@openstatus/health-nats

NATS probe for @openstatus/health. Flushes a NatsConnection — one PING / PONG round trip with the server — and fails the check when the server does not answer or the connection has been closed.

deno add jsr:@openstatus/health jsr:@openstatus/health-nats
npm install @openstatus/health @openstatus/health-nats

import { connect } from "@nats-io/transport-node";
import { createHealthHandler } from "@openstatus/health";
import { natsProbe } from "@openstatus/health-nats";

const nc = await connect({ servers: env.NATS_URL });

Deno.serve(
  createHealthHandler({ probes: [natsProbe({ connection: nc })] }),
);

Reuse the connection your application already holds: NATS clients keep one multiplexed connection per process and reconnect on their own, so the probe reports what your publishers and subscribers actually see. While the client is reconnecting, flush() waits until the server is back — set timeoutMs to bound that. Any of the official clients works: @nats-io/transport-node, @nats-io/transport-deno, the websocket transport and the legacy nats package all expose the same flush() and isClosed().

natsProbe({
  connection: nc,
  // optional overrides from the Probe contract
  name: "events",
  critical: true,
  timeoutMs: 1000,
  skip: () => env.NATS_URL == null,
});

Non-critical by default: messaging usually carries background work, so an outage degrades the report instead of taking the service out of rotation. Set critical: true when requests cannot complete without publishing.

The connection is typed structurally as { flush(), isClosed?() }, so the NATS packages are optional peer dependencies for their types only and the probe adds no runtime import of them. The factory throws ProbeConfigError at construction when the connection has no flush().

About openstatus

openstatus is the open-source uptime monitoring and status page platform. This package is part of @openstatus/health, the /health endpoints behind openstatus's own services, extracted so any JavaScript server can expose one. Point an openstatus monitor at the endpoint and assert on status in the body to be alerted on degraded before it becomes unhealthy.

Source: github.com/openstatusHQ/health. Issues and PRs welcome.

License

MIT