Python

This example shows how to migrate a Python application to Docker Hardened Images.

The following examples show Dockerfiles before and after migration to Docker Hardened Images. Each example includes five variations:

• Before (Ubuntu): A sample Dockerfile using Ubuntu-based images, before migrating to DHI
• Before (Wolfi): A sample Dockerfile using Wolfi distribution images, before migrating to DHI
• Before (DOI): A sample Dockerfile using Docker Official Images, before migrating to DHI
• After (multi-stage): A sample Dockerfile after migrating to DHI with multi-stage builds (recommended for minimal, secure images)
• After (single-stage): A sample Dockerfile after migrating to DHI with single-stage builds (simpler but results in a larger image with a broader attack surface)

[!NOTE]

Multi-stage builds are recommended for most use cases. Single-stage builds are supported for simplicity, but come with tradeoffs in size and security.

You must authenticate to dhi.io before you can pull Docker Hardened Images. Use your Docker ID credentials (the same username and password you use for Docker Hub). If you don't have a Docker account, create one for free.

Run docker login dhi.io to authenticate.

{{< tabs >}} {{< tab name="Before (Ubuntu)" >}}

#syntax=docker/dockerfile:1

FROM ubuntu:24.04 AS builder

RUN apt-get update && apt-get install -y python3 python3-pip python3-venv --no-install-recommends && rm -rf /var/lib/apt/lists/*

ENV LANG=C.UTF-8
ENV PYTHONDONTWRITEBYTECODE=1
ENV PYTHONUNBUFFERED=1
ENV PATH="/app/venv/bin:$PATH"

WORKDIR /app

RUN python3 -m venv /app/venv
COPY requirements.txt .

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

FROM ubuntu:24.04

RUN apt-get update && apt-get install -y python3 --no-install-recommends && rm -rf /var/lib/apt/lists/*

WORKDIR /app

ENV PYTHONUNBUFFERED=1
ENV PATH="/app/venv/bin:$PATH"

COPY app.py ./
COPY --from=builder /app/venv /app/venv

ENTRYPOINT [ "python3", "/app/app.py" ]

{{< /tab >}} {{< tab name="Before (Wolfi)" >}}

#syntax=docker/dockerfile:1

FROM cgr.dev/chainguard/python:latest-dev AS builder

ENV LANG=C.UTF-8
ENV PYTHONDONTWRITEBYTECODE=1
ENV PYTHONUNBUFFERED=1
ENV PATH="/app/venv/bin:$PATH"

WORKDIR /app

RUN python -m venv /app/venv
COPY requirements.txt .

# Install any additional packages if needed using apk
# RUN apk add --no-cache gcc musl-dev

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

FROM cgr.dev/chainguard/python:latest

WORKDIR /app

ENV PYTHONUNBUFFERED=1
ENV PATH="/app/venv/bin:$PATH"

COPY app.py ./
COPY --from=builder /app/venv /app/venv

ENTRYPOINT [ "python", "/app/app.py" ]

{{< /tab >}} {{< tab name="Before (DOI)" >}}

#syntax=docker/dockerfile:1

FROM python:latest AS builder

ENV LANG=C.UTF-8
ENV PYTHONDONTWRITEBYTECODE=1
ENV PYTHONUNBUFFERED=1
ENV PATH="/app/venv/bin:$PATH"

WORKDIR /app

RUN python -m venv /app/venv
COPY requirements.txt .

# Install any additional packages if needed using apt
# RUN apt-get update && apt-get install -y gcc && rm -rf /var/lib/apt/lists/*

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

FROM python:latest

WORKDIR /app

ENV PYTHONUNBUFFERED=1
ENV PATH="/app/venv/bin:$PATH"

COPY app.py ./
COPY --from=builder /app/venv /app/venv

ENTRYPOINT [ "python", "/app/app.py" ]

{{< /tab >}} {{< tab name="After (multi-stage)" >}}

#syntax=docker/dockerfile:1

# === Build stage: Install dependencies and create virtual environment ===
FROM dhi.io/python:3.13-alpine3.23-dev AS builder

ENV LANG=C.UTF-8
ENV PYTHONDONTWRITEBYTECODE=1
ENV PYTHONUNBUFFERED=1
ENV PATH="/app/venv/bin:$PATH"

WORKDIR /app

RUN python -m venv /app/venv
COPY requirements.txt .

# Install any additional packages if needed using apk
# RUN apk add --no-cache gcc musl-dev

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

# === Final stage: Create minimal runtime image ===
FROM dhi.io/python:3.13-alpine3.23

WORKDIR /app

ENV PYTHONUNBUFFERED=1
ENV PATH="/app/venv/bin:$PATH"

COPY app.py ./
COPY --from=builder /app/venv /app/venv

ENTRYPOINT [ "python", "/app/app.py" ]

{{< /tab >}} {{< tab name="After (single-stage)" >}}

#syntax=docker/dockerfile:1

FROM dhi.io/python:3.13-alpine3.23-dev

ENV LANG=C.UTF-8
ENV PYTHONDONTWRITEBYTECODE=1
ENV PYTHONUNBUFFERED=1
ENV PATH="/app/venv/bin:$PATH"

WORKDIR /app

RUN python -m venv /app/venv
COPY requirements.txt .

# Install any additional packages if needed using apk
# RUN apk add --no-cache gcc musl-dev

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

COPY app.py ./

ENTRYPOINT [ "python", "/app/app.py" ]

{{< /tab >}} {{< /tabs >}}