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      • Docker Performance Optimization

      This chapter covers Docker container performance optimization strategies, including image optimization, runtime tuning, and resource management.

      Image Size Optimization

      Choose the Right Base Image

      Base ImageSizeUse Case
      scratch0 MBStatically compiled languages (Go)
      alpine~5 MBMost scenarios
      distroless~20 MBHigh security requirements
      slim~80-200 MBNeed more system tools
      full~800 MB+Build stage

      Reduce Layers

      # ✅ Single RUN, fewer layers
RUN apt-get update && \
    apt-get install -y curl wget && \
    apt-get clean && \
    rm -rf /var/lib/apt/lists/*

      Multi-Stage Builds

      FROM node:20 AS builder
WORKDIR /app
COPY package*.json ./
RUN npm ci
COPY . .
RUN npm run build

FROM nginx:alpine
COPY --from=builder /app/dist /usr/share/nginx/html

      Build Speed Optimization

      Leverage Build Cache

      Place less-frequently-changing instructions first:

      COPY package*.json ./
RUN npm ci
COPY . .

      Use BuildKit

      DOCKER_BUILDKIT=1 docker build -t myapp .

      BuildKit benefits: parallel stage builds, smarter caching, better security.

      Cache Dependency Downloads

      RUN --mount=type=cache,target=/root/.cache/pip \
    pip install -r requirements.txt

      Runtime Optimization

      CPU

      docker run --cpus 2 myapp              # Max 2 CPUs
docker run --cpu-shares 512 myapp       # CPU weight (relative)
docker run --cpuset-cpus "0,1" myapp    # Pin to specific cores

      Memory

      docker run -m 512m myapp               # Max 512MB
docker run -m 512m --memory-swap 1g myapp  # Memory + swap = 1GB

      Storage

      docker run --tmpfs /tmp:rw,size=100m myapp   # tmpfs for temp files
docker run -v mydata:/data myapp             # Named volumes (faster than bind mounts)

      Network

      docker run --network host myapp   # Host network (best performance, no isolation)

      Resource Monitoring

      docker stats
docker stats --format "table {{.Name}}\t{{.CPUPerc}}\t{{.MemUsage}}"
docker system df
docker system df -v

      Cleanup

      docker system prune -a       # All unused resources
docker image prune -a        # Unused images
docker volume prune          # Unused volumes
docker builder prune         # Build cache

      Optimization Checklist

      OptimizationImpactPriority
      Use Alpine base imagesReduce image sizeHigh
      Multi-stage buildsReduce image sizeHigh
      Leverage build cacheSpeed up buildsHigh
      .dockerignoreSpeed up buildsMedium
      Merge RUN instructionsReduce layersMedium
      Resource limitsPrevent resource contentionHigh
      Named volumesImprove I/O performanceMedium
      Enable BuildKitSpeed up buildsMedium

      Chapter Summary

      Docker performance optimization spans both image building and container runtime. Choose appropriate base images, leverage build cache, and configure resource limits to significantly improve Docker efficiency.

      Further Reading