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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 specify 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.

Endpoints that are part of the standardised Matrix specification are located under /_matrix, whereas endpoints specific to Synapse are located under /_synapse/client.

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;

    # For the federation port
    listen 8448 ssl default_server;
    listen [::]:8448 ssl default_server;

    server_name matrix.example.com;

    location ~* ^(\/_matrix|\/_synapse\/client) {
        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 50M;
    }
}

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

Caddy 1

matrix.example.com {
  proxy /_matrix http://localhost:8008 {
    transparent
  }

  proxy /_synapse/client http://localhost:8008 {
    transparent
  }
}

example.com:8448 {
  proxy / http://localhost:8008 {
    transparent
  }
}

Caddy 2

matrix.example.com {
  reverse_proxy /_matrix/* http://localhost:8008
  reverse_proxy /_synapse/client/* http://localhost:8008
}

example.com:8448 {
  reverse_proxy http://localhost:8008
}

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
    ProxyPass /_synapse/client http://127.0.0.1:8008/_synapse/client nocanon
    ProxyPassReverse /_synapse/client http://127.0.0.1:8008/_synapse/client
</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.

NOTE 2: It appears that Synapse is currently incompatible with the ModSecurity module for Apache (mod_security2). If you need it enabled for other services on your web server, you can disable it for Synapse's two VirtualHosts by including the following lines before each of the two </VirtualHost> above:

<IfModule security2_module>
    SecRuleEngine off
</IfModule>

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
  acl matrix-path path_beg /_synapse/client

  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.

Health check endpoint

Synapse exposes a health check endpoint for use by reverse proxies. Each configured HTTP listener has a /health endpoint which always returns 200 OK (and doesn't get logged).

Synapse administration endpoints

Endpoints for administering your Synapse instance are placed under /_synapse/admin. These require authentication through an access token of an admin user. However as access to these endpoints grants the caller a lot of power, we do not recommend exposing them to the public internet without good reason.

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