# Configuring service discovery via .well-known


## Introduction

Service discovery lets various client programs which support it, to receive a full user id (e.g. `@username:example.com`) and determine where the Matrix server is automatically (e.g. `https://matrix.example.com`).

This lets your users easily connect to your Matrix server without having to customize connection URLs.

As [per the specification](https://matrix.org/docs/spec/client_server/r0.4.0.html#server-discovery) Matrix does service discovery using a `/.well-known/matrix/client` file hosted on the base domain (e.g. `example.com`).

However, this playbook installs your Matrix server on another domain (e.g. `matrix.example.com`) and not on the base domain (e.g. `example.com`), so it takes a little extra manual effort to set up the file.


## Prerequisites

To implement service discovery, your base domain's server (e.g. `example.com`) needs to support HTTPS.


## Setting it up

To make things easy for you to set up, this playbook generates and hosts the well-known file on the Matrix domain's server (e.g. `https://matrix.example.com/.well-known/matrix/client`), even though this is the wrong place to host it.

You have 2 options when it comes to installing the file on the base domain's server:

1) (Option 1): **Copying the file manually** to your base domain's server

All it takes is copying the `/.well-known/matrix/client` from the Matrix server (e.g. `matrix.example.com`) to your base domain's server (`example.com`).

This is easy to do and possibly your only choice if you can only host static files from the base domain's server.
It is, however, a little fragile, as future updates performed by this playbook may regenerate the well-known file and you may need to notice that and copy it again.

2) (Option 2): **Setting up reverse-proxying** of the well-known file from the base domain's server to the Matrix server.

This option is less fragile and generally better.

On the base domain's server (e.g. `example.com`), you can set up reverse-proxying, so that any access for the `/.well-known/matrix` location prefix is forwarded to the Matrix domain's server (e.g. `matrix.example.com`).

**For nginx**, it would be something like this:

```nginx
# This is your HTTPS-enabled server for DOMAIN.
server {
	server_name DOMAIN;

	location /.well-known/matrix {
		proxy_pass https://matrix.DOMAIN/.well-known/matrix;
		proxy_set_header X-Forwarded-For $remote_addr;
	}

	# other configuration
}
```

**For Apache**, it would be something like this:

```apache
<VirtualHost *:443>
	ServerName DOMAIN

	SSLProxyEngine on
	<Location /.well-known/matrix>
		ProxyPass "https://matrix.DOMAIN/.well-known/matrix"
	</Location>

	# other configuration
</VirtualHost>
```

Make sure to:

- **replace `DOMAIN`** in the server configuration with your actual domain name
- and: to **do this for the HTTPS-enabled server block**, as that's where Matrix expects the file to be


## Confirming it works

No matter which method you've used to set up the well-known file, if you've done it correctly you should be able to see a JSON file at a URL like this: `https://matrix.<domain>/.well-known/matrix/client`.