## Proxy Forwarded Headers { #proxy-forwarded-headers }

When using a proxy to handle HTTPS, your **application server** (for example Uvicorn via FastAPI CLI) doesn't known anything about the HTTPS process, it communicates with plain HTTP with the **TLS Termination Proxy**.

background-color:#aaaaaa; } td a img { border-width:0; margin-left:5pt; vertical-align:middle;} <!-- var number = /^\d*$/; function showTable(title, headers, content) { text = "<h3>" + title + "</h3><p>"; if (content.length > 0) { text += "<table border=\"1\" cellpadding=\"5\" cellspacing=\"0\">"; if (headers.length > 0) { text += "<tr>"; headerArray = headers.split(","); for (i = 0; i < headerArray.length; i++) { text += "<th>" + headerArray[i] + "</th>"; } text += "</tr>"; } rows = content.split(";");...

 * limitations under the License.
 */
package mockwebserver3

import okhttp3.Headers

/** An HTTP request initiated by the server. */
public class PushPromise(
  public val method: String,
  public val path: String,
  public val headers: Headers,
  public val response: MockResponse,

        .build();

    try (Response response = client.newCall(request).execute()) {
      if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);

      Headers responseHeaders = response.headers();
      for (int i = 0; i < responseHeaders.size(); i++) {
        System.out.println(responseHeaders.name(i) + ": " + responseHeaders.value(i));
      }

      System.out.println(response.body().string());

    mod = importlib.import_module(f"docs_src.header_param_models.{request.param}")

    client = TestClient(mod.app)
    client.headers.clear()
    return client


def test_header_param_model(client: TestClient):
    response = client.get(
        "/items/",
        headers=[
            ("save-data", "true"),
            ("if-modified-since", "yesterday"),
            ("traceparent", "123"),

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.squareup.okhttp3.maventest;

import java.io.IOException;

import okhttp3.Headers;
import okhttp3.HttpUrl;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

public class SampleHttpClient {
  private final OkHttpClient client;

  public SampleHttpClient() {

@app.middleware("http")
async def custom_middleware(
    request: Request, call_next: Callable[[Request], Awaitable[Response]]
):
    response = await call_next(request)
    response.headers["custom"] = "foo"
    return response


@app.get("/user", dependencies=[Depends(set_up_request_state_dependency)])
def get_user():
    request_state = legacy_request_state_context_var.get()
    assert request_state

**FastAPI** will use that *temporal* response to extract the cookies (also headers and status code), and will put them in the final response that contains the value you returned, filtered by any `response_model`.

You can also declare the `Response` parameter in dependencies, and set cookies (and headers) in them.

## Return a `Response` directly { #return-a-response-directly }

@app.get("/items/{item_id}")
async def read_item(item_id: str):
    if item_id not in items:
        raise HTTPException(
            status_code=404,
            detail="Item not found",
            headers={"X-Error": "Some custom header"},
        )
    return {"item": items[item_id]}


@app.get("/http-no-body-statuscode-exception")
async def no_body_status_code_exception():
    raise HTTPException(status_code=204)

  private val client = OkHttpClient()

  fun run() {
    val request =
      Request
        .Builder()
        .url("https://api.github.com/repos/square/okhttp/issues")
        .header("User-Agent", "OkHttp Headers.java")
        .addHeader("Accept", "application/json; q=0.5")
        .addHeader("Accept", "application/vnd.github.v3+json")
        .build()

    client.newCall(request).execute().use { response ->