Add Backend Health Check Endpoint

[tgrunnagle]

Summary

This PR implements a standard health check endpoint at /health for the go-towerfall backend server, enabling better monitoring, orchestration, and operational visibility.

Closes: #108

Changes

New Endpoint: GET /health

Added a new health check endpoint that returns a simple JSON response indicating server health status:

{
  "status": "ok",
  "timestamp": "2026-01-25T20:22:28Z"
}

Implementation Details

1. Response Type (http_types.go:75-79)

   • Added HealthCheckResponse struct with status and timestamp fields

2. Request Handler (http_handlers.go:999-1028)

   • Implemented HandleHealth handler following existing backend patterns
   • Accepts GET requests only (returns 405 for other methods)
   • Supports CORS preflight (OPTIONS requests)
   • Returns 200 OK with JSON response containing status and UTC timestamp

3. Route Registration (main.go:16)

   • Registered /health route in main server initialization
   • Positioned before other endpoints for clarity

Design Decisions

• Path Choice: /health (industry standard) instead of /api/health

  • Used by Kubernetes liveness/readiness probes
  • Standard for AWS ELB/ALB, GCP Load Balancers, Azure Load Balancers
  • Separates operational endpoints from business API

• No Authentication: Health checks are publicly accessible for monitoring tools

• Simple Response: Returns minimal data (status + timestamp) for fast responses

• CORS-Enabled: Supports cross-origin requests with proper headers

Testing

Verified the endpoint works correctly:

✓ GET /health returns 200 OK with valid JSON response
✓ OPTIONS /health returns 200 OK with CORS headers (preflight support)
✓ POST /health returns 405 Method Not Allowed with error message
✓ Backend builds successfully without errors

Use Cases

This endpoint enables:

• Container orchestration health checks (Kubernetes, Docker, ECS)
• Load balancer health monitoring (AWS, GCP, Azure)
• CI/CD pipeline health verification
• Monitoring and alerting systems
• Development/debugging operational status checks