# Deployment

Deploying a **FastAPI** application is relatively easy.

## What Does Deployment Mean

To **deploy** an application means to perform the necessary steps to make it **available to the users**.

For a **web API**, it normally involves putting it in a **remote machine**, with a **server program** that provides good performance, stability, etc, so that your **users** can **access** the application efficiently and without interruptions or problems.

        {
            "detail": [
                {
                    "ctx": {"pattern": "^fixedquery$"},
                    "loc": ["query", "item-query"],
                    "msg": 'string does not match regex "^fixedquery$"',
                    "type": "value_error.str.regex",
                }
            ]
        }
    )


@needs_py39
def test_openapi_schema(client: TestClient):

        {
            "detail": [
                {
                    "ctx": {"pattern": "^fixedquery$"},
                    "loc": ["body", "q"],
                    "msg": 'string does not match regex "^fixedquery$"',
                    "type": "value_error.str.regex",
                }
            ]
        }
    )


@needs_py310
def test_openapi_schema():
    client = get_client()

```Python
async with lifespan(app):
    await do_stuff()
```

When you create a context manager or an async context manager like above, what it does is that, before entering the `with` block, it will execute the code before the `yield`, and after exiting the `with` block, it will execute the code after the `yield`.

    {!> ../../../docs_src/sql_databases/sql_app_py39/schemas.py!}
    ```

=== "Python 3.8+"

    ```Python
    {!> ../../../docs_src/sql_databases/sql_app/schemas.py!}
    ```

* `sql_app/crud.py`:

```Python
{!../../../docs_src/sql_databases/sql_app/crud.py!}
```

* `sql_app/main.py`:

=== "Python 3.9+"

    ```Python
    {!> ../../../docs_src/sql_databases/sql_app_py39/main.py!}

      id: filter
      with:
        filters: |
          docs:
            - README.md
            - docs/**
            - docs_src/**
            - requirements-docs.txt
            - pyproject.toml
            - mkdocs.yml
            - mkdocs.insiders.yml
            - .github/workflows/build-docs.yml
            - .github/workflows/deploy-docs.yml
  langs:
    needs:
      - changes
    runs-on: ubuntu-latest

logging.basicConfig(level=logging.INFO)

app = typer.Typer()

mkdocs_name = "mkdocs.yml"

missing_translation_snippet = """
{!../../../docs/missing-translation.md!}
"""

docs_path = Path("docs")
en_docs_path = Path("docs/en")
en_config_path: Path = en_docs_path / mkdocs_name
site_path = Path("site").absolute()
build_site_path = Path("site_build").absolute()


@lru_cache
def is_mkdocs_insiders() -> bool:

By default, what the method `.openapi()` does is check the property `.openapi_schema` to see if it has contents and return them.

If it doesn't, it generates them using the utility function at `fastapi.openapi.utils.get_openapi`.

And that function `get_openapi()` receives as parameters:

* `title`: The OpenAPI title, shown in the docs.
* `version`: The version of your API, e.g. `2.5.0`.

Even if your **FastAPI** application uses normal `def` functions instead of `async def`, it is still an `async` application underneath.

The `TestClient` does some magic inside to call the asynchronous FastAPI application in your normal `def` test functions, using standard pytest. But that magic doesn't work anymore when we're using it inside asynchronous functions. By running our tests asynchronously, we can no longer use the `TestClient` inside our test functions.

# OpenAPI `docs`

Utilities to handle OpenAPI automatic UI documentation, including Swagger UI (by default at `/docs`) and ReDoc (by default at `/redoc`).

::: fastapi.openapi.docs.get_swagger_ui_html

::: fastapi.openapi.docs.get_redoc_html

::: fastapi.openapi.docs.get_swagger_ui_oauth2_redirect_html