Multi-Stage Build Optimizer

Intermediate15 minTrending

Reduce Docker image size dramatically by using multi-stage builds to separate build dependencies from the runtime image.

Prerequisites

-Docker installed
-A Dockerfile to optimize

Steps

Check current image size

See how large the existing image is before optimization.

$ docker images --format 'table {{.Repository}}\t{{.Tag}}\t{{.Size}}' | head -10

Build with target stage for development

Build only up to a specific stage in a multi-stage Dockerfile.

$ docker build --target builder -t myapp:dev .

Use --target to build intermediate stages for debugging or development without running the full build.

Build the production image

Build the final slim production image with only runtime dependencies.

$ docker build -t myapp:prod .

Compare image sizes

Verify the size reduction between development and production images.

$ docker images myapp

Inspect image layers

See what each layer contributes to the image size.

$ docker history myapp:prod --format 'table {{.Size}}\t{{.CreatedBy}}' --no-trunc

Full Script

full-script.sh

#!/bin/bash
# Multi-Stage Build Optimizer
set -euo pipefail

IMAGE_NAME=${1:?"Usage: $0 <image-name>"}

echo "=== Current Image Size ==="
docker images "$IMAGE_NAME" --format 'table {{.Repository}}\t{{.Tag}}\t{{.Size}}' 2>/dev/null || echo "Image not found"

echo ""
echo "=== Building production image ==="
docker build -t "$IMAGE_NAME:optimized" .

echo ""
echo "=== Image Comparison ==="
docker images "$IMAGE_NAME" --format 'table {{.Repository}}\t{{.Tag}}\t{{.Size}}'

echo ""
echo "=== Layer Analysis ==="
docker history "$IMAGE_NAME:optimized" --format 'table {{.Size}}\t{{.CreatedBy}}' | head -15

echo ""
echo "=== Optimization Tips ==="
echo "1. Use alpine or distroless as final base"
echo "2. Combine RUN commands to reduce layers"
echo "3. Order Dockerfile commands by change frequency (least to most)"
echo "4. Use .dockerignore to exclude unnecessary files"
echo "5. Copy only required artifacts from builder stage"

FAQ

Discussion

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#!/bin/bash # Multi-Stage Build Optimizer set -euo pipefail IMAGE_NAME=${1:?"Usage: $0 <image-name>"} echo "=== Current Image Size ===" docker images "$IMAGE_NAME" --format 'table {{.Repository}}\t{{.Tag}}\t{{.Size}}' 2>/dev/null || echo "Image not found" echo "" echo "=== Building production image ===" docker build -t "$IMAGE_NAME:optimized" . echo "" echo "=== Image Comparison ===" docker images "$IMAGE_NAME" --format 'table {{.Repository}}\t{{.Tag}}\t{{.Size}}' echo "" echo "=== Layer Analysis ===" docker history "$IMAGE_NAME:optimized" --format 'table {{.Size}}\t{{.CreatedBy}}' | head -15 echo "" echo "=== Optimization Tips ===" echo "1. Use alpine or distroless as final base" echo "2. Combine RUN commands to reduce layers" echo "3. Order Dockerfile commands by change frequency (least to most)" echo "4. Use .dockerignore to exclude unnecessary files" echo "5. Copy only required artifacts from builder stage"