The Multi-Snake project was created to support the talk Processes & Grains A Journey in Orleans at Code BEAM Europe 2022 on 19 May 2022.

A copy of the deck can be found here.

A deployed version on Fly.io is available at https://snake-web.fly.dev.

• Classic snake game.
• With responsive design based on SVG rendition of the game board.
• With example Dockerfile for deployment on Fly.io or other cloud providers, encapsulating full Elixir releases with fully generated and digested Phoenix assets.
• With custom Cowboy 2 integration, working for both Plug-based and WebSocket-based traffic, allowing seamless integration of multiple Phoenix Endpoints in different applications, including fully working Phoenix Sockets.
• With Phoenix LiveView integration, to provide the user interface, including event handling.
• With Phoenix Presence integration, to count live players.
• With custom esbuild integration, allowing straightforward integration of NPM modules, such as bootstrap.
• With libcluster integration, to provide intra-node clustering via Erlang Distribution.
• With erleans & horde integration, to showcase available strategies that can be used to build backends, alongside with straightforward implementation of snapshots (checkpoints) to ensure continuity of processing.

To run the code:

1. Clone the repository.
2. Install the appropriate Erlang, Elixir and Node.js verisons via asdf (see .tool-versions).
3. Run mix deps.get.
4. Run mix ecto.setup.
5. Run ./bin/run.
6. Visit https://localhost:4000.
7. For additional nodes, run ./bin/console.

The Multi-Snake application is an umbrella application with the following applications:

• snake: Holds the core game logic and backends.
• snake_data: Holds Ecto Repo and all migrations.
• snake_environment: Holds clustering and endpoint configuration logic.
• snake_proxy: Holds a connection proxy allowing numerous Phoenix apps to be hooked.
• snake_web: Holds the main Web application containing a LiveView interface.

Within apps/snake/config/config.exs, the appropriate Backend can be selected:

config :snake,
  backend_module: Snake.Game.Backend.HordeStatem 

Where 3 distinct backends are available:

• Snake.Game.Backend.ErleansGrain, implemented as a stateful Erleans Grain, preferring local activation.

• Snake.Game.Backend.HordeServer, implemented as a GenServer registered under a distributed supervisor offered by Horde.

• Snake.Game.Backend.HordeStatem, implemented as a GenStateMachine (Elixir wrapper of gen_statem) registered under a distributed supervisor offered by Horde.

Via Prepared Script:

$ flyctl ssh console
> /app/migrate.sh