title	toc	weight	nd-docs
FastAPI	true	900	DOCS-1738

To run apps built with the FastAPI web framework using Unit:

Install [Unit]({{< relref "/unit/installation.md#installation-precomp-pkgs" >}}) with a Python 3.6+ language module.

Create a virtual environment to install FastAPI's PIP package, for instance:

$ cd /path/to/app/  # Path to the application directory; use a real path in your configuration
$ python --version  # Make sure your virtual environment version matches the module version
      Python X.Y.Z  # Major version, minor version, and revision number
$ python -m venv venv  # Arbitrary name of the virtual environment
$ source venv/bin/activate  # Name of the virtual environment from the previous command
$ pip install fastapi
$ deactivate

{{< call-out "warning" >}} Create your virtual environment with a Python version that matches the language module from Step 1 up to the minor number (X.Y in this example). Also, the app type in Step 5 must [resolve]({{< relref "/unit/configuration.md#configuration-apps-common" >}}) to a similarly matching version; Unit doesn't infer it from the environment. {{< /call-out >}}

Let's try a version of a tutorial app, saving it as /path/to/app/asgi.py:
```
from fastapi import FastAPI

app = FastAPI()

@app.get("/")
async def root():
    return {"message": "Hello, World!"}
```
{{< call-out "note" >}} For something more true-to-life, try the RealWorld example app; just install all its dependencies in the same virtual environment where you've installed FastAPI and add the app's environment {ref}variables <configuration-apps-common> like DB_CONNECTION or SECRET_KEY directly to the app configuration in Unit instead of the .env file. {{< /call-out >}}
Change ownership:

{{< include "unit/howto_change_ownership.md" >}}

Next, [prepare]({{< relref "/unit/configuration.md#configuration-python" >}}) the FastAPI configuration for Unit (use real values for type, home, and path):

{
   "listeners": {
      "*:80": {
         "pass": "applications/fastapi"
      }
   },
   "applications": {
      "fastapi": {
         "type": "python 3.Y",
         "type_comment": "Must match language module version and virtual environment version",
         "path": "/path/to/app/",
         "path_comment": "Path to the ASGI module",
         "home": "/path/to/app/venv/",
         "home_comment": "Path to the virtual environment, if any",
         "module": "asgi",
         "module_comment": "ASGI module filename with extension omitted",
         "callable": "app",
         "callable_comment": "Name of the callable in the module to run"
      }
   }
}

Upload the updated configuration.

{{< include "unit/howto_upload_config.md" >}}

After a successful update, your app should be available on the listener’s IP address and port:
```
curl http://localhost

      Hello, World!
```
Alternatively, try FastAPI's nifty self-documenting features:

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