在许多情况下，您的应用程序可能需要一些外部设置或配置，例如密钥、数据库凭据、电子邮件服务的凭据等等。

这些设置中的大多数是可变的（可以更改的），比如数据库的 URL。而且许多设置可能是敏感的，比如密钥。

因此，通常会将它们提供为由应用程序读取的环境变量。

## 环境变量

/// tip

如果您已经知道什么是"环境变量"以及如何使用它们，请随意跳到下面的下一节。

///

环境变量（也称为"env var"）是一种存在于 Python 代码之外、存在于操作系统中的变量，可以被您的 Python 代码（或其他程序）读取。

您可以在 shell 中创建和使用环境变量，而无需使用 Python：

//// tab | Linux、macOS、Windows Bash

<div class="termy">

```console
// 您可以创建一个名为 MY_NAME 的环境变量

				defer cpuid.CPU.Enable(cpuid.AVX2)
			}
			if simdjson.SupportedCPU() {
				t.Fatal("setup error: expected cpu to be unsupported")
			}
			testReq := testCase.requestXML
			if len(testReq) == 0 {
				var escaped bytes.Buffer
				xml.EscapeText(&escaped, []byte(testCase.query))
				testReq = []byte(fmt.Sprintf(defRequest, escaped.String()))
			}
			s3Select, err := NewS3Select(bytes.NewReader(testReq))
			if err != nil {

 * from the Apache HTTP Client test suite.
 */
class HostnameVerifierTest {
  private val verifier = OkHostnameVerifier

  @RegisterExtension
  var platform = PlatformRule()

  @Test fun verify() {
    val session = FakeSSLSession()
    assertThat(verifier.verify("localhost", session)).isFalse()
  }

  @Test fun verifyCn() {
    // CN=foo.com

					Type:      ObjectType,
					Flags:     0,
				}},
			},
		},
	}
	inputSerialized := make([]metaCacheEntry, len(inputs))
	for i, xl := range inputs {
		xl.sortByModTime()
		var err error
		entry := metaCacheEntry{
			name: "testobject",
		}
		entry.metadata, err = xl.AppendTo(nil)
		if err != nil {
			t.Fatal(err)
		}
		inputSerialized[i] = entry
	}

						{PrimaryKey: "ID", PrimarySchema: "Country", ForeignKey: "CountryID", ForeignSchema: "Org"},
					},
				},
			},
		},
	})
}

func TestVariableRelation(t *testing.T) {
	var result struct {
		User
	}

	checkStructRelation(t, &result, Relation{
		Name: "Account", Type: schema.HasOne, Schema: "", FieldSchema: "Account",
		References: []Reference{

```

**Not**:

Eğer bu konu hakkında bilginiz yoksa <a href="https://fastapi.tiangolo.com/tr/async/#in-a-hurry" target="_blank">`async` ve `await`</a> dokümantasyonundaki _"Aceleniz mi var?"_ kısmını kontrol edebilirsiniz.

</details>

### Kodu Çalıştıralım

Sunucuyu aşağıdaki komutla çalıştıralım:

<div class="termy">

```console
$ uvicorn main:app --reload

 *  Fix: Websockets no longer rebuffer socket streams.
 *  Fix: Websockets are now better at handling close frames.
 *  Fix: Content type matching is now case insensitive.
 *  Fix: `Vary` headers are not lost with `android.net.http.HttpResponseCache`.
 *  Fix: HTTP/2 wasn't enforcing stream timeouts when writing the underlying
    connection. Now it is.

    for (int i = 0; i < map.segments.length; i++) {
      assertEquals(segmentSize, map.segments[i].table.length());
    }
  }

  public void testSetMaximumSize() {
    // vary maximumSize wrt concurrencyLevel

    for (int maxSize = 1; maxSize < 100; maxSize++) {
      checkMaximumSize(1, 8, maxSize);
      checkMaximumSize(2, 8, maxSize);
      checkMaximumSize(4, 8, maxSize);

    for (int i = 0; i < map.segments.length; i++) {
      assertEquals(segmentSize, map.segments[i].table.length());
    }
  }

  public void testSetMaximumSize() {
    // vary maximumSize wrt concurrencyLevel

    for (int maxSize = 1; maxSize < 100; maxSize++) {
      checkMaximumSize(1, 8, maxSize);
      checkMaximumSize(2, 8, maxSize);
      checkMaximumSize(4, 8, maxSize);

- There is now support for collecting pod logs under `/var/log/pods/NAMESPACE_NAME_UID` to stackdriver with `k8s_pod` resource type. ([#74502](https://github.com/kubernetes/kubernetes/pull/74502), [@Random-Liu](https://github.com/Random-Liu))