```

In the dependency override we set a new value for the `admin_email` when creating the new `Settings` object, and then we return that new object.

Then we can test that it is used.

## Reading a `.env` file

If you have many settings that possibly change a lot, maybe in different environments, it might be useful to put them on a file and then read them from it as if they were environment variables.

if [[ "${TFCI_MACOS_UPGRADE_PYENV_ENABLE}" == 1 ]]; then
  # The TFCI Mac VM image seems to have uncommitted local changes to the Pyenv
  # repository so we have to discard them and reset the working directory before
  # we can pull in the latest changes.
  cd /Users/kbuilder/.pyenv/ && git reset --hard HEAD && git pull && cd -
fi

# "TFCI_MACOS_PYENV_INSTALL_ENABLE" controls whether to use Pyenv to install

To achieve this, the backend must have a list of "allowed origins".

In this case, it would have to include `http://localhost:8080` for the frontend to work correctly.

## Wildcards

nothing available, we need to hold that thread until either the bytes arrive, the stream is closed, or a timeout elapses. If we get bytes but there's nobody asking for them, we buffer them. We don't consider bytes as delivered for flow control until they're consumed by the application.

Consider an application streaming a video over http/2. Perhaps the user pauses the video and the application stops reading bytes from this stream. The buffer will fill up, and flow control prevents the server...

You can also declare the `Response` parameter in dependencies, and set cookies (and headers) in them.

## Return a `Response` directly

You can also create cookies when returning a `Response` directly in your code.

that *temporal* response to extract the status code (also cookies and headers), and will put them in the final response that contains the value you returned, filtered by any `response_model`.

You can also declare the `Response` parameter in dependencies, and set the status code in them. But keep in mind that the last one to be set will win....

# Copyright 2023 The TensorFlow Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,

- ⚡ [**FastAPI**](https://fastapi.tiangolo.com) for the Python backend API.
    - 🧰 [SQLModel](https://sqlmodel.tiangolo.com) for the Python SQL database interactions (ORM).
    - 🔍 [Pydantic](https://docs.pydantic.dev), used by FastAPI, for the data validation and settings management.
    - 💾 [PostgreSQL](https://www.postgresql.org) as the SQL database.
- 🚀 [React](https://react.dev) for the frontend.

```Python hl_lines="8"
{!../../../docs_src/custom_docs_ui/tutorial001.py!}
```

### Include the custom docs

Now you can create the *path operations* for the custom docs.

You can re-use FastAPI's internal functions to create the HTML pages for the docs, and pass them the needed arguments:

- Temporary credentials do not need to be stored with the application but are generated dynamically and provided to the application when requested. When (or even before) the temporary credentials expire, the application can request new credentials.

Following are advantages for using temporary credentials:

- Eliminates the need to embed long-term credentials with an application.