📝 Add documentation for self-serving static Swagger UI (#112) (#557)

docs/src/extending_openapi/tutorial002.py

@@ -0,0 +1,41 @@
+from fastapi import FastAPI
+from fastapi.openapi.docs import (
+    get_redoc_html,
+    get_swagger_ui_html,
+    get_swagger_ui_oauth2_redirect_html,
+)
+from starlette.staticfiles import StaticFiles
+
+app = FastAPI(docs_url=None, redoc_url=None)
+
+app.mount("/static", StaticFiles(directory="static"), name="static")
+
+
+@app.get("/docs", include_in_schema=False)
+async def custom_swagger_ui_html():
+    return get_swagger_ui_html(
+        openapi_url=app.openapi_url,
+        title=app.title + " - Swagger UI",
+        oauth2_redirect_url=app.swagger_ui_oauth2_redirect_url,
+        swagger_js_url="/static/swagger-ui-bundle.js",
+        swagger_css_url="/static/swagger-ui.css",
+    )
+
+
+@app.get(app.swagger_ui_oauth2_redirect_url, include_in_schema=False)
+async def swagger_ui_redirect():
+    return get_swagger_ui_oauth2_redirect_html()
+
+
+@app.get("/redoc", include_in_schema=False)
+async def redoc_html():
+    return get_redoc_html(
+        openapi_url=app.openapi_url,
+        title=app.title + " - ReDoc",
+        redoc_js_url="/static/redoc.standalone.js",
+    )
+
+
+@app.get("/users/{username}")
+async def read_user(username: str):
+    return {"message": f"Hello {username}"}

docs/tutorial/extending-openapi.md

@@ -88,3 +88,156 @@ Now you can replace the `.openapi()` method with your new function.
 Once you go to <a href="http://127.0.0.1:8000/redoc" target="_blank">http://127.0.0.1:8000/redoc</a> you will see that you are using your custom logo (in this example, **FastAPI**'s logo):
 
