Docker is a platform that allows you to build, ship, and run applications inside lightweight, isolated environments called containers.
Containers package your application code + dependencies + configuration together.
This makes sure your app runs the same way on any machine whether it’s your laptop, a server, or the cloud.
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Why Use Docker?
- Problem Without Docker Solution With Docker
- “It works on my machine!” problem Same environment everywhere
- Difficult to set up dependencies All dependencies packed in container
- Heavy virtual machines Lightweight containers
- Deployment errors Fast, consistent deployments
Key Concepts
Image A blueprint (template) of your app (e.g., Node.js + code + dependencies).
How Docker Works
You write a Dockerfile
(e.g., which base image to use, how to run your app).
You build an image
→ docker build -t myapp .
You run a container
→ docker run -p 8080:80 myapp.
Example: Simple Dockerfile
# Use base image
FROM node:18
# Set working directory
WORKDIR /app
# Start the app
CMD [“npm”, “start”]
# Expose port
EXPOSE 3000
# Install dependencies
RUN npm install
Benefits
- Works the same on all systems.
- Faster development and deployment
- Easier scalability (works great with Kubernetes)
- Uses fewer resources than virtual machines
Basic Docker Commands
- docker –version Check Docker version
- docker build -t myapp . Build image
- docker images List images
- docker run -p 8080:80 myapp Run container
- docker ps List running containers
- docker stop <id> Stop container
- docker rm <id> Remove container
- docker rmi <id> Remove image
Docker in .NET / ASP.NET Core
In .NET projects, Docker helps you:
- Package your app + runtime together
- Deploy easily on any OS
- Use multi-stage builds to reduce image size
- Combine with SQL Server, Redis, etc., using Docker Compose
Example command:
dotnet publish -c Release
docker build -t myapp .
docker run -p 5000:80 myapp
Conclusion
Docker makes development faster, deployment smoother, and collaboration easier. It eliminates the “it works on my machine” problem and ensures your ASP.NET Core applications run consistently anywhere — skills you’ll gain from the Best ASP.NET Core Full Stack Academy in Kerala.
