Atualizar Dockerfile / pillow dependencias

[robertatakenaka]

Pillow _imagingcms ImportError in Alpine Linux Docker containers

relacionado com scieloorg/opac-airflow#474

Summary

The packtools Docker image fails when processing images that require RGB conversion due to missing _imagingcms module in Pillow. This affects any functionality that calls Image.convert("RGB") in Alpine Linux environments.

Error Details

ImportError: cannot import name '_imagingcms' from 'PIL' 
(/usr/local/lib/python3.11/site-packages/PIL/__init__.py)

Stack trace location:

• packtools/utils.py:392 in _get_bytes()
• self._image_object.convert("RGB").save(image_file, format)

Root Cause

1. Pillow version: Current packtools uses Pillow 10.1.0 (4.11.8) / 9.1.0 (2.9.5)
2. Critical change: Since Pillow 6.0.0 (2019), .convert("RGB") automatically uses color management
3. Missing dependency: Alpine Linux Docker build lacks lcms2-dev (build-time) and lcms2 (runtime)
4. Result: Pillow compiles without _imagingcms module, causing runtime failures

Environment

• Docker base: python:3.11-alpine / python:3.7-alpine
• Packtools versions: 2.9.5, 4.11.8 (likely all versions)
• Affected operations: Image optimization, PNG/JPEG conversion

Impact

• ❌ Rancher/Kubernetes: Fails (minimal Alpine images)
• ✅ Docker Desktop macOS: Works (lcms2 often pre-installed)
• ❌ Production Alpine environments: Fails

Reproduction

# In Alpine container without lcms2
python -c "
from PIL import Image
import io
img = Image.new('RGBA', (100, 100), (255, 0, 0, 128))
img.convert('RGB')  # Triggers _imagingcms import
"

Proposed Solution

Add lcms2 dependencies to Dockerfile:

Build dependencies (temporary):

• lcms2-dev, freetype-dev, openjpeg-dev, tiff-dev, libpng-dev, zlib-dev

Runtime dependencies (permanent):

• lcms2, freetype, openjpeg, libpng, tiff, zlib

Workaround

Users can temporarily patch by adding lcms2 to their own Dockerfiles, but this should be fixed upstream to ensure consistent behavior across environments.

Related

• Similar issue affects other Alpine-based Python applications using modern Pillow versions
• Color management is essential for scientific image processing (SciELO's use case)

[robertatakenaka]

FROM python:3.11-alpine AS build
COPY . /src
RUN pip install --upgrade pip \
    && pip install wheel
RUN cd /src \
    && python setup.py bdist_wheel -d /deps

FROM python:3.11-alpine
COPY --from=build /deps/* /deps/
COPY requirements.txt .
COPY optional-requirements.txt .

# CORREÇÃO: Adicionar dependências para Pillow com suporte completo a color management
# Resolve ImportError: cannot import name '_imagingcms' from 'PIL'
RUN apk add --no-cache --virtual .build-deps \
    make gcc libxml2-dev libxslt-dev musl-dev g++ \
    lcms2-dev freetype-dev openjpeg-dev tiff-dev libpng-dev zlib-dev jpeg-dev \
    && apk add --no-cache \
    libxml2 libxslt jpeg-dev \
    lcms2 freetype openjpeg libpng tiff zlib jpeg \
    && pip install --no-cache-dir --upgrade pip setuptools \
    && pip install --no-cache-dir gunicorn \
    && pip install --no-cache-dir raven \
    && pip install --no-cache-dir -r requirements.txt \
    && pip install --no-cache-dir -r optional-requirements.txt \
    && pip install --no-index --find-links=file:///deps -U packtools[webapp] \
    && apk --purge del .build-deps \
    && rm requirements.txt \
    && rm -rf /deps

WORKDIR /app
ENV PYTHONUNBUFFERED 1
USER nobody
CMD ["gunicorn", "-w", "2", "-b", "0.0.0.0:8000", "packtools.webapp.app:app"]