Observability

Structured Logging

Pass a logger to createSearchFnServer to receive structured log events for every operation:

const server = await createSearchFnServer({
  adapter,
  logger: {
    info: (msg, ctx) => console.log(JSON.stringify({ level: "info", msg, ...ctx })),
    warn: (msg, ctx) => console.warn(JSON.stringify({ level: "warn", msg, ...ctx })),
    error: (msg, ctx) => console.error(JSON.stringify({ level: "error", msg, ...ctx })),
    debug: (msg, ctx) => console.debug(JSON.stringify({ level: "debug", msg, ...ctx })),
  },
});

Log Events

The server emits these event names:

request.start
request.end
request.error
authorization.denied
authorization.error
server.close

Log Fields

Each log event includes:

Field	Type	Description
`operation`	`string`	The action being performed (`search`, `index`, `remove`, etc.)
`adapter`	`string`	Adapter name (`memory`, `postgres`, `meilisearch`, etc.)
`durationMs`	`number`	Time taken for the operation in milliseconds
`status`	`number`	HTTP status code from the response
`success`	`boolean`	Whether the operation succeeded
`errorCode`	`string?`	Error code if the operation failed

Sensitive values are automatically redacted before logging. See Security for details.

Health Endpoint

GET /searchfn/status provides a readiness check for load balancers and monitoring:

{
  "ok": true,
  "result": {
    "adapter": "postgres",
    "capabilities": {
      "persistent": true,
      "searchAll": true,
      "fuzzy": true,
      "fieldBoosts": false
    },
    "uptimeMs": 84200
  }
}

Use this endpoint for:

Kubernetes readiness probes
Load balancer health checks
Monitoring dashboards

Failure Classification

Errors fall into five categories. Use these to build alerts and dashboards:

Category	Error codes	Cause	Action
Validation	`DFQL_INVALID`, `LIMIT_EXCEEDED`	Malformed request or exceeded limits	Fix client-side request construction
Authorization	`FORBIDDEN`	Auth callback denied access	Check credentials and permissions
Unsupported	`DFQL_UNSUPPORTED`	Adapter doesn't support the operation	Use a different adapter or remove unsupported options
Runtime	`INTERNAL`	Unexpected backend failure	Check backend health and logs
Cancellation	`DFQL_ABORTED`	Client cancelled the request	No action needed (expected behavior)

Alerting Recommendations

Alert on INTERNAL errors — these indicate backend problems that need investigation.
Monitor LIMIT_EXCEEDED rates — a spike may indicate a client bug or abuse.
Track durationMs percentiles — degrading latency can signal backend capacity issues.
Ignore DFQL_ABORTED — these are normal when users navigate away or cancel searches.