Dive¶

# ============================================
# DIVE CONFIGURATION
# ============================================

# Keybindings
keybinding:
  # Layer navigation
  toggle-collapse-dir: Ctrl+Space
  toggle-aggregate-layer: Ctrl+A
  toggle-added-files: Ctrl+A
  toggle-removed-files: Ctrl+R
  toggle-modified-files: Ctrl+M
  toggle-unmodified-files: Ctrl+U

  # Pane navigation
  page-up: PageUp
  page-down: PageDown
  filter-files: Ctrl+F

# Display
diff:
  # Show diffs in tree
  hide: []

# Performance
layer:
  # Show layer command
  show-aggregated-changes: false

# CI/CD thresholds
rules:
  - name: "Efficiency check"
    trigger: "image-efficiency"
    message: "Image efficiency below threshold"
    # Fail if efficiency < 95%
    threshold: 0.95

  - name: "Wasted space check"
    trigger: "user-wasted-percent"
    message: "Too much wasted space"
    # Fail if wasted space > 5%
    threshold: 0.05

# CI mode (non-interactive)
export CI=true

# Custom config path
export DIVE_CONFIG_PATH=~/.config/dive.yaml

# Source
export DIVE_SOURCE=docker  # docker, podman, docker-archive

# 1. Analyze current image
dive myapp:latest

# Look for:
# - Large layers (inefficient COPY commands)
# - Removed files (wasted space - files added then deleted)
# - Duplicate files across layers

# 2. Common issues and fixes:

# BAD: Multiple RUN commands create layers
RUN apt-get update
RUN apt-get install -y curl
RUN apt-get clean

# GOOD: Chain commands, clean in same layer
RUN apt-get update && \
    apt-get install -y curl && \
    apt-get clean && \
    rm -rf /var/lib/apt/lists/*

# BAD: COPY then modify creates wasted space
COPY . /app
RUN rm -rf /app/tests /app/.git

# GOOD: Use .dockerignore or COPY selectively
COPY src/ /app/src/
COPY package.json /app/

# BAD: Install dev dependencies
RUN npm install

# GOOD: Production only
RUN npm ci --only=production

# In CI pipeline (GitLab CI example)
image-scan:
  stage: test
  image: wagoodman/dive:latest
  script:
    - dive --ci ${CI_REGISTRY_IMAGE}:${CI_COMMIT_SHA}
  only:
    - merge_requests

# GitHub Actions example
- name: Dive image scan
  uses: yuichielectric/dive-action@0.0.4
  with:
    image: 'myapp:${{ github.sha }}'
    config-file: '.dive-ci'

rules:
  - name: "Efficiency > 95%"
    trigger: "image-efficiency"
    threshold: 0.95

  - name: "Wasted space < 100MB"
    trigger: "user-wasted-bytes"
    threshold: 104857600  # 100MB in bytes

# Build two versions
docker build -t myapp:v1 .
# (make optimizations)
docker build -t myapp:v2 .

# Compare sizes
dive myapp:v1 --json v1.json
dive myapp:v2 --json v2.json

# Manual comparison or use jq
jq '.layer | length' v1.json  # Number of layers
jq '.layer | length' v2.json

Efficiency = (Total Image Size - Wasted Space) / Total Image Size × 100%

Image efficiency: 93.5%
  Total image size: 152 MB
  Potential waste: 10 MB

Layer count: 8
  Largest layer: 45 MB (apt packages)

Wasted space by layer:
  Layer 3: 8 MB (removed .git directory)
  Layer 6: 2 MB (apt cache)

# ============================================
# OPTIMIZED DOCKERFILE
# ============================================

# Use specific, slim base image
FROM python:3.11-slim as builder

# Install build dependencies in one layer
RUN apt-get update && \
    apt-get install -y --no-install-recommends \
        gcc \
        g++ \
        make && \
    rm -rf /var/lib/apt/lists/*

# Copy only dependency files first (better caching)
COPY requirements.txt .

# Install Python dependencies
RUN pip install --no-cache-dir --user -r requirements.txt

# ============================================
# FINAL STAGE
# ============================================

FROM python:3.11-slim

# Copy only installed packages from builder
COPY --from=builder /root/.local /root/.local

# Copy application code
COPY src/ /app/src/
COPY config/ /app/config/

# Make sure scripts are in PATH
ENV PATH=/root/.local/bin:$PATH

WORKDIR /app

CMD ["python", "src/main.py"]

# Result: ~150MB instead of 500MB
# Efficiency: 98%