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https://github.com/rj/bevygap

Utils to set up edgegap bevy game servers
https://github.com/rj/bevygap

bevy edgegap lightyear matchmaking multiplayer

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Utils to set up edgegap bevy game servers

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README 

        
# Bevygap – Multiplayer server management tools



This is a (WIP) toolkit for running multiplayer game servers on [Edgegap](https://edgegap.com), where the games are

built with Bevy using the [Lightyear](https://crates.io/crates/lightyear) networking library.



The goal is to have an easy-to-deploy system either yourself with docker-compose, or in the cloud,

to use Edgegap to spin up gameservers on demand. 



My testbed for this is [bevygap-spaceships](https://github.com/RJ/bevygap-spaceships) – a modified

stand-alone version of the `spaceships` example from the Lightyear repo.



# Live Demo



Is the [live demo of bevygap-spaceships](https://game.metabrew.com/bevygap-spaceships/) working? Hopefully!



# Documentation / Quickstart



Documentation by book: [The Bevygap Book](https://rj.github.io/bevygap/)



`mdbook serve -o book/` if you want to view it locally.



## Connection flow



* Game client talks to `bevygap_matchmaker_httpd` via websocket, asking to play, and ultimately expecting a response including a `ConnectToken` and gameserver `ip:port`.

* This makes a nats request to the matchmaker service

* An edgegap session is created, which corresponds to a gameserver instance (which may be autodeployed in response to this session creation)

* Matchmaker generates a Lightyear `ConnectToken`, and associates the token's `ClientId` with the edgegap session ID in NATS KV.

* Client uses the `ConnectToken` to connect to the gameserver

* Gameserver maintains a list of active connections in NATS KV, which the matchmaker watches.

* When a client disconnects, the gameserver removes their entry from `active_connection`, causing the matchmaker to delete the Edgegap session.



## Components



### bevygap_matchmaker



Clients wishing to connect to the game make a request to our matchmaker service, which then:



* Creates an Edgegap session (which may trigger a new server deployment)

* Creates a new Lightyear client id and connect token, associated with the session

* Stores the token/session mapping in NATS KV

* Returns the connect token, and gameserver IP and port to the client.

  (the gameserver ip+port will be a machine controlled by Edgegap, running your game server's docker image)

* Deletes edgegap sessions when clients disconnect, by watching `active_connections` in NATS KV



### bevygap_matchmaker_httpd



An http endpoint to make "i want to play" requests to the matchmaker.

The matchmaker itself only exposes a service to NATS, not http.



### bevygap_client_plugin



A bevy plugin for the game client, to replace the normal lightyear `commands.connect_client()` call.

The new `commands.bevygap_connect_client()` function will make a request to the matchmaker, then modify lightyear's config to set the supplied

game server socket address and connect token, then call `commands.connect_client()` for you.



### bevygap_server_plugin



A bevy plugin for the gameserver, which loads its deployment context from the edgegap API on boot,

and connects to our NATS instance in order to lookup session information. 



### bevygap_shared



Shared code for some protocol and NATS stuff, used between the matchmaker and gameserver.



### nats



[NATS](https://nats.io/) is the shared state and messaging backend between our various components.



### edgegap-client



Autogenerated client for the edgegap API using `openapi-generator`. See `gen-edgegap-client.sh`.



### bevy_nfws



a basic bevy websocket client, used to talk to the matchmaker.



## NOTES / TODO



probably want to prefix all NATS subjects/buckets with the edgegap app name or something, so that

multiple apps on edgegap can share the nats instance without conflicts.



should probably be restricted by the nats creds



# WebTransport custom certificate requirements



https://w3c.github.io/webtransport/#dom-webtransportoptions-servercertificatehashes



https://w3c.github.io/webtransport/#verify-a-certificate-hash



Strict cert requirements, we autogenerate one on boot and report the digest to the client, so

as long as the server doesn't stay up for more than 14 days, we're fine.



Chrome can't do CORS to http://localhost from http://lan-machine it seems, lan-machine would need to serve https.

https://stackoverflow.com/questions/66534759/cors-error-on-request-to-localhost-dev-server-from-remote-site



Access to fetch at 'http://127.0.0.1:3000/wannaplay' from origin 'http://lan-machine:8008' has been blocked by CORS policy: The request client is not a secure context and the resource is in more-private address space `local`.



## TODO



add httpd to ly servers that respond like the MM, generating a cert etc?

httpd example from bevy_remote:

https://github.com/bevyengine/bevy/blob/main/crates/bevy_remote/src/http.rs



move cert gen to LY?



implement the ConnectionRequestHandler properly to reject invalid connections



move matchmaker bevy/http bits into matchmaker crate too? flag to run bemw server and mm service in one binary, using a thread for mm?



proto id and ly pkey needed in docker-compose for MM stuff too, perhaps a move to a standard `lightyear.env` file which lightyear itself reads too? could default to sane zeros defaults if missing, for dev.



#### edgegap notes



* env vars limited to 255 bytes. hacky util script added to pass ca_contents as docker runtime arg

* can't use `latest` tag for container images, it's cached aggressively.