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 the Matrix specification for more details of the algorithm used for federation connections, and delegate.md for instructions on setting up delegation.

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. The following sections detail the configuration of the reverse proxy and the homeserver.

Reverse-proxy configuration examples

NOTE: You only need one of these.

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;
            # Nginx by default only allows file uploads up to 1M in size
            # Increase client_max_body_size to match max_upload_size defined in homeserver.yaml
            client_max_body_size 10M;
        }
    }

    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;
        }
    }

NOTE: 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

    <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>

NOTE: ensure the nocanon options are included.

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

Homeserver Configuration

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.

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