A NestJS-style, batteries-included web framework for Python, built on top of FastAPI.

Austial

Austial gives Python the exact developer experience of NestJS: decorator-driven modules/controllers/providers, real constructor-based dependency injection, the full request lifecycle (guards, pipes, interceptors, exception filters, middleware), a config layer, a database layer, Terminus-style health checks, a testing module -- and a CLI so you can scaffold new projects and artifacts the same way nest new/nest generate do.

This repository (austial-py) is the framework itself -- an installable library, no bundled sample app. To see it in action, scaffold a new project with the CLI (see Quickstart below); that generated project is the "hello world" app, kept separate from the framework's own source tree.

Why

FastAPI is a fantastic ASGI toolkit, but it doesn't prescribe an application architecture. Austial is opinionated on top of FastAPI the way Nest is opinionated on top of Express/Fastify: modules own controllers and providers, providers get dependency-injected by type, and the request pipeline (guard → pipe → interceptor → handler → filter) is a first-class concept instead of something you hand-roll with dependencies everywhere.

Architecture at a glance

A note on file names

Nest names files with dots (health.controller.ts) because Node resolves modules by explicit relative path strings. Python's import a.b instead resolves a as a package and b as a submodule -- a literal file health.controller.py isn't importable via a normal import statement. So Austial uses underscore suffixes instead: health_controller.py, health_service.py, health_module.py, health_dto.py. The directory layout still mirrors Nest 1:1 -- one folder per feature under src/modules/.

Quickstart

Austial is published on PyPI -- install the CLI and scaffold a new project:

uv tool install austial                 # or: pipx install austial / pip install austial
austial new my-app                      # scaffold a new project
cd my-app
uv sync
cp .env.example .env
uv run austial serve                    # http://localhost:8000, auto-reload

austial new scaffolds a small health-check "hello world" app -- GET /, GET /health, GET /health/protected, /docs (Swagger UI) -- see Using the CLI below for the full generator reference.

Developing Austial itself

git clone https://github.com/austial/austial-py
cd austial-py
uv sync --all-extras
uv run pytest

Linting, type-checking & pre-commit hooks

uv run ruff check .           # lint
uv run ruff format .          # format
uv run mypy austial tests     # type-check

uv run pre-commit install --hook-type pre-commit --hook-type pre-push
uv run pre-commit run --all-files   # run every hook once, on demand

Once installed, git commit runs formatting/linting/type-checks automatically, and git push also runs the test suite -- mirroring a typical Nest project's husky + lint-staged setup. Projects scaffolded with austial new get the same .pre-commit-config.yaml out of the box.

Using the CLI

austial new scaffolds a brand-new project exactly like nest new:

uv run austial new my-app
cd my-app
uv sync
cp .env.example .env
uv run austial serve

New projects depend on the published austial package from PyPI by default. If you're developing the framework itself, point new projects at your local checkout instead with --link: austial new my-app --link /path/to/austial-py -- this adds an editable [tool.uv.sources] entry so uv sync resolves austial from your local checkout rather than PyPI.

austial generate (alias austial g) adds artifacts to an existing project, patching src/app_module.py's imports/imports=[...] array automatically -- just like nest g:

uv run austial generate module cats        # src/modules/cats/cats_module.py
uv run austial generate controller cats    # src/modules/cats/cats_controller.py
uv run austial generate service cats       # src/modules/cats/cats_service.py
uv run austial generate resource cats      # module + full CRUD controller/service/dto/entity
uv run austial g resource cats             # same as above, short alias

Repository layout

austial-py/
├── pyproject.toml          # package "austial", console-script entry point
├── LICENSE                  # MIT
├── assets/                   # logo.svg (+ logo-dark.svg for dark mode) / icon.svg / apple-icon.png
├── austial/                 # the framework (installable library) -- this *is* the package
│   ├── common/               # decorators, guards, interceptors, pipes, filters,
│   │                         # middleware, exceptions, logger
│   ├── core/                  # metadata/reflector, DI container, router builder,
│   │                         # AustialFactory / AustialApplication
│   ├── config/                 # ConfigModule / ConfigService
│   ├── database/                # DatabaseModule (SQLAlchemy async)
│   ├── terminus/                 # HealthCheckService + health indicators
│   ├── testing/                   # Test.create_testing_module(...)
│   └── cli/                        # `austial new` / `generate` / `serve` + templates
└── tests/                    # tests for the framework itself -- no sample app needed;
    ├── unit/                   # test modules/controllers are defined inline per test file
    └── e2e/

There's deliberately no src/ here -- that's what austial new generates for your project, kept out of the framework's own repo. Test files use Nest's *.spec.ts naming convention (*_spec.py here); pyproject.toml's [tool.pytest.ini_options] is configured to discover them.

Request lifecycle

Every route runs through the same pipeline Nest uses:

guards -> pipes -> interceptors (wrapping) -> handler -> exception filters

from austial import Controller, Get, UseGuards, UseInterceptors
from austial.common.interceptors import TransformInterceptor

from .api_key_guard import ApiKeyGuard


@Controller("cats")
class CatsController:
    @Get(":id")
    @UseGuards(ApiKeyGuard)
    @UseInterceptors(TransformInterceptor())
    async def find_one(self, id: int):
        ...

Note path params use Nest's :id syntax (translated to FastAPI's {id} under the hood), so route strings read exactly like their Nest counterparts.

Releasing

Pushing a v*.*.* tag triggers .github/workflows/publish.yml, which re-runs the lint/type-check/test gate, builds the sdist + wheel with uv build, publishes them to PyPI via trusted publishing (no API token stored as a secret), and attaches the built artifacts to a GitHub release:

# bump the version in pyproject.toml first, then:
git commit -am "Bump to vX.Y.Z"
git tag -a vX.Y.Z -m "vX.Y.Z - ..."
git push origin main
git push origin vX.Y.Z

One-time setup: on PyPI's publishing settings for the project, add austial-py's publish.yml workflow (environment pypi) as a trusted publisher.

License

MIT