Dockerfile Breakdown: Headless RAG Pipeline with OCR and Cron

This Dockerfile sets up a scheduled document processing pipeline using Python 3.10, Tesseract for OCR, and cron for scheduled jobs. It is optimized to run uploader.py nightly, processing documents from a ./docs folder.

1. Base Image

FROM python:3.10-slim

• Uses a minimal, official Python 3.10 image.

• Reduces image size and attack surface.

2. Environment Configuration

ENV PYTHONDONTWRITEBYTECODE=1 \
    PYTHONUNBUFFERED=1 \
    TZ=America/New_York

• PYTHONDONTWRITEBYTECODE=1: prevents writing .pyc files.

• PYTHONUNBUFFERED=1: ensures output is logged in real time.

• TZ=America/New_York: sets the correct timezone for scheduling tasks.

3. Working Directory

WORKDIR /app

• All operations are conducted in /app inside the container.

You can inspect it with:

docker exec -it <container_id_or_name> sh
cd /app

4. Install System Dependencies

RUN apt-get update && apt-get install -y \
    build-essential \
    poppler-utils \
    tesseract-ocr \
    ocrmypdf \
    cron \
    curl \
    tzdata \
 && rm -rf /var/lib/apt/lists/*

• build-essential: required to build Python packages.

• poppler-utils: extracts content from PDF files.

• tesseract-ocr and ocrmypdf: support OCR on image-based or scanned PDFs.

• cron: runs scheduled jobs.

• curl: useful for network-based operations.

• tzdata: sets timezone correctly.

5. Install Python Dependencies

COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt

• Installs Python packages listed in requirements.txt.

• --no-cache-dir avoids unnecessary cache layers.

6. Copy Application Source

COPY . .

• Copies all application code into the container under /app.

7. Configure Crontab

COPY crontab.txt /etc/cron.d/uploader-cron
RUN chmod 0644 /etc/cron.d/uploader-cron && \
    crontab /etc/cron.d/uploader-cron

• Adds a cron schedule (typically for uploader.py) from crontab.txt.

• Registers it into the system crontab.

Example of crontab.txt:

0 2 * * * root python /app/uploader.py >> /app/logs/cron.log 2>&1

8. Start Cron in Foreground

CMD ["cron", "-f"]

• Keeps the container alive by running cron in the foreground.