Clarifications for reverse proxy docs (#4607)

Factor out the reverse proxy info to a separate file, add some more info on
reverse-proxying the federation port.

1 files changed, 94 insertions, 0 deletions

diff --git a/docs/reverse_proxy.rst b/docs/reverse_proxy.rst
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+Using a reverse proxy with Synapse
+==================================
+
+It is recommended to put a reverse proxy such as
+`nginx <https://nginx.org/en/docs/http/ngx_http_proxy_module.html>`_,
+`Apache <https://httpd.apache.org/docs/current/mod/mod_proxy_http.html>`_,
+`Caddy <https://caddyserver.com/docs/proxy>`_ or
+`HAProxy <https://www.haproxy.org/>`_ in front of Synapse. One advantage of
+doing so is that it means that you can expose the default https port (443) to
+Matrix clients without needing to run Synapse with root privileges.
+
+**NOTE**: Your reverse proxy must not 'canonicalise' or 'normalise' the
+requested URI in any way (for example, by decoding ``%xx`` escapes). Beware
+that Apache *will* canonicalise URIs unless you specifify ``nocanon``.
+
+When setting up a reverse proxy, remember that Matrix clients and other Matrix
+servers do not necessarily need to connect to your server via the same server
+name or port. Indeed, clients will use port 443 by default, whereas servers
+default to port 8448. Where these are different, we refer to the 'client port'
+and the 'federation port'. See `Setting up federation
+<../README.rst#setting-up-federation>`_ for more details of the algorithm used for
+federation connections.
+
+Let's assume that we expect clients to connect to our server at
+``https://matrix.example.com``, and other servers to connect at
+``https://example.com:8448``. Here are some example configurations:
+
+* nginx::
+
+      server {
+          listen 443 ssl;
+          listen [::]:443 ssl;
+          server_name matrix.example.com;
+
+          location /_matrix {
+              proxy_pass http://localhost:8008;
+              proxy_set_header X-Forwarded-For $remote_addr;
+          }
+      }
+
+      server {
+          listen 8448 ssl default_server;
+          listen [::]:8448 ssl default_server;
+          server_name example.com;
+
+          location / {
+              proxy_pass http://localhost:8008;
+              proxy_set_header X-Forwarded-For $remote_addr;
+          }
+      }
+
+* Caddy::
+
+      matrix.example.com {
+        proxy /_matrix http://localhost:8008 {
+          transparent
+        }
+      }
+
+      example.com:8448 {
+        proxy / http://localhost:8008 {
+          transparent
+        }
+      }
+
+* Apache (note the ``nocanon`` options here!)::
+
+      <VirtualHost *:443>
+          SSLEngine on
+          ServerName matrix.example.com;
+
+          <Location /_matrix>
+              ProxyPass http://127.0.0.1:8008/_matrix nocanon
+              ProxyPassReverse http://127.0.0.1:8008/_matrix
+          </Location>
+      </VirtualHost>
+
+      <VirtualHost *:8448>
+          SSLEngine on
+          ServerName example.com;
+
+          <Location />
+              ProxyPass http://127.0.0.1:8008/_matrix nocanon
+              ProxyPassReverse http://127.0.0.1:8008/_matrix
+          </Location>
+      </VirtualHost>
+
+You will also want to set ``bind_addresses: ['127.0.0.1']`` and ``x_forwarded: true``
+for port 8008 in ``homeserver.yaml`` to ensure that client IP addresses are
+recorded correctly.
+
+Having done so, you can then use ``https://matrix.example.com`` (instead of
+``https://matrix.example.com:8448``) as the "Custom server" when connecting to
+Synapse from a client.