conformance:v1.28.9](https://console.cloud.google.com/artifacts/docker/k8s-artifacts-prod/southamerica-east1/images/conformance) | [amd64](https://console.cloud.google.com/artifacts/docker/k8s-artifacts-prod/southamerica-east1/images/conformance-amd64), [arm64](https://console.cloud.google.com/artifacts/docker/k8s-artifacts-prod/southamerica-east1/images/conformance-arm64), [ppc64le](https://console.cloud.google.com/artifacts/docker/k8s-artifacts-prod/southamerica-east1/images/conformance-ppc64le),...

因此， （运行在浏览器中的）前端会尝试访问 `/openapi.json`，但没有办法获取 OpenAPI 概图。

这是因为应用使用了以 `/api/v1` 为路径前缀的代理，前端要从 `/api/v1/openapi.json`  中提取 OpenAPI 概图。

```mermaid
graph LR

browser("Browser")
proxy["Proxy on http://0.0.0.0:9999/api/v1/app"]
server["Server on http://127.0.0.1:8000/app"]

browser --> proxy
proxy --> server
```

!!! tip "提示"

    IP `0.0.0.0` 常用于指程序监听本机或服务器上的所有有效 IP。

Então, vamos rever de um ponto de vista simplificado:

* O usuário digita o `username` e a `senha` no frontend e aperta `Enter`.
* O frontend (rodando no browser do usuário) manda o `username` e a `senha` para uma URL específica na sua API (declarada com `tokenUrl="token"`).
* A API checa aquele `username` e `senha`, e responde com um "token" (nós não implementamos nada disso ainda).

↩️ 👥 ✔️ 🗳 ⏮️ ➡ 🔡 `/api/v1` 👆 📱, 🕸 💪 ☕ 🗄 🔗 `/api/v1/openapi.json`.

```mermaid
graph LR

browser("Browser")
proxy["Proxy on http://0.0.0.0:9999/api/v1/app"]
server["Server on http://127.0.0.1:8000/app"]

browser --> proxy
proxy --> server
```

!!! tip
    📢 `0.0.0.0` 🛎 ⚙️ ⛓ 👈 📋 👂 🔛 🌐 📢 💪 👈 🎰/💽.

<img src="/img/tutorial/sub-applications/image02.png">

If you try interacting with any of the two user interfaces, they will work correctly, because the browser will be able to talk to each specific app or sub-app.

### Technical Details: `root_path`

	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		read := r.Method == http.MethodGet || r.Method == http.MethodHead
		// Re-direction is handled specifically for browser requests.
		if !guessIsHealthCheckReq(r) && guessIsBrowserReq(r) && read && globalBrowserRedirect {
			// Fetch the redirect location if any.
			if u := getRedirectLocation(r); u != nil {
				// Employ a temporary re-direct.

onformance:v1.27.13](https://console.cloud.google.com/artifacts/docker/k8s-artifacts-prod/southamerica-east1/images/conformance) | [amd64](https://console.cloud.google.com/artifacts/docker/k8s-artifacts-prod/southamerica-east1/images/conformance-amd64), [arm64](https://console.cloud.google.com/artifacts/docker/k8s-artifacts-prod/southamerica-east1/images/conformance-arm64), [ppc64le](https://console.cloud.google.com/artifacts/docker/k8s-artifacts-prod/southamerica-east1/images/conformance-ppc64le),...

```console
$ gunicorn main:app --workers 4 --worker-class uvicorn.workers.UvicornWorker --bind 0.0.0.0:80

[19499] [INFO] Starting gunicorn 20.1.0
[19499] [INFO] Listening at: http://0.0.0.0:80 (19499)
[19499] [INFO] Using worker: uvicorn.workers.UvicornWorker
[19511] [INFO] Booting worker with pid: 19511
[19513] [INFO] Booting worker with pid: 19513
[19514] [INFO] Booting worker with pid: 19514
[19515] [INFO] Booting worker with pid: 19515

    "crossVersionTests": false
  },
  {
    "name": "worker-processes",
    "path": "platforms/core-execution/worker-processes",
    "unitTests": true,
    "functionalTests": false,
    "crossVersionTests": false
  },
  {
    "name": "worker-services",
    "path": "platforms/core-runtime/worker-services",
    "unitTests": false,
    "functionalTests": false,

            alternatingKeysAndValues[previousKeyIndex ^ 1] = value;
            continue entries;
          }
        }
        if (outI < i) { // if outI == i don't bother writing the values back where they came from
          alternatingKeysAndValues[outKeyIndex] = key;
          alternatingKeysAndValues[outKeyIndex ^ 1] = value;
        }
        outI++;
      }