Learn Docker - 1 Code Examples & CST Typing Practice Test
Docker is a platform for developing, shipping, and running applications inside lightweight, portable containers, enabling consistent environments across development, testing, and production.
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Learn DOCKER with Real Code Examples
Updated Nov 27, 2025
Code Sample Descriptions
Multi-stage Dockerfile
# Multi-stage Dockerfile for Node.js application
FROM node:18-alpine AS builder
# Set working directory
WORKDIR /app
# Copy package files
COPY package*.json ./
# Install dependencies
RUN npm ci --only=production
# Copy source code
COPY . .
# Build the application
RUN npm run build
# Production stage
FROM node:18-alpine AS production
# Create non-root user
RUN addgroup -g 1001 -S nodejs && \
adduser -S nextjs -u 1001
# Set working directory
WORKDIR /app
# Copy built application from builder stage
COPY --from=builder --chown=nextjs:nodejs /app/dist ./dist
COPY --from=builder --chown=nextjs:nodejs /app/node_modules ./node_modules
COPY --from=builder --chown=nextjs:nodejs /app/package.json ./package.json
# Health check
HEALTHCHECK --interval=30s --timeout=10s --start-period=60s --retries=3 \
CMD curl -f http://localhost:3000/health || exit 1
# Switch to non-root user
USER nextjs
# Expose port
EXPOSE 3000
# Set environment variables
ENV NODE_ENV=production
ENV PORT=3000
# Start the application
CMD ["npm", "start"]
Shows best practices for multi-stage builds, security considerations, and optimized Node.js container deployment.
Frequently Asked Questions about Docker
What is Docker?
Docker is a platform for developing, shipping, and running applications inside lightweight, portable containers, enabling consistent environments across development, testing, and production.
What are the primary use cases for Docker?
Packaging applications with dependencies into portable containers. Running microservices and cloud-native apps. Continuous integration/continuous deployment (CI/CD). Environment standardization across development, testing, and production. Simplifying deployment on cloud platforms or on-premises servers
What are the strengths of Docker?
Portability across environments. Resource-efficient compared to VMs. Rapid provisioning and scaling. Simplifies CI/CD pipelines. Strong ecosystem and community support
What are the limitations of Docker?
Requires learning Docker CLI and concepts. Container isolation not as strong as full VMs for security-sensitive workloads. Persistent storage requires careful management. Networking between containers can be complex. Performance overhead when running GUI or heavy I/O applications
How can I practice Docker typing speed?
CodeSpeedTest offers 1+ real Docker code examples for typing practice. You can measure your WPM, track accuracy, and improve your coding speed with guided exercises.