Docker Optimize Command

Command

/docker-optimize

Description

Analyzes your Dockerfile(s) and docker-compose configuration to identify optimization opportunities. Produces a rewritten Dockerfile with multi-stage builds, optimized layer ordering, security hardening, and size reduction.

Behavior

1. Read existing Dockerfile(s) and docker-compose.yml
2. Analyze current image size, layer count, and build time
3. Identify optimization opportunities
4. Generate an optimized Dockerfile with explanations
5. Compare before/after metrics

Optimization Checklist

Image Size Reduction

• Use slim/alpine base images where possible
• Multi-stage builds to separate build and runtime
• Remove build dependencies from final image
• Clean package manager caches (apt-get clean, npm cache clean)
• Use .dockerignore to exclude unnecessary files
• Minimize layer count by combining RUN commands

Build Speed

• Order layers from least to most frequently changed
• Copy dependency manifests before source code
• Leverage build cache effectively
• Use --mount=type=cache for package manager caches
• Parallelize independent build stages

Security

• Pin base image versions (no latest tag)
• Run as non-root user
• No secrets in build args or layers
• Scan for known vulnerabilities
• Minimal runtime packages (no curl, wget in production)
• Read-only filesystem where possible

Output Format

Optimized Dockerfile Example (Node.js)

Copy
# Stage 1: Dependencies
FROM node:20-alpine AS deps
WORKDIR /app
COPY package.json package-lock.json ./
RUN --mount=type=cache,target=/root/.npm \
    npm ci --only=production

# Stage 2: Build
FROM node:20-alpine AS build
WORKDIR /app
COPY package.json package-lock.json ./
RUN --mount=type=cache,target=/root/.npm \
    npm ci
COPY . .
RUN npm run build

# Stage 3: Runtime
FROM node:20-alpine AS runtime
WORKDIR /app

# Security: non-root user
RUN addgroup -g 1001 appgroup && \
    adduser -u 1001 -G appgroup -s /bin/sh -D appuser

# Copy only production artifacts
COPY --from=deps /app/node_modules ./node_modules
COPY --from=build /app/dist ./dist
COPY --from=build /app/package.json ./

USER appuser
EXPOSE 3000
HEALTHCHECK --interval=30s CMD wget -qO- http://localhost:3000/health || exit 1
CMD ["node", "dist/index.js"]

Comparison Report

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## Optimization Results

| Metric | Before | After | Improvement |
|--------|--------|-------|-------------|
| Image Size | 1.2 GB | 185 MB | -85% |
| Layers | 23 | 12 | -48% |
| Build Time | 4m 30s | 1m 45s | -61% |
| CVEs | 12 | 0 | -100% |
| Runs as Root | Yes | No | Fixed |

Examples

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# Optimize the project Dockerfile
/docker-optimize

# Optimize with specific base image preference
/docker-optimize --base alpine

# Include docker-compose optimization
/docker-optimize --include-compose