rezn-bbox

rezn-bbox is a black-box runtime observer for the Rezn orchestration system.

It monitors externally observable behavior—such as HTTP response time and status codes—and exposes a live event stream for Rezn to consume over WebSocket or SSE.

rezn-bbox does not require application instrumentation. It integrates with local proxies or probes to observe container behavior from the outside.

Features

• Observes HTTP behavior externally
• Captures response times, status codes, and request metadata
• Exposes observations via WebSocket or Server-Sent Events
• Designed for Rezn to connect as a live data consumer

Communication

rezn-bbox exposes a stream endpoint (e.g. ws://localhost:7878/metrics).

Each message contains a contract-relevant aggregate:

{
  "job": "auth-svc",
  "endpoint": "/health",
  "method": "GET",
  "window": "1m",
  "metrics": {
    "count": 242,
    "status_2xx": 240,
    "status_5xx": 2,
    "avg_duration_ms": 212.3,
    "p95_duration_ms": 289.7
  },
  "timestamp": 1723442399000
}

Rezn uses this data to evaluate postconditions and invariants declared in job contracts.

Contract Example (Rezn DSL)

job "auth-svc" {
  contract invariant "bbox.metrics['/health'].p95_duration_ms < 300"
  contract invariant "bbox.metrics['/health'].status_5xx == 0"
}

or

contract postcondition "bbox.avg_duration_ms < 250"

License

MPL 2.0