# 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());

    * Esta es una de las razones por las que es muy útil cuando el mismo TLS Termination Proxy también se encarga del proceso de renovación del certificado.

    * 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.

    override val timestampNs: Long,
    override val call: Call,
    val inetSocketAddress: InetSocketAddress,
    val proxy: Proxy?,
  ) : CallEvent()

  data class ConnectEnd(
    override val timestampNs: Long,
    override val call: Call,
    val inetSocketAddress: InetSocketAddress,
    val proxy: Proxy?,
    val protocol: Protocol?,
  ) : CallEvent() {
    override fun closes(event: CallEvent): Boolean =

    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,
  ) {

      }

    /**
     * Sets the HTTP proxy that will be used by connections created by this client. This takes
     * precedence over [proxySelector], which is only honored when this proxy is null (which it is
     * by default). To disable proxy use completely, call `proxy(Proxy.NO_PROXY)`.
     */
    fun proxy(proxy: Proxy?) =
      apply {
        if (proxy != this.proxy) {
          this.routeDatabase = null
        }