d daedalus

Python

Building a Python App

Expected structure

daedalus detects a Python app by the presence of an entry point at the root: app.py, main.py, server.py or __main__.py.

my_app/
  app.py            ← entry point, auto-detected
  ...               ← other modules, templates, assets

Build

daedalus build ./my_app -o my_app.de

The builder:

  1. detects the python runtime and entrypoint (/app/app.py);
  2. embeds the build machine's python3 interpreter;
  3. embeds the stdlib (/usr/lib/pythonX.Y);
  4. resolves .so dependencies via the ELF analyzer (libc, etc.);
  5. compresses and assembles the .de.

Environment variables

The builder injects PYTHONUNBUFFERED=1 (real-time logs) and PYTHONDONTWRITEBYTECODE=1 by default. Your app reads its own variables normally:

import os
PORT = int(os.environ.get("PORT", "8080"))

PORT=9000 ./my_app.de

Third-party dependencies (site-packages)

daedalus automatically embeds third-party dependencies. It looks, in order:

  1. a virtualenv .venv/ or venv/ at the app root → its lib/pythonX.Y/site-packages;
  2. a vendored site-packages/ directory at the app root.
my_app/
  app.py
  .venv/                ← auto-detected, site-packages embedded
    lib/python3.12/site-packages/
      bottle.py

The builder:

  • copies site-packages to /app/site-packages in the rootfs;
  • declares PYTHONPATH=${ROOTFS}/app/site-packages (the ${ROOTFS} token is resolved by the launcher at runtime — see Launcher);
  • runs the ELF analyzer on .so files from C extensions (numpy, pillow...) to embed their system dependencies.

The example examples/bottle-web demonstrates this: it serves HTTP with bottle, a web framework not in the stdlib.

daedalus build ./examples/bottle-web -o bottle-web.de
./bottle-web.de   # → Hello from bottle, packaged by daedalus

Requirements.txt → pip install at build time

If your app has a requirements.txt with non-empty content, the builder automatically creates a temporary venv, pip-installs the dependencies, and embeds them:

daedalus build ./my_app -o my_app.de
# [daedalus] pip install: ./my_app/requirements.txt → /app/site-packages

Current limitations

  • Cross-distro portability: see Isolation — fully guaranteed at level 2 (user namespaces + pivot_root).
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