Dive is a command-line tool that lets you explore Docker images layer-by-layer, showing exactly what each layer adds, modifies, or removes. It’s perfect for understanding image structure and identifying ways to reduce image size.

Installation:

# macOS
brew install dive

# Linux (various package managers available)
# Or via Docker
docker pull wagoodman/dive

Basic usage:

dive <image-name>

What it shows:

• Layer-by-layer breakdown: View image contents organized by individual layers
• Change tracking: Visual indicators show which files were added, removed, or modified
• Efficiency analysis: Identifies wasted space and provides a percentage score
• Size impact: See how much each layer contributes to the total image size

Build and analyze in one command:

dive build -t my-image:latest .

CI/CD integration:

Set efficiency thresholds to fail builds with bloated images:

CI=true dive <image-name>

This tool is invaluable for optimizing Dockerfiles, understanding why images are large, and catching unnecessary files that accidentally made it into production images.

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