287 lines
11 KiB
ReStructuredText
287 lines
11 KiB
ReStructuredText
nghttpx - HTTP/2 proxy - HOW-TO
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===============================
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nghttpx is a proxy translating protocols between HTTP/2 and other
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protocols (e.g., HTTP/1, SPDY). It operates in several modes and each
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mode may require additional programs to work with. This article
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describes each operation mode and explains the intended use-cases. It
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also covers some useful options later.
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Default mode
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------------
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If nghttpx is invoked without any ``-s``, ``-p`` and ``--client``, it
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operates in default mode. In this mode, nghttpx frontend listens for
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HTTP/2 requests and translates them to HTTP/1 requests. Thus it works
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as reverse proxy (gateway) for HTTP/2 clients to HTTP/1 web server.
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HTTP/1 requests are also supported in frontend as a fallback. If
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nghttpx is linked with spdylay library and frontend connection is
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SSL/TLS, the frontend also supports SPDY protocol.
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By default, this mode's frontend connection is encrypted using
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SSL/TLS. So server's private key and certificate must be supplied to
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the command line (or through configuration file). In this case, the
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fontend protocol selection will is done via ALPN or NPN.
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With ``--frontend-no-tls`` option, user can turn off SSL/TLS in
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frontend connection. In this case, SPDY protocol is not available
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even if spdylay library is liked to nghttpx. HTTP/2 and HTTP/1 are
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available on the frontend and a HTTP/1 connection can be upgraded to
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HTTP/2 using HTTP Upgrade. Starting HTTP/2 connection by sending
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HTTP/2 connection preface is also supported.
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The backend is supposed to be HTTP/1 Web server. For example, to make
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nghttpx listen to encrypted HTTP/2 requests at port 8443, and a
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backend HTTP/1 web server is configured to listen to HTTP/1 request at
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port 8080 in the same host, run nghttpx command-line like this::
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$ nghttpx -f0.0.0.0,8443 -b127.0.0.1,8080 /path/to/server.key /path/to/server.crt
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Then HTTP/2 enabled client can access to the nghttpx in HTTP/2. For
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example, you can send GET request to the server using nghttp::
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$ nghttp -nv https://localhost:8443/
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HTTP/2 proxy mode
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-----------------
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If nghttpx is invoked with ``-s`` option, it operates in HTTP/2 proxy
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mode. The supported protocols in frontend and backend connections are
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the same in `default mode`_. The difference is that this mode acts
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like forward proxy and assumes the backend is HTTP/1 proxy server
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(e.g., squid, traffic server). So HTTP/1 request must include
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absolute URI in request line.
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By default, frontend connection is encrypted, this mode is also called
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secure proxy. If nghttpx is linked with spdylay, it supports SPDY
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protocols and it works as so called SPDY proxy.
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With ``--frontend-no-tls`` option, SSL/TLS is turned off in frontend
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connection, so the connection gets insecure.
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The backend must be HTTP/1 proxy server. nghttpx only supports 1
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backend server address. It translates incoming requests to HTTP/1
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request to backend server. The backend server performs real proxy
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work for each request, for example, dispatching requests to the origin
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server and caching contents.
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For example, to make nghttpx listen to encrypted HTTP/2 requests at
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port 8443, and a backend HTTP/1 proxy server is configured to listen
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to HTTP/1 request at port 8080 in the same host, run nghttpx
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command-line like this::
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$ nghttpx -s -f'*,8443' -b127.0.0.1,8080 /path/to/server.key /path/to/server.crt
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At the time of this writing, Firefox nightly supports HTTP/2 proxy.
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Chromium can use nghttpx as secure (SPDY) proxy and will support
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HTTP/2 proxy in the near future.
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To make Firefox nightly or Chromium use nghttpx as HTTP/2 or SPDY
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proxy, user has to create proxy.pac script file like this:
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.. code-block:: javascript
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function FindProxyForURL(url, host) {
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return "HTTPS SERVERADDR:PORT";
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}
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``SERVERADDR`` and ``PORT`` is the hostname/address and port of the
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machine nghttpx is running. Please note that both Firefox nightly and
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Chromium requires valid certificate for secure proxy.
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For Firefox nightly, open Preference window and select Advanced then
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click Network tab. Clicking Connection Settings button will show the
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dialog. Select "Automatic proxy configuration URL" and enter the path
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to proxy.pac file, something like this::
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file:///path/to/proxy.pac
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For Chromium, use following command-line::
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$ google-chrome --proxy-pac-url=file:///path/to/proxy.pac --use-npn
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Squid may work as out-of-box. Traffic server requires to be
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configured as forward proxy. Here is the minimum configuration items
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to edit::
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CONFIG proxy.config.reverse_proxy.enabled INT 0
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CONFIG proxy.config.url_remap.remap_required INT 0
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Consult Traffic server `documentation
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<https://docs.trafficserver.apache.org/en/latest/admin/forward-proxy.en.html>`_
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to know how to configure traffic server as forward proxy and its
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security implications.
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Client mode
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-----------
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If nghttpx is invoked with ``--client`` option, it operates in client
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mode. In this mode, nghttpx listens for plain, unencrypted HTTP/2 and
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HTTP/1 requests and translates them to encrypted HTTP/2 requests to
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the backend. User cannot enable SSL/TLS in frontend connection.
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HTTP/1 frontend connection can be upgraded to HTTP/2 using HTTP
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Upgrade. To disable SSL/TLS in backend connection, use
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``--backend-no-tls`` option.
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The backend connection is created one per worker (thread).
