Healthcheck Core guides

Define a dependency check

import { defineHealthCheck } from "@nexload-sdk/healthcheck";

const database = defineHealthCheck({
  name: "database",
  component: "postgres",
  scopes: ["readiness", "diagnostics"],
  critical: { readiness: true, diagnostics: false },
  timeoutMs: 1_000,
  async run(ctx) {
    await db.query("select 1", { signal: ctx.signal });
    return { status: "ok", metrics: { up: true } };
  },
});

Honor ctx.signal, use stable error codes, and keep details free of credentials. Put checks for recoverable dependencies in readiness. Liveness should normally test the process itself.

Call health.setShutdownState(true, reason) before draining traffic. shutdownCheck() then makes liveness and readiness unhealthy.

Use stringifyHealthJson(report, { includeDetails: false, redact: true }) for public output. Prefer exporter packages for monitoring rather than scraping diagnostic JSON.