Container image size impacts deployment time, storage costs, and security exposure. Large images containing unnecessary packages increase attack surface. Optimization techniques produce smaller, faster, more secure images without sacrificing functionality.
Size Reduction Techniques
Multi-stage builds separate build dependencies from runtime images. Alpine or distroless base images minimize OS footprint. Layer optimization reduces redundant data. Dependency pruning removes development packages from production images.
- Use multi-stage builds keeping build tools out of final images
- Choose minimal base images—Alpine, distroless, or scratch
- Order Dockerfile instructions to maximize layer caching
- Remove package manager caches and unnecessary files
- Use .dockerignore to exclude build context bloat
Security Hardening
Scan images for vulnerabilities before deployment. Run as non-root users preventing privilege escalation. Use read-only filesystems where possible. Pin base image versions for reproducibility. Regular rebuilds incorporate security patches from base images.