Update README.md

README.md

@@ -1,6 +1,113 @@
 # Rel
 
-TURN server.
+TURN server in Elixir
+
+Aims to implement:
+- [RFC 5766](https://datatracker.ietf.org/doc/html/rfc5766) and [RFC 6156](https://datatracker.ietf.org/doc/html/rfc6156#autoid-7).
+- [RFC 6156](https://datatracker.ietf.org/doc/html/rfc6156#autoid-7)
+
+This project is in early stage of development and some of the fetures included in RFCs might be missing.
+Expect breaking changes.
+
+Supports authentication described in [A REST API For Access To TURN Services](https://datatracker.ietf.org/doc/html/draft-uberti-rtcweb-turn-rest-00#section-2.2).
+
+## Public deployment
+
+If you're in need of TURN server for testing purposes, feel free to use this Rel public deployment at `turn.bigcow.ovh`. In case of any
+irregularity or bugs, please open an issue with description of the problem. DO NOT use this deployment in production, as it's intended to be an aid in developement only.
+
+To obtain the credentials, use the build-in credentials mechanism. It does not require any authentication, but the credentials must be refreshed after 3 hours if not used.
+
+```console
+$ curl -X POST "https://turn.bigcow.ovh/?service=turn&username=johnsmith"
+{"password":"l6hs9SzUgudFeb5XjrfCfOWKeOQ=","ttl":1728,"uris":["turn:167.235.241.140:3478?transport=udp"],"username":"1691574817:johnsmith"}⏎
+```
+
+Use the obtained credentials in e.g. WebRTC's `RTCPeerConnection`:
+
+```js
+pc = new RTCPeerConnection({
+  iceServers: [
+    {
+      credential: "l6hs9SzUgudFeb5XjrfCfOWKeOQ=",
+      urls: "turn:167.235.241.140:3478?transport=udp", 
+      username: "1691574817:johnsmith" 
+    }
+  ]
+});
+```
+
+## Installation
+
+1. From source
+
+```console
+git clone https://github.com/elixir-webrtc/rel.git
+cd rel
+mix deps.get
+mix run --no-halt
+```
+
+2. In Docker
+
+```console
+docker run ghcr.io/webrtc-elixir/rel:latest
+```
+
+## Features and configuration
+
+Currently, Rel is configured via environment variables.
+
+# TURN server
+
+Rel by default listens on 0.0.0.0:3478/UDP for TURN traffic. This can be configured via `LISTEN_IP` and `LISTEN_PORT`.
+
+```console
+LISTEN_IP=0.0.0.0
+LISTEN_PORT=3478
+```
+
+`EXTERNAL_LISTEN_IP` is the IP address under which Rel is visible to clients. By default, Rel will try to guess the address
+based on active network interfaces, but this must be set explicitly when e.g. using Docker without `--network host`.
+
+```console
+EXTERNAL_LISTEN_IP=167.235.241.140
+```
+
+By default, Rel will use the same addresses (`RELAY_IP == LISTEN_IP and EXTERNAL_RELAY_IP == EXTERNAL_LISTEN_IP`) to open allocations, but this
+can be set to something else:
+
+```console
+RELAY_IP=0.0.0.0
+EXTERNAL_RELAY_IP=167.235.241.140
+```
+
+Remember to set the `DOMAIN_NAME` variable specific to your deployment. It's used in e.g. `SOFTWARE` STUN attributes.
+
+```console
+DOMAIN_NAME=my-amazing-turn.com
+```
+
+
+### Auth
+
+Auth Provider is an HTTP endpoint providing credentials required by *A REST API For Access To TURN Services*.
+It's default it is available at http://127.0.0.1:4000/, but the address and encryption can be configured:
+
+```console
+AUTH_PROVIDER_IP=127.0.0.1
+AUTH_PROVIDER_PORT=4000
+AUTH_PROVIDER_USE_TLS=true
+KEY_FILE_PAHT=./rel.key
+CERT_FILE_PATH./rel.cert
+```
+
+### Metrics
+
+By default Rel provides Prometheusmetrics at http://127.0.0.1:9578/metrics. The address can be configured:
+
+```console
+METRICS_IP=127.0.0.1
+METRICS_PORT=9568
+```
 
-Implementation of [RFC 5766](https://datatracker.ietf.org/doc/html/rfc5766) and [RFC 6156](https://datatracker.ietf.org/doc/html/rfc6156#autoid-7).
-Supports authentication described in [A REST API For Access to TURN Services](https://datatracker.ietf.org/doc/html/draft-uberti-rtcweb-turn-rest-00).