What's Docker
Docker is a containerization platform that packages applications with all dependencies into portable utils called containers.
Learn the foundational concepts of Docker
Core concepts:
- Image: A read-only blueprint containing app code,libraries,and environment settings.
- Container: A running instance of an image.
- Dockerfile: Script defining how to build an image.
- Volume: Persistent storage outside the container lifecycle.
- Network: Enables communication between containers.
Example: Building and Running a Container
FROM node:18
WORKDIR /app
COPY package.json ./
RUN npm install
COPY .
EXPOSE 3000
CMD ["npm", "start"]
docker build -t my-node-app
docker run -p 3000:3000 my-node-app
Managing Multi-Container Apps with Docker Compose
version: '3'
services:
app:
build:
ports:
- "3000:3000"
depends_on:
- mongo
mongo:
image: mongo
volumes:
- mongo-data:/data/db
volumes:
mongo-data:
RUN with:
docker-compose up
Best Practices
- Use
.dockerignore to exclude unnecessary files(e.g.,.git,node_modules).
- Avoid
:latest tags;pin versions for stability.
- Run containers as non-root for security.
- Use multi-stage builds to reduce image size.
- Store secrets in
.env files or Docker secrets, not in images.
When to Use Docker
- [Y] Consistent dev/prod environments
- [N] Small static sites or quick scripts where setup overhead outweighs benefits.
Next Steps
- Learn Docker networking(bridge, host, overlay)for container communication.
- Explore Docker volumes for persistent data.
- Integrate Docker into CI/CD pipelines for automated builds and deployments.
With these fundamentals, you can confidently containerize, run, and manage applications in any environment.