Docker Image Size Comparison

Audience: DevOps engineers, contributors

WHAT

Size and capability comparison across DockerKit image variants (original, multistage, minimal, distroless).

WHY

Choosing the right image variant requires understanding the trade-offs between size, functionality, and security posture.

HOW

Build Results

Image Variant Size Reduction Description
dck:original 108MB Baseline Single-stage Alpine with all tools
dck:multistage 108MB 0% Multi-stage build with validation
dck:minimal 30.4MB -72% Scratch-based with essential binaries
dck:distroless 3.26MB -97% Ultra-minimal distroless (limited functionality)

Analysis

Original vs Multistage (108MB each)

  • Both images have the same size because they include the same runtime dependencies
  • Multistage advantage: Build-time validation with shellcheck
  • Multistage advantage: Better layer caching and cleaner build process

Minimal Image (30.4MB - 72% reduction)

  • Built from scratch with only essential binaries
  • Includes: bash, curl, jq, docker-cli
  • Trade-off: Limited shell utilities (uses busybox)
  • Best for: Production environments where size matters

Distroless Image (3.26MB - 97% reduction)

  • Ultra-minimal with just a Go binary placeholder
  • Trade-off: No shell, limited functionality
  • Would require rewriting DCK as a compiled binary
  • Best for: Highly secure, minimal attack surface deployments

Recommendations

  1. Development: Use Dockerfile (original) for full tooling
  2. CI/CD: Use Dockerfile.multistage for build validation
  3. Production: Use Dockerfile.minimal for good balance of size and functionality
  4. High Security: Consider Dockerfile.distroless with compiled DCK binary

Build Commands 

# Original
docker build -f Dockerfile -t dck:latest .

# Multi-stage
docker build -f Dockerfile.multistage -t dck:multistage .

# Minimal
docker build -f Dockerfile.minimal -t dck:minimal .

# Distroless (experimental)
docker build -f Dockerfile.distroless -t dck:distroless .

Security Scan Results

Run security scans on the minimal production image:

docker scout cves dck:minimal
trivy image dck:minimal