 <img src="/img/tutorial/extending-openapi/image01.png">
+
+## Self-hosting JavaScript and CSS for docs
+
+The API docs use **Swagger UI** and **ReDoc**, and each of those need some JavaScript and CSS files.
+
+By default, those files are served from a <abbr title="Content Delivery Network: A service, normally composed of several servers, that provides static files, like JavaScript and CSS. It's commonly used to serve those files from the server closer to the client, improving performance.">CDN</abbr>.
+
+But it's possible to customize it, you can set a specific CDN, or serve the files yourself.
+
+That's useful, for example, if you need your app to keep working even while offline, without open Internet access, or in a local network.
+
+Here you'll see how to serve those files yourself, in the same FastAPI app, and configure the docs to use them.
+
+### Project file structure
+
+Let's say your project file structure looks like this:
+
+```
+.
+├── app
+│   ├── __init__.py
+│   ├── main.py
+```
+
+Now create a directory to store those static files.
+
+Your new file structure could look like this:
+
+```
+.
+├── app
+│   ├── __init__.py
+│   ├── main.py
+└── static/
+```
+
+### Download the files
+
+Download the static files needed for the docs and put them on that `static/` directory.
+
+You can probably right-click each link and select an option similar to `Save link as...`.
+
+**Swagger UI** uses the files:
+
+* <a href="https://cdn.jsdelivr.net/npm/swagger-ui-dist@3/swagger-ui-bundle.js">`swagger-ui-bundle.js`</a>
+* <a href="https://cdn.jsdelivr.net/npm/swagger-ui-dist@3/swagger-ui.css" target="_blank">`swagger-ui.css`</a>
+
+And **ReDoc** uses the file:
+
+* <a href="https://cdn.jsdelivr.net/npm/redoc@next/bundles/redoc.standalone.js" target="_blank">`redoc.standalone.js`</a>
+
+After that, your file structure could look like:
+
+```
+.
+├── app
+│   ├── __init__.py
+│   ├── main.py
+└── static
+    ├── redoc.standalone.js
+    ├── swagger-ui-bundle.js
+    └── swagger-ui.css
+```
+
+### Install `aiofiles`
+
+Now you need to install `aiofiles`:
+
+```bash
+pip install aiofiles
+```
+
+### Serve the static files
+
+* Import `StaticFiles` from Starlette.
+* "Mount" it the same way you would <a href="https://fastapi.tiangolo.com/tutorial/sub-applications-proxy/" target="_blank">mount a Sub-Application</a>.
+
+```Python hl_lines="7 11"
+{!./src/extending_openapi/tutorial002.py!}
+```
+
+### Test the static files
+
+Start your application and go to <a href="http://127.0.0.1:8000/static/redoc.standalone.js" target="_blank">http://127.0.0.1:8000/static/redoc.standalone.js</a>.
+
+You should see a very long JavaScript file for **ReDoc**.
+
+It could start with something like:
+
+```JavaScript
+/*!
+ * ReDoc - OpenAPI/Swagger-generated API Reference Documentation
+ * -------------------------------------------------------------
+ *   Version: "2.0.0-rc.18"
+ *   Repo: https://github.com/Redocly/redoc
+ */
+!function(e,t){"object"==typeof exports&&"object"==typeof m
+
+...
+```
+
+That confirms that you are being able to serve static files from your app, and that you placed the static files for the docs in the correct place.
+
+Now we can configure the app to use those static files for the docs.
+
+### Disable the automatic docs
+
+The first step is to disable the automatic docs, as those use the CDN by default.
+
+To disable them, set their URLs to `None` when creating your `FastAPI` app:
+
+```Python hl_lines="9"
+{!./src/extending_openapi/tutorial002.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:
+
+* `openapi_url`: the URL where the HTML page for the docs can get the OpenAPI schema for your API. You can use here the attribute `app.openapi_url`.
+* `title`: the title of your API.
+* `oauth2_redirect_url`: you can use `app.swagger_ui_oauth2_redirect_url` here to use the default.
+* `swagger_js_url`: the URL where the HTML for your Swagger UI docs can get the **JavaScript** file. This is the one that your own app is now serving.
+* `swagger_css_url`: the URL where the HTML for your Swagger UI docs can get the **CSS** file. This is the one that your own app is now serving.
+
+And similarly for ReDoc...
+
+```Python hl_lines="2 3 4 5 6   14 15 16 17 18 19 20 21 22    25 26 27   30 31 32 33 34 35 36"
+{!./src/extending_openapi/tutorial002.py!}
+```
+
+!!! tip
+    The *path operation* for `swagger_ui_redirect` is a helper for when you use OAuth2.
+
+    If you integrate your API with an OAuth2 provider, you will be able to authenticate and come back to the API docs with the acquired credentials. And interact with it using the real OAuth2 authentication.
+
+    Swagger UI will handle it behind the scenes for you, but it needs this "redirect" helper.
+
+### Create a *path operation* to test it
+
+Now, to be able to test that everything works, create a path operation:
+
+```Python hl_lines="39 40 41"
+{!./src/extending_openapi/tutorial002.py!}
+```
+
+### Test it
+
+Now, you should be able to disconnect your WiFi, go to your docs at <a href="http://127.0.0.1:8000/docs" target="_blank">http://127.0.0.1:8000/docs</a>, and reload the page.
+
+And even without Internet, you would be able to see the docs for your API and interact with it.

tests/test_tutorial/test_extending_openapi/test_tutorial002.py

@@ -0,0 +1,42 @@
+import os
+from pathlib import Path
+
+import pytest
+from starlette.testclient import TestClient
+
+
+@pytest.fixture(scope="module")
+def client():
+    static_dir: Path = Path(os.getcwd()) / "static"
+    print(static_dir)
+    static_dir.mkdir(exist_ok=True)
+    from extending_openapi.tutorial002 import app
+
+    with TestClient(app) as client:
+        yield client
+    static_dir.rmdir()
+
+
+def test_swagger_ui_html(client: TestClient):
+    response = client.get("/docs")
+    assert response.status_code == 200
+    assert "/static/swagger-ui-bundle.js" in response.text
+    assert "/static/swagger-ui.css" in response.text
+
+
+def test_swagger_ui_oauth2_redirect_html(client: TestClient):
+    response = client.get("/docs/oauth2-redirect")
+    assert response.status_code == 200
+    assert "window.opener.swaggerUIRedirectOauth2" in response.text
+
+
+def test_redoc_html(client: TestClient):
+    response = client.get("/redoc")
+    assert response.status_code == 200
+    assert "/static/redoc.standalone.js" in response.text
+
+
+def test_api(client: TestClient):
+    response = client.get("/users/john")
+    assert response.status_code == 200
+    assert response.json()["message"] == "Hello john"