Tech World Game Server

WebSocket server for Tech World that manages player connections and broadcasts movement/presence messages to all connected clients.

Built using shelf and shelf_web_socket.

Features

• Manages WebSocket connections for multiple players
• Broadcasts player presence (arrivals/departures)
• Relays player movement paths to other connected clients
• SSL/TLS support for secure WebSocket connections (WSS)

Prerequisites

• Dart SDK 3.0.0+
• SSL certificates for production deployment

Setup

dart pub get

Running

Development

dart run bin/server.dart

The server requires SSL certificates at /app/cert.pem and /app/key.pem. For local development, you may need to modify these paths or generate self-signed certificates.

VS Code Launch Configuration

{
  "name": "ws_game_server",
  "request": "launch",
  "type": "dart",
  "program": "bin/server.dart"
}

Testing Connection

curl -i -N -H "Connection: Upgrade" -H "Upgrade: websocket" -H "Host: localhost" -H "Origin: http://localhost" -H "Sec-WebSocket-Version: 13" -H "Sec-WebSocket-Key: SGVsbG8sIHdvcmxkIQ==" http://localhost:8080

Testing

dart test

Architecture

• bin/server.dart: Entry point, creates shelf server with SSL on port 443
• lib/client_connections_service.dart: Manages WebSocket connections, handles message routing
• lib/locator.dart: Service locator for dependency injection

Message Flow

1. Client connects via WebSocket
2. Client sends arrival message with user info
3. Server stores connection and broadcasts other_users to all clients
4. Server relays player_path messages to other connected clients
5. On disconnect, server broadcasts updated other_users list

Deployment

Deploying to GCP Compute Engine

The CI/CD pipeline automatically deploys to a Compute Engine VM when you push a tagged commit:

git tag v1.0.0 && git push --tags

How it works:

1. Push a tagged commit
2. GitHub Actions builds the Docker image and pushes to Artifact Registry
3. The workflow SSHs into the VM and updates the running container

VM Details:

• Instance: instance-20251007-053239
• Zone: us-central1-a
• Machine type: e2-micro

Required GCP Permissions for GitHub Actions service account:

• roles/artifactregistry.writer - push images to Artifact Registry
• roles/compute.instanceAdmin.v1 - SSH into the VM
• roles/iap.tunnelResourceAccessor - tunnel through IAP (if enabled)

Setup References:

• Setup Workload Identity Federation for GitHub Actions
• Create a Compute Engine VM

Dependencies

• shelf: HTTP server framework
• shelf_web_socket: WebSocket support for shelf
• web_socket_channel: WebSocket abstractions
• tech_world_networking_types: Shared message types