Implement Comprehensive Deep Health Check Diagnostic Endpoint

[Cjay-Cyber-2]

Description

Operational visibility requires a deep health check endpoint (GET /health/deep) that assesses backend subsystems including PostgreSQL connectivity via Prisma, Stellar Horizon RPC responsiveness, and worker processing state before reporting overall node status.

Context & Requirements

• Endpoint location: GET /health/deep in src/routes/health.ts.
• Checks required:
  • Database: Simple query ping via Prisma (prisma.$queryRaw).
  • Stellar Horizon: Fetch latest ledger sequence or network root endpoint response time.
  • Environment/Worker: Check uptime and configuration state.
• Response must return status 200 OK if all critical services respond, or 503 Service Unavailable if key dependencies fail.

Acceptance Criteria

• Register GET /health/deep route in src/routes/health.ts.
• Implement asynchronous checks for database ping and Horizon RPC connectivity.
• Measure latency (in milliseconds) for each dependency check.
• Return JSON payload containing subsystem statuses, latencies, and overall health boolean.
• Respond with HTTP status 503 when critical checks (DB or Horizon) fail.
• Add unit and integration tests covering normal operation and subsystem failure scenarios.

Implementation Guidance

• Keep individual check timeouts reasonable (e.g., 3-5 seconds) so health probes do not hang.
• Avoid exposing sensitive operational secrets or internal connection strings in response output.
• Follow Fastify schema definitions for response serialization.

Testing & Validation

• Run tests with npm test.
• Validate that mock DB or Horizon failures correctly result in a 503 response code.

Submission Guidelines

• Open a PR that includes "Closes #".
• Ensure task assignment before starting work.
• Maintain existing code structure and linting requirements.

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Wave complexity: Medium

[chiemezie1]

@chiemezie1 has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hello, I have reviewed the issue and understand what needs to be done.

I would appreciate being assigned to it.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @chiemezie1 to this issue.