# Server Delegation To have a server on a subdomain (e.g. `matrix.`) handle Matrix federation traffic for the base domain (``), we need to instruct the Matrix network of such a delegation. By default, this playbook guides you into setting up [Server Delegation via a well-known file](#server-delegation-via-a-well-known-file). However, that method may have some downsides that are not to your liking. Hence this guide about alternative ways to set up Server Delegation. It is a complicated matter, so unless you are affected by the [Downsides of well-known-based Server Delegation](#downsides-of-well-known-based-server-delegation), we suggest you stay on the simple/default path. ## Server Delegation via a well-known file Serving a `/.well-known/matrix/server` file from the base domain is the most straightforward way to set up server delegation, but it suffers from some problems that we list in [Downsides of well-known-based Server Delegation](#downsides-of-well-known-based-server-delegation). As we already mention in [Configuring DNS](configuring-dns.md) and [Configuring Service Discovery via .well-known](configuring-well-known.md), this playbook already properly guides you into setting up such delegation by means of a `/.well-known/matrix/server` file served from the base domain (``). If this is okay with you, feel free to not read ahead. ### Downsides of well-known-based Server Delegation Server Delegation by means of a `/.well-known/matrix/server` file is the most straightforward, but suffers from the following downsides: - you need to have a working HTTPS server for the base domain (``) - any downtime on the base domain (``) or network trouble between the matrix subdomain (`matrix.`) and the base `` may cause Matrix Federation outages. As the [Server-Server spec says](https://matrix.org/docs/spec/server_server/r0.1.0.html#server-discovery): > Errors are recommended to be cached for up to an hour, and servers are encouraged to exponentially back off for repeated failures. If this is not a concern for you, feel free to not read ahead. Otherwise, you can decide to go against the default for this playbook, and instead set up [Server Delegation via a DNS SRV record (advanced)](#server-delegation-via-a-dns-srv-record-advanced). ## Server Delegation via a DNS SRV record (advanced) **NOTE**: doing Server Delegation via a DNS SRV record is a more advanced way to do it and is not the default for this playbook. As per the [Server-Server spec](https://matrix.org/docs/spec/server_server/r0.1.0.html#server-discovery), it's possible to do Server Delegation using only a SRV record (without a `/.well-known/matrix/server` file). This prevents you from suffering the [Downsides of well-known-based Server Delegation](#downsides-of-well-known-based-server-delegation). To use DNS SRV record validation, you need to: - ensure that `/.well-known/matrix/server` is **not served** from the base domain, as that would interfere with DNS SRV record Server Delegation. To make the playbook **not** generate and serve the file, use the following configuration: `matrix_well_known_matrix_server_enabled: false`. - ensure that you have a `_matrix._tcp` DNS SRV record for your base domain (``) with a value of `10 0 8448 matrix.` - ensure that you are serving the Matrix Federation API (tcp/8448) with a certificate for `` (not `matrix.`!). See below. ### Obtaining certificates How you can obtain a valid certificate for `` on the `matrix.` server is up to you. If `` and `matrix.` are hosted on the same machine, you can let the playbook obtain the certificate for you, by following our [Obtaining SSL certificates for additional domains](configuring-playbook-ssl-certificates.md#obtaining-ssl-certificates-for-additional-domains) guide. If `` and `matrix.` are not hosted on the same machine, you can copy over the certificate files manually. Don't forget that they may get renewed once in a while, so you may also have to transfer them periodically. How often you do that is up to you, as long as the certificate files don't expire. ### Serving the Federation API with your certificates Regardless of which method for obtaining certificates you've used, once you've managed to get certificates for your base domain onto the `matrix.` machine you can put them to use. Based on your setup, you have different ways to go about it: - [Serving the Federation API with your certificates and matrix-nginx-proxy](#serving-the-federation-api-with-your-certificates-and-matrix-nginx-proxy) - [Serving the Federation API with your certificates and another webserver](#serving-the-federation-api-with-your-certificates-and-another-webserver) - [Serving the Federation API with your certificates and Synapse handling Federation](#serving-the-federation-api-with-your-certificates-and-synapse-handling-federation) ### Serving the Federation API with your certificates and matrix-nginx-proxy **If you are using matrix-nginx-proxy**, a reverse-proxy webserver used by default in this playbook, you only need to override the certificates used for the Matrix Federation API. You can do that using: ```yaml # Adjust paths below to point to your certificate. # # NOTE: these are in-container paths. `/matrix/ssl` on the host is mounted into the container # at the same path (`/matrix/ssl`) by default, so if that's the path you need, it would be seamless. matrix_nginx_proxy_proxy_matrix_federation_api_ssl_certificate: /matrix/ssl/config/live/matrix./fullchain.pem matrix_nginx_proxy_proxy_matrix_federation_api_ssl_certificate_key: /matrix/ssl/config/live/matrix./privkey.pem ``` If your files are not in `/matrix/ssl` but in some other location, you would need to mount them into the container: ```yaml matrix_nginx_proxy_container_extra_arguments: - "--mount type=bind,src=/some/path/on/the/host,dst=/some/path/inside/the/container,ro" ``` You then refer to them (for `matrix_nginx_proxy_proxy_matrix_federation_api_ssl_certificate` and `matrix_nginx_proxy_proxy_matrix_federation_api_ssl_certificate_key`) by using `/some/path/inside/the/container`. Make sure to reload matrix-nginx-proxy once in a while (`systemctl reload matrix-nginx-proxy`), so that newer certificates can kick in. Reloading doesn't cause any downtime. ### Serving the Federation API with your certificates and another webserver **If you are NOT using matrix-nginx-proxy**, but rather some other webserver, you can set up reverse-proxying for the `tcp/8448` port by yourself. Make sure to use the proper certificates for `` (not for `matrix.`) when serving the `tcp/8448` port. Proxying needs to happen to `127.0.0.1:8048` (unencrypted Synapse federation listener). Make sure to reload/restart your webserver once in a while, so that newer certificates can kick in. ### Serving the Federation API with your certificates and Synapse handling Federation **Alternatively**, if you are **NOT using matrix-nginx-proxy** and **would rather not use your own webserver for Federation traffic**, you can let Synapse handle Federation by itself. To do that, make sure the certificate files are mounted into the Synapse container: ```yaml matrix_synapse_container_extra_arguments: - "--mount type=bind,src=/some/path/on/the/host,dst=/some/path/inside/the/container,ro" ``` You can then tell Synapse to serve Federation traffic over TLS on `tcp/8448`: ```yaml matrix_synapse_tls_federation_listener_enabled: true matrix_synapse_tls_certificate_path: /some/path/inside/the/container/certificate.crt matrix_synapse_tls_private_key_path: /some/path/inside/the/container/private.key ``` Make sure to reload Synapse once in a while (`systemctl reload matrix-synapse`), so that newer certificates can kick in. Reloading doesn't cause any downtime.