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Docker is a powerful tool for containerization, but following best practices ensures efficiency, security, and maintainability. Below are key Docker best practices with practical implementations.
You Should Know:
1. Use Small Base Images
Smaller images reduce attack surfaces and improve performance. Prefer Alpine Linux or `scratch` for minimal deployments.
FROM alpine:latest RUN apk add --no-cache python3
2. Multi-Stage Builds
Minimize final image size by discarding build dependencies.
Build stage FROM golang:1.18 AS builder WORKDIR /app COPY . . RUN go build -o myapp Final stage FROM alpine:latest COPY --from=builder /app/myapp /usr/local/bin/ CMD ["myapp"]
3. Pin Versions
Avoid “latest” tags to prevent unexpected updates.
FROM node:18.12.1
4. Use `.dockerignore`
Exclude unnecessary files (like `node_modules` or `.git`).
node_modules .git .log
5. Minimize RUN Layers
Chain commands to reduce layers.
RUN apt-get update && \ apt-get install -y curl && \ rm -rf /var/lib/apt/lists/
6. Avoid Running as Root
Enhance security by using a non-root user.
RUN useradd -m appuser && chown -R appuser /app USER appuser
7. Use `COPY` Instead of `ADD`
`COPY` is more predictable than `ADD` (which can extract archives).
COPY ./src /app/src
8. Health Checks
Ensure containers are running correctly.
HEALTHCHECK --interval=30s --timeout=3s \ CMD curl -f http://localhost/ || exit 1
9. Combine Related Instructions
Group related commands for better caching.
RUN apt-get update && \ apt-get install -y python3 pip && \ pip install flask
10. Clean Up After Install
Remove unnecessary files to reduce image size.
RUN apt-get install -y package && \ apt-get clean && \ rm -rf /var/lib/apt/lists/
11. Use Labels & Tags
Improve maintainability with metadata.
LABEL maintainer="[email protected]" LABEL version="1.0"
12. Prefer `ENTRYPOINT` Over `CMD`
Use `ENTRYPOINT` for immutable commands.
ENTRYPOINT ["python3"] CMD ["app.py"]
13. Limit Layers
Too many layers increase build time and image size.
14. Set `WORKDIR`
Define a working directory for consistency.
WORKDIR /app
15. Don’t Store Secrets
Use Docker secrets or environment variables.
docker run -e "API_KEY=12345" myapp
What Undercode Say:
Docker optimizations significantly improve security, performance, and maintainability. Small images, multi-stage builds, and proper layer management reduce vulnerabilities. Always follow least-privilege principles and automate health checks for resilient deployments.
Expected Output:
A secure, lightweight, and well-documented Docker container following industry best practices.
Prediction:
Future Docker enhancements will focus on AI-assisted builds, automated vulnerability scanning, and tighter Kubernetes integration.
Relevant URLs:
IT/Security Reporter URL:
Reported By: Sketechnews Docker – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
