Peer to peer networking in Unity using WebRTC and a free Heroku server for signaling.

The general idea is that you use the free WebRTC plugin for unity then use a free Heroku server as your signaling server. There are a lot of small details like the server shutting down automatically (even if you don't want it to) after a few minutes of inactivity that just took some fiddling to figure out but I have made small tweaks that fix those issues. In general the way it works is one person "hosts" a "server" at an id they chose (this can be pretty much any string). The quotes are because unlike a traditional server all this does is two things:

1. The WebRTC protocol is such that anyone else that connects with that id is initially connected to that server

2. Once they are connected it sends them a list of all the current peers, and each current peer gets notified by the server that that peer joined.

After that, a peer can send messages to another peer without going through the server, which is the definition of a peer to peer network :)

Here's how to do it:

1. Make an account on https://www.heroku.com/. It is free and doesn't even require you to enter payment info
2. Go into https://dashboard.heroku.com and click New, then Create New App.
3. Pick some random app name or let it choose one for you it doesn't really matter because this is just the websocket url that no one will see. Mine is nameless-scrubland-88927 but insert yours into the commands below instead
4. Install the heroku cli, nodejs, and npm
5. Clone this repo

git clone https://github.com/Phylliida/UnityP2P.git

then copy the server code (HerokuServer) into a directory without the .git file

6. In that directory, to login call

heroku login

7. Then create a new git repo there that will store your server code (Heroku works by having a git repo you manage your server code with)

git init

heroku git:remote -a nameless-scrubland-88927

(except use your server instead)

8. Now deploy your server

npm install

git add .

git commit -am "Initial upload"

git push -f heroku master

The -f (force) you shouldn't usually do but we need to override the initial configuration and this is the easiest way to do that.

You can tweak the config.json file if you want but that isn't really needed. You should also generate your own certificates in production but these work fine for testing small projects.

9. Open Unity, then select the UnityProject folder in this git repo to open it
10. Open the scene ExampleP2P (in the Assets folder) if it is not already open
11. In the ExampleP2PServer and ExampleP2PClient scripts attached to the server and client objects (respectively), change the Signaling Server variable to

wss://nameless-scrubland-88927.herokuapp.com

except use your sever instead. Note that you don't add the ports on the end.

12. Press play. This runs a server and a client, so look at the debug logs and you should see things happening :)

I haven't documented things yet but if you look at the ExampleP2PServer and ExampleP2PClient code it is simple enough that it should give you a jist of what is going on