Add /ready endpoint for comprehensive service readiness checking

[Copilot]

This PR adds a new /ready endpoint that provides a simple way to determine when the Stellar Quickstart image is fully ready for use, addressing the issue where users need to write custom scripts to test readiness.

Changes

New /ready Endpoint

• HTTP 200 when all services are ready for use
• HTTP 503 when any service is not ready
• JSON response with detailed service status

Example response when ready:

{
  "status": "ready",
  "services": {
    "stellar-core": "ready",
    "horizon": "ready",
    "horizon_health": {
      "database_connected": true,
      "core_up": true,
      "core_synced": true
    },
    "stellar-rpc": "ready"
  }
}

Implementation Details

• Auto-detection: Automatically detects which services are actually running
• Smart health checks: Uses appropriate health check methods for each service:
  • stellar-core: /info endpoint
  • horizon: Root endpoint + ingestion status + built-in /health
  • stellar-rpc: getHealth JSON-RPC method
• Non-conflicting: Works alongside existing Horizon /health endpoint
• Comprehensive: Only reports "ready" when ALL detected services are functioning

Architecture

• Python-based service running on internal port 8004
• nginx proxy routes /ready through main port 8000
• supervisord management ensures service reliability
• Integrated with start script for proper deployment

Documentation

• Added comprehensive endpoint documentation with examples
• Updated ports table to include readiness service
• Explained difference between /health (Horizon-specific) and /ready (all services)

Testing

Verified working with test container running --local --enable core,horizon,rpc:

• ✅ All three services detected and reported as ready
• ✅ HTTP 200 status when ready
• ✅ Proper JSON response format
• ✅ Original /health endpoint continues to work
• ✅ Test script passes

This eliminates the need for users to write custom scripts to test multiple service endpoints individually.

Fixes #683.

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[leighmcculloch]

Can the endpoint be /health?

[leighmcculloch]

It's fine for the /health endpoint to sit over Horizon's health endpoint.

[sagpatil]

@copilot can you rename the endpoint to /health

[Copilot]

@copilot can you rename the endpoint to /health

Done! Renamed the endpoint from /ready to /health as requested. The changes include updating nginx configuration, Python service, documentation, and tests. Commit f4e78bb.

[leighmcculloch]

@sagpatil @fnando There was a discussion offline at https://stellarfoundation.slack.com/archives/C06KTGUULUF/p1752530679018619 where I shared the idea that we think about the root URL as the health endpoint. For the most part that's what it is for horizon historically, and as a user it's where I go when I want to see that the image is working. When Horizon is removed from being by default on, we should rethink the root path and what it serves, and a status / health like endpoint, like what horizon does today, could make sense.