tag
docker push username/repo-name:tag
7. Run the Container
Pull and run the container in a new environment:
docker pull username/repo-name:tag
docker run -dp 3000:3000 username/repo-name:tag
8. Access the Application
Open http://localhost:3000 in your browser to see your app running! 🎉
9. Explore More Commands
• To enter the container:
docker exec -it <container_id> sh
• To view logs:
docker logs <container_id>
✍️ Key Takeaways
Here’s what I learned today:
• A Dockerfile is the recipe for building Docker images.
• Writing a clean and efficient Dockerfile is key to smooth containerization.
• The docker run command bridges the gap between images and running containers.
• Managing images and containers with commands like docker exec and docker logs makes debugging easier.
Task 2/40
1. Dockerize Your Application:
• Either clone a GitHub project or use your own app.
• Write a Dockerfile and follow the steps above.
• Push your image to Docker Hub.
2. Explore docker init:
• This command simplifies Dockerfile creation. Try it and see how it works for your project.
3. Share Your Learnings:
• Write a blog or share a LinkedIn/Twitter update.
• Don’t forget to tag @PiyushSachdeva, @CloudOps Community, and use #40daysofkubernetes.
📂 GitHub Repository
GitHub repo You’ll find the Dockerfile and step-by-step instructions here.
📽️ Watch the Video
Here’s a quick walkthrough for visual learners! 👇
Let’s keep learning together—see you on Day 3! 🚀