reverse_proxy.rst

Using a reverse proxy with Synapse

It is recommended to put a reverse proxy such as nginx, Apache, Caddy or HAProxy 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 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;
      }
  }

  Do not add a / after the port in proxy_pass, otherwise nginx will canonicalise/normalise the URI.

• 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;
  
      AllowEncodedSlashes NoDecode
      ProxyPass /_matrix http://127.0.0.1:8008/_matrix nocanon
      ProxyPassReverse /_matrix http://127.0.0.1:8008/_matrix
  </VirtualHost>
  
  <VirtualHost *:8448>
      SSLEngine on
      ServerName example.com;
  
      AllowEncodedSlashes NoDecode
      ProxyPass /_matrix http://127.0.0.1:8008/_matrix nocanon
      ProxyPassReverse /_matrix http://127.0.0.1:8008/_matrix
  </VirtualHost>

• HAProxy:

  frontend https
    bind :::443 v4v6 ssl crt /etc/ssl/haproxy/ strict-sni alpn h2,http/1.1
  
    # Matrix client traffic
    acl matrix-host hdr(host) -i matrix.example.com
    acl matrix-path path_beg /_matrix
  
    use_backend matrix if matrix-host matrix-path
  
  frontend matrix-federation
    bind :::8448 v4v6 ssl crt /etc/ssl/haproxy/synapse.pem alpn h2,http/1.1
    default_backend matrix
  
  backend matrix
    server matrix 127.0.0.1:8008

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.