# Behind a Proxy { #behind-a-proxy }

In many situations, you would use a **proxy** like Traefik or Nginx in front of your FastAPI app.

These proxies could handle HTTPS certificates and other things.

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

    private const val PROXY_A_HOST = "proxya"
    private val proxyA =
      Proxy(
        Proxy.Type.HTTP,
        InetSocketAddress.createUnresolved(PROXY_A_HOST, PROXY_A_PORT),
      )

    private const val PROXY_B_PORT = 1002
    private const val PROXY_B_HOST = "proxyb"
    private val proxyB =
      Proxy(
        Proxy.Type.HTTP,

                    }

                    Proxy p = new Proxy();
                    p.setHost(proxy.getHost());
                    p.setProtocol(proxy.getProtocol());
                    p.setPort(proxy.getPort());
                    p.setNonProxyHosts(proxy.getNonProxyHosts());
                    p.setUserName(proxy.getUsername());
                    p.setPassword(proxy.getPassword());

      certificatePinner = null,
      proxyAuthenticator = proxyAuthenticator,
      proxy = proxy,
      protocols = protocols,
      connectionSpecs = connectionSpecs,
      proxySelector = proxySelector,
    )

  fun newRoute(
    address: Address = newAddress(),
    proxy: Proxy = this.proxy,
    socketAddress: InetSocketAddress = InetSocketAddress.createUnresolved(uriHost, uriPort),
  ): Route =

                            proxy = result.getProxy();

                            ProxyInfo proxyInfo = new ProxyInfo();
                            proxyInfo.setHost(proxy.getHost());
                            proxyInfo.setType(proxy.getProtocol());
                            proxyInfo.setPort(proxy.getPort());
                            proxyInfo.setNonProxyHosts(proxy.getNonProxyHosts());

    * Otherwise, you might have to stop the TLS Termination Proxy momentarily, start the renewal program to acquire the certificates, then configure them with the TLS Termination Proxy, and then restart the TLS Termination Proxy. This is not ideal, as your app(s) will not be available during the time that the TLS Termination Proxy is off.

    call: Call,
    inetSocketAddress: InetSocketAddress,
    proxy: Proxy,
    protocol: Protocol?,
  ) {
    logWithTime("connectEnd: $protocol")

    delegate.connectEnd(call, inetSocketAddress, proxy, protocol)
  }

  override fun connectFailed(
    call: Call,
    inetSocketAddress: InetSocketAddress,
    proxy: Proxy,
    protocol: Protocol?,
    ioe: IOException,
  ) {

      // If we used the ProxySelector, and got a IOException during connect, report the failure.
      if (route.address.proxy == null && route.proxy.type() != Proxy.Type.DIRECT) {
        route.address.proxySelector.connectFailed(
          route.address.url.toUri(),
          route.proxy.address(),
          e,
        )
      }
      user.connectFailed(route, null, e)

  }

  /**
   * Invoked after proxy selection.
   *
   * Note that the list of proxies is never null, but it may be a list containing
   * only [Proxy.NO_PROXY]. This comes up in several situations:
   *
   * * If neither a proxy nor proxy selector is configured.
   * * If the proxy is configured explicitly as [Proxy.NO_PROXY].
   * * If the proxy selector returns only [Proxy.NO_PROXY].
   * * If the proxy selector returns an empty list or null.

     */
    public String body() {
        return body;
    }

    /**
     * Sets the proxy for the request.
     *
     * @param proxy the proxy
     * @return this CurlRequest instance
     */
    public CurlRequest proxy(final Proxy proxy) {
        this.proxy = proxy;
        return this;
    }

    /**
     * Sets the character encoding for the request.
     *