**FastAPI** will create the object of type `BackgroundTasks` for you and pass it as that parameter.

## Create a task function

Create a function to be run as the background task.

It is just a standard function that can receive parameters.

It can be an `async def` or normal `def` function, **FastAPI** will know how to handle it correctly.

In this case, the task function will write to a file (simulating sending an email).

import static java.util.Objects.requireNonNull;

import com.google.common.collect.ImmutableSet;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;

/**
 * Standard implementation of {@link Network} that supports the options supplied by {@link
 * NetworkBuilder}.
 *
 * <p>This class maintains a map of nodes to {@link NetworkConnections}. This class also maintains a

import static java.util.Objects.requireNonNull;

import com.google.common.collect.ImmutableSet;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;

/**
 * Standard implementation of {@link Network} that supports the options supplied by {@link
 * NetworkBuilder}.
 *
 * <p>This class maintains a map of nodes to {@link NetworkConnections}. This class also maintains a

# AssumeRoleWithWebIdentity [![Slack](https://slack.min.io/slack?type=svg)](https://slack.min.io)

## Introduction

MinIO supports the standard AssumeRoleWithWebIdentity STS API to enable integration with OIDC/OpenID based identity provider environments. This allows the generation of temporary credentials with pre-defined access policies for applications/users to interact with MinIO object storage.

/**
 * Low-level, high-performance utility methods related to the {@linkplain Charsets#UTF_8 UTF-8}
 * character encoding. UTF-8 is defined in section D92 of <a
 * href="http://www.unicode.org/versions/Unicode6.2.0/ch03.pdf">The Unicode Standard Core
 * Specification, Chapter 3</a>.
 *
 * <p>The variant of UTF-8 implemented by this class is the restricted definition of UTF-8
 * introduced in Unicode 3.1. One implication of this is that it rejects <a

そして、Gunicorn互換の**Uvicornワーカー**クラスが、FastAPIが使えるように、Gunicornから送られてきたデータをASGI標準に変換する役割を担います。

## GunicornとUvicornをインストールする

<div class="termy">

```console
$ pip install "uvicorn[standard]" gunicorn

---> 100%
```

</div>

これによりUvicornと（高性能を得るための）標準（`standard`）の追加パッケージとGunicornの両方がインストールされます。

## UvicornのワーカーとともにGunicornを実行する

Gunicornを以下のように起動させることができます:

<div class="termy">

```console

 * default} methods. Instead, it inherits their default implementations. When those implementations
 * invoke methods, they invoke methods on the {@code ForwardingList}.
 *
 * <p>The {@code standard} methods and any collection views they return are not guaranteed to be
 * thread-safe, even when all of the methods that they depend on are thread-safe.
 *
 * @author Mike Bostock
 * @author Louis Wasserman
 * @since 2.0

        print(statsDetails['BytesProcessed'])
```

## 4. Run the Program

Upload a sample dataset to MinIO using the following commands.

```sh
curl "https://population.un.org/wpp/Download/Files/1_Indicators%20(Standard)/CSV_FILES/WPP2019_TotalPopulationBySex.csv" > TotalPopulation.csv
mc mb myminio/mycsvbucket
gzip TotalPopulation.csv
mc cp TotalPopulation.csv.gz myminio/mycsvbucket/sampledata/
```

This is not a limitation of **FastAPI**, it's part of the HTTP protocol.

///

## Optional File Upload

You can make a file optional by using standard type annotations and setting a default value of `None`:

//// tab | Python 3.10+

```Python hl_lines="9  17"
{!> ../../docs_src/request_files/tutorial001_02_an_py310.py!}
```

////

   *
   * <p>Any {@linkplain OpenOption open options} provided are used when opening streams to the file
   * and may affect the behavior of the returned source and the streams it provides. See {@link
   * StandardOpenOption} for the standard options that may be provided. Providing no options is
   * equivalent to providing the {@link StandardOpenOption#READ READ} option.
   */
  public static ByteSource asByteSource(Path path, OpenOption... options) {