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The backend server is supporsed to be a HTTP/2 web server (e.g.,
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nghttpd). The one use-case of this mode is utilize existing HTTP/1
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clients to test HTTP/2 deployment. Suppose that HTTP/2 web server
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listens to port 80 without encryption. Then run nghttpx as client
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mode to access to that web server::
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$ nghttpx --client -f127.0.0.1,8080 -b127.0.0.1,80 --backend-no-tls
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.. note::
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You may need ``-k`` option if HTTP/2 server enables SSL/TLS and
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its certificate is self-signed. But please note that it is
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insecure.
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Then you can use curl to access HTTP/2 server via nghttpx::
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$ curl http://localhost:8080/
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Client proxy mode
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-----------------
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If nghttpx is invoked with ``-p`` option, it operates in client proxy
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mode. This mode behaves like `client mode`_, but it works like
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forward proxy. So HTTP/1 request must include absolute URI in request
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line.
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HTTP/1 frontend connection can be upgraded to HTTP/2 using HTTP
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Upgrade. To disable SSL/TLS in backend connection, use
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``--backend-no-tls`` option.
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The backend connection is created one per worker (thread).
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The backend server must be a HTTP/2 proxy. You can use nghttpx in
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`HTTP/2 proxy mode`_ as backend server. The one use-case of this mode
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is utilize existing HTTP/1 clients to test HTTP/2 connections between
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2 proxies. The another use-case is use this mode to aggregate local
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HTTP/1 connections to one HTTP/2 backend encrypted connection. This
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makes HTTP/1 clients which does not support secure proxy can use
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secure HTTP/2 proxy via nghttpx client mode.
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Suppose that HTTP/2 proxy listens to port 8443, just like we saw in
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`HTTP/2 proxy mode`_. To run nghttpx in client proxy mode to access
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that server, invoke nghttpx like this::
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$ nghttpx -p -f127.0.0.1,8080 -b127.0.0.1,8443
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.. note::
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You may need ``-k`` option if HTTP/2 server's certificate is
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self-signed. But please note that it is insecure.
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Then you can use curl to issue HTTP request via HTTP/2 proxy::
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$ curl --http-proxy=http://localhost:8080 http://www.google.com/
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You can configure web browser to use localhost:8080 as forward
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proxy.
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HTTP/2 bridge mode
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------------------
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If nghttpx is invoked with ``--http2-bridge`` option, it operates in
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HTTP/2 bridge mode. The supported protocols in frontend connections
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are the same in `default mode`_. The protocol in backend is HTTP/2
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only.
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With ``--frontend-no-tls`` option, SSL/TLS is turned off in frontend
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connection, so the connection gets insecure. To disable SSL/TLS in
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backend connection, use ``--backend-no-tls`` option.
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The backend server is supporsed to be a HTTP/2 web server or HTTP/2
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proxy. If backend server is HTTP/2 proxy, use
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``--no-location-rewrite`` option to disable rewriting location header
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field.
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The use-case of this mode is aggregate the incoming connections to one
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HTTP/2 connection. One backend HTTP/2 connection is created per
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worker (thread).
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Disable SSL/TLS
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---------------
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In `default mode`_, `HTTP/2 proxy mode`_ and `HTTP/2 bridge mode`_,
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frontend connections are encrypted with SSL/TLS by default. To turn
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off SSL/TLS, use ``--frontend-no-tls`` option. If this option is
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used, the private key and certificate are not required to run nghttpx.
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In `client mode`_, `client proxy mode`_ and `HTTP/2 bridge mode`_,
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backend connections are encrypted with SSL/TLS by default. To turn
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off SSL/TLS, use ``--backend-no-tls`` option.
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Specifying additional CA certificate
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------------------------------------
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By default, nghttpx tries to read CA certificate from system. But
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depending on the system you use, this may fail or is not supported.
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To specify CA certificate manually, use ``--cacert`` option. The
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specified file must be PEM format and can contain multiple
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certificates.
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By default, nghttpx validates server's certificate. If you want to
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turn off this validation, knowing this is really insecure and what you
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are doing, you can use ``-k`` option to disable certificate
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validation.
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Read/write rate limit
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---------------------
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nghttpx supports transfer rate limiting on frontend connections. You
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can do rate limit per worker (thread) for reading and writeing
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individually.
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To rate limit per worker (thread), use ``--worker-read-rate`` and
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``--worker-read-burst`` options. For writing, use
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``--worker-write-rate`` and ``--worker-write-burst``.
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Please note that rate limit is performed on top of TCP and nothing to
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do with HTTP/2 flow control.
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Rewriting location header field
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-------------------------------
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nghttpx automatically rewrites location response header field if the
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following all conditions satisfy:
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* URI in location header field is not absolute URI or is not https URI.
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* URI in location header field includes non empty host component.
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* host (without port) in URI in location header field must match the
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host appearing in :authority or host header field.
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When rewrite happens, URI scheme and port are replaced with the ones
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used in frontend, and host is replaced with which appears in
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:authority or host request header field. :authority header field has
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precedence. If the above conditions are not met with the host value
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in :authority header field, rewrite is retried with the value in host
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header field.
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Hot deploy
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----------
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nghttpx supports hot deploy feature using signals. The hot deploy in
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nghttpx is multi step process. First send USR2 signal to nghttpx
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process. It will do fork and execute new executable, using same
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command-line arguments and environment variables. At this point, both
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current and new processes can accept requests. To gracefully shutdown
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current process, send QUIT signal to current nghttpx process. When
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all existing frontend connections are done, the current process will
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exit. At this point, only new nghttpx process exists and serves
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incoming requests.
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Re-opening log files
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--------------------
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When rotating log files, it is desirable to re-open log files after
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log rotation daemon renamed existing log files. To tell nghttpx to
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re-open log files, send USR1 signal to nghttpx process. It will
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re-open files specified by ``--accesslog-file`` and
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``--errorlog-file`` options.
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