Responses and HTTP

Rollup status

Overall HealthResponse.status is computed from all check results for that probe:

1. Any fail → fail (unless remapped by onFail.treatAs on that check).
2. Else any degraded → degraded.
3. Else ok.

Override with rollup.computeStatus(results) for custom rules.

HTTP status

Response status (HTTP code) is derived from the rolled-up health status and your config:

• Any check with status === "fail" and onFail.httpStatus set → that value is returned (first matching check in config order wins among failed checks with a custom status).
• Else if rollup is fail: defaults.onFail.httpStatus or 503.
• Else if rollup is degraded: defaults.onDegraded.httpStatus or 200.
• Else 200.

onFail.treatAs changes the check status used for rollup and the JSON/text body; combine with onFail.httpStatus or defaults when you need a specific HTTP code.

Output

output on the root config:

• format: "json" (default) or "text".
  • JSON: Content-Type: application/json, body is JSON.stringify of HealthResponse.
  • Text: Content-Type: text/plain, human-readable lines (status:, then each check with latency and optional error).
• exposeError: Default true. If false, the error field is omitted from each check in the payload.

Public API overview

Runtime

• createHealthKit(config) → HealthKit
• HealthKit: start(), stop(), handleRequest(req), handleLiveness(), handleReadiness()

Types

• HealthkitConfig, CheckConfig, HealthAdapter, AdapterResult, CheckResult, HealthResponse
• CheckStatus, CheckType, RollupConfig, OutputConfig, DefaultsConfig
• AgnosticRequest, AgnosticResponse

The canonical type definitions and any future additions live in the healthzkit package under packages/healthzkit in this monorepo.