!!! info
    If you are using containers, for example with Docker or Kubernetes, I'll tell you more about that in the next chapter: [FastAPI in Containers - Docker](docker.md){.internal-link target=_blank}.

    In particular, when running on **Kubernetes** you will probably **not** want to use Gunicorn and instead run **a single Uvicorn process per container**, but I'll tell you about it later in that chapter.

## Gunicorn with Uvicorn Workers

```Python
burgers = await get_burgers(2)
```

The key here is the `await`. It tells Python that it has to wait ⏸ for `get_burgers(2)` to finish doing its thing 🕙 before storing the results in `burgers`. With that, Python will know that it can go and do something else 🔀 ⏯ in the meanwhile (like receiving another request).

    The `--no-cache-dir` option tells `pip` to not save the downloaded packages locally, as that is only if `pip` was going to be run again to install the same packages, but that's not the case when working with containers.

    !!! note
        The `--no-cache-dir` is only related to `pip`, it has nothing to do with Docker or containers.

    The `--upgrade` option tells `pip` to upgrade the packages if they are already installed.

      isTlsFallback = isTlsFallback,
    )
  }

  override fun connectTcp(): ConnectResult {
    check(rawSocket == null) { "TCP already connected" }

    var success = false

    // Tell the call about the connecting call so async cancels work.
    user.addPlanToCancel(this)
    try {
      user.connectStart(route)

      connectSocket()
      success = true

# OpenAPI Webhooks

There are cases where you want to tell your API **users** that your app could call *their* app (sending a request) with some data, normally to **notify** of some type of **event**.

This means that instead of the normal process of your users sending requests to your API, it's **your API** (or your app) that could **send requests to their system** (to their API, their app).

This is normally called a **webhook**.

## Webhooks steps

```
.
└── sql_app
    ├── __init__.py
    ├── crud.py
    ├── database.py
    ├── main.py
    ├── models.py
    └── schemas.py
```

The file `__init__.py` is just an empty file, but it tells Python that `sql_app` with all its modules (Python files) is a package.

Now let's see what each file/module does.

## Install `SQLAlchemy`

First you need to install `SQLAlchemy`:

<div class="termy">

We are going to call them "**operations**" too.

#### Define a *path operation decorator*

```Python hl_lines="6"
{!../../../docs_src/first_steps/tutorial001.py!}
```

The `@app.get("/")` tells **FastAPI** that the function right below is in charge of handling requests that go to:

* the path `/`
* using a <abbr title="an HTTP GET method"><code>get</code> operation</abbr>

!!! info "`@decorator` Info"

I'll tell you a bit more about these **concepts** here, and that would hopefully give you the **intuition** you would need to decide how to deploy your API in very different environments, possibly even in **future** ones that don't exist yet.

   * requires us to have a DNS address for both hosts, which only happens after route planning. We
   * can't coalesce connections that use a proxy, since proxies don't tell us the origin server's IP
   * address.
   */
  private fun routeMatchesAny(candidates: List<Route>): Boolean {
    return candidates.any {
      it.proxy.type() == Proxy.Type.DIRECT &&

        type = TYPE_PING,
        flags = if (ack) FLAG_ACK else FLAG_NONE,
      )
      sink.writeInt(payload1)
      sink.writeInt(payload2)
      sink.flush()
    }
  }

  /**
   * Tell the peer to stop creating streams and that we last processed `lastGoodStreamId`, or zero
   * if no streams were processed.
   *
   * @param lastGoodStreamId the last stream ID processed, or zero if no streams were processed.