print(f"Hello {name} from Python")
```

/// tip

第二個參數是 <a href="https://docs.python.org/zh-tw/3.8/library/os.html#os.getenv" class="external-link" target="_blank">`os.getenv()`</a> 的預設回傳值。

如果沒有提供，預設值為 `None`，這裡我們提供 `"World"` 作為預設值。

///

然後你可以呼叫這個 Python 程式：

//// tab | Linux, macOS, Windows Bash

<div class="termy">

```console
// 這裡我們還沒有設定環境變數
$ python main.py

// 因為我們沒有設定環境變數，所以我們得到的是預設值

	for _, envfile := range []string{
		"/.dockerenv",
		"/run/.containerenv",
	} {
		_, err = os.Stat(envfile)
		if err == nil {
			return true
		}
	}
	if osIsNotExist(err) {
		// if none of the files are present we may be running inside
		// CRI-O, Containerd etc..
		// Fallback to our container specific ENVs if they are set.
		return env.IsSet("MINIO_ACCESS_KEY_FILE")
	}

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}
```

### Dockerfile { #dockerfile }

Ahora, en el mismo directorio del proyecto, crea un archivo `Dockerfile` con:

```{ .dockerfile .annotate }
# (1)!

		return matches[1]
	}
	return "unknown"
}

func methodNotAllowedHandler(api string) func(w http.ResponseWriter, r *http.Request) {
	return errorResponseHandler
}

// If none of the http routes match respond with appropriate errors
func errorResponseHandler(w http.ResponseWriter, r *http.Request) {
	if r.Method == http.MethodOptions {
		return
	}

			Type:        "sentence",
		},
		config.HelpKV{
			Key:         target.KafkaCompressionCodec,
			Description: "specify compression_codec of the Kafka cluster",
			Optional:    true,
			Type:        "none|snappy|gzip|lz4|zstd",
		},
		config.HelpKV{
			Key:         target.KafkaCompressionLevel,
			Description: "specify compression level of the Kafka cluster",
			Optional:    true,
			Type:        "number",
		},

		req.Header.Set(xhttp.AmzRequestID, tc.AmzReqID)
	}

	return req, nil
}

type respBodyMonitor struct {
	io.ReadCloser
	expectTimeouts  bool
	errorStatusOnce sync.Once
}

func (r *respBodyMonitor) Read(p []byte) (n int, err error) {
	n, err = r.ReadCloser.Read(p)
	r.errorStatus(err)
	return n, err
}

func (r *respBodyMonitor) Close() (err error) {

Aqui definimos a configuração `env_file` dentro da sua classe `Settings` do Pydantic e definimos o valor como o nome do arquivo dotenv que queremos usar.

### Criando o `Settings` apenas uma vez com `lru_cache` { #creating-the-settings-only-once-with-lru-cache }

Ler um arquivo do disco normalmente é uma operação custosa (lenta), então você provavelmente vai querer fazer isso apenas uma vez e depois reutilizar o mesmo objeto de configurações, em vez de lê-lo a cada requisição.

### Die `Settings` nur einmal laden mittels `lru_cache` { #creating-the-settings-only-once-with-lru-cache }

	// Is MINIO_SYNC_BOOT set?
	globalEnableSyncBoot bool

	// Contains NIC interface name used for internode communication
	globalInternodeInterface     string
	globalInternodeInterfaceOnce sync.Once

	// Set last client perf extra time (get lock, and validate)
	globalLastClientPerfExtraTime int64

	// Captures all batch jobs metrics globally
	globalBatchJobsMetrics batchJobMetrics

	}
	// A UID is added for every resource
	if len(l.lockUID) != len(rResources)*2+len(wResources)*m {
		t.Fatalf("lockUID len, got %d, want %d + %d", len(l.lockUID), len(rResources)*2, len(wResources)*m)
	}
	// RUnlock once...
	for i, name := range rResources {
		arg := dsync.LockArgs{
			UID:       rUIDs[i*2],
			Resources: []string{name},
			Source:    t.Name(),
			Owner:     "owner",
			Quorum:    &quorum,
		}