Liveness probe

GET

/healthz

const url = 'https://example.com/healthz';
const options = {method: 'GET'};

try {
  const response = await fetch(url, options);
  const data = await response.json();
  console.log(data);
} catch (error) {
  console.error(error);
}

curl --request GET \
  --url https://example.com/healthz

Returns 200 OK with a fixed shape. No authentication required. Used by Docker, Kubernetes, and reverse proxies to decide whether the backend is up. Has zero dependencies — does not touch the database, the printer queue, SNMP, or any integration. sse_active_subscribers reflects the current EventBus subscriber count; zero means no live SSE clients or the bus is uninitialised.

Responses

200

Successful Response

application/json

Healthz

Response body of /healthz.

Intentionally minimal — no dependencies, no configuration, no PII. Container orchestrators check the HTTP status and read the JSON for a quick version sanity-check; ops use the build-info fields to confirm which image is running without digging through docker inspect.

Frozen so callers can’t accidentally mutate the response model in-place (the same immutability discipline we apply to dataclasses — see docs/learnings/code-review-patterns.md).

object

build_date

required

Build Date

string

repository

required

Repository

string

revision

required

Revision

string

sse_active_subscribers

Sse Active Subscribers

integer

status

required

Status

string

version

required

Version

string

Example

{
  "sse_active_subscribers": 0
}