Analyze docker image size

Docker Image Size Analysis

Analyze Docker images for PHP projects to identify bloat sources and provide size reduction strategies.

Expected Size Ranges

Base Image	Minimal	Typical	Bloated
php:8.4-fpm-alpine	30-50 MB	80-120 MB	200+ MB
php:8.4-fpm (Debian)	150-200 MB	250-350 MB	500+ MB
php:8.4-cli-alpine	25-40 MB	60-100 MB	180+ MB

Common Bloat Sources

1. Build Dependencies Not Cleaned

# BLOATED: Dev packages remain in final image
RUN apk add --no-cache $PHPIZE_DEPS icu-dev libzip-dev \
    && docker-php-ext-install intl zip

# OPTIMIZED: Remove build deps after compilation
RUN apk add --no-cache --virtual .build-deps $PHPIZE_DEPS icu-dev libzip-dev \
    && docker-php-ext-install intl zip \
    && apk del .build-deps \
    && apk add --no-cache icu-libs libzip

2. Vendor with Dev Dependencies

# BLOATED: Includes dev dependencies (+30-80MB)
RUN composer install

# OPTIMIZED: No dev dependencies, optimized autoloader
RUN composer install --no-dev --no-scripts --prefer-dist --optimize-autoloader

3. Full Debian Instead of Alpine

# BLOATED: Full Debian base (~150MB base)
FROM php:8.4-fpm

# OPTIMIZED: Alpine base (~30MB base)
FROM php:8.4-fpm-alpine

4. Package Manager Cache

# BLOATED: apt cache retained (~30-50MB)
RUN apt-get update && apt-get install -y libicu-dev

# OPTIMIZED: Clean apt cache in same layer
RUN apt-get update && apt-get install -y --no-install-recommends libicu-dev \
    && rm -rf /var/lib/apt/lists/*

5. Missing .dockerignore

.git
node_modules
vendor
tests
docs
var/cache
var/log
docker-compose*.yml
.env.local
*.md
Makefile

Size Estimation by Component

Component	Typical Size	Notes
Alpine base	5-8 MB	Minimal Linux
Debian slim base	70-90 MB	More packages available
PHP runtime	25-40 MB	Core PHP binaries
PHP extensions (5-8)	10-30 MB	Depends on extensions
Composer vendor (no-dev)	20-60 MB	Depends on packages
Composer vendor (with-dev)	50-150 MB	PHPUnit, etc.
Application code	1-10 MB	Source files only
Build dependencies	50-200 MB	Must be cleaned

Multi-Stage Build (Best Practice)

FROM php:8.4-fpm-alpine AS builder
RUN apk add --no-cache --virtual .build-deps $PHPIZE_DEPS icu-dev libzip-dev \
    && docker-php-ext-install intl zip opcache \
    && apk del .build-deps
COPY composer.json composer.lock ./
RUN composer install --no-dev --prefer-dist --optimize-autoloader

FROM php:8.4-fpm-alpine AS runtime
RUN apk add --no-cache icu-libs libzip
COPY --from=builder /usr/local/lib/php/extensions/ /usr/local/lib/php/extensions/
COPY --from=builder /usr/local/etc/php/conf.d/ /usr/local/etc/php/conf.d/
COPY --from=builder /var/www/vendor /var/www/vendor
COPY . /var/www/

Grep Patterns

# Find base images used
Grep: "^FROM " --glob "**/Dockerfile*"

# Find missing cache cleanup
Grep: "apt-get install" --glob "**/Dockerfile*"
Grep: "apk add(?!.*--no-cache)" --glob "**/Dockerfile*"

# Find composer install without --no-dev
Grep: "composer install(?!.*--no-dev)" --glob "**/Dockerfile*"

# Find COPY . (copies everything)
Grep: "^COPY \. " --glob "**/Dockerfile*"

# Check for .dockerignore
Glob: "**/.dockerignore"

# Find multi-stage builds
Grep: "^FROM.*AS " --glob "**/Dockerfile*"

Reduction Impact

Strategy	Size Reduction	Effort
Alpine instead of Debian	100-150 MB	Low
Multi-stage build	50-200 MB	Medium
Remove build deps	50-200 MB	Low
--no-dev Composer	30-80 MB	Low
Clean apt/apk cache	20-50 MB	Low
.dockerignore	10-500 MB	Low

Severity Classification

Pattern	Severity	Typical Waste
No multi-stage, build deps remain	Critical	100-300 MB
No .dockerignore, .git copied	Critical	50-500 MB
Debian instead of Alpine (no reason)	Major	100-150 MB
Composer with dev dependencies	Major	30-80 MB
APT/APK cache not cleaned	Minor	20-50 MB

Output Format

### Image Size Issue: [Category]

**Severity:** Critical/Major/Minor
**Current Size:** X MB
**Estimated Savings:** Y MB
**Layer:** Dockerfile:line

**Issue:**
[Description of the bloat source]

**Current:**
```dockerfile
// Current Dockerfile instruction

Optimized:

// Optimized Dockerfile instruction

Expected Size After Fix: Before: X MB -> After: Z MB (saved Y MB)