API reference

backend({ gateway }) configures Layeron’s public Gateway runtime for CORS, request ids, trace headers, and Gateway product logs.

Import

import { backend } from "@layeron/core"

Create a Layeron backend app.

backend(options: BackendOptions): BackendApp

Options accepted by backend({ gateway }).

Field	Type	Description
`cors`	`GatewayCorsConfig \| undefined`	CORS policy for Gateway responses and preflight requests.
`logs`	`GatewayLogConfig \| undefined`	Gateway product log controls.
`defaultAuth`	`RouteAuthPolicy \| undefined`	Default route auth policy when a route omits auth.
`requestIdHeader`	`string \| undefined`	Incoming header used as the request id. Defaults to x-request-id.
`responseRequestIdHeader`	`string \| undefined`	Response header that carries the request id. Defaults to x-layeron-request-id.
`traceHeader`	`string \| undefined`	Incoming trace header stored in runtime context. Defaults to traceparent.

Gateway CORS policy.

Field	Type	Description
`origins`	`string[] \| undefined`	Allowed request origins.
`methods`	`HttpMethod[] \| undefined`	Methods allowed by CORS preflight.
`requestHeaders`	`string[] \| undefined`	Request headers allowed by CORS preflight.
`responseHeaders`	`string[] \| undefined`	Response headers exposed to browsers.
`credentials`	`boolean \| undefined`	Whether matching origins receive Access-Control-Allow-Credentials.
`maxAgeSeconds`	`int32 \| undefined`	Access-Control-Max-Age value in seconds.

Gateway product log controls.

Field	Type	Description
`level`	`ObservabilitySeverity \| undefined`	Minimum Gateway product log level.
`request`	`boolean \| undefined`	Whether request lifecycle logs are emitted.
`cors`	`boolean \| undefined`	Whether CORS decision logs are emitted.
`routeMatch`	`boolean \| undefined`	Whether route matching diagnostics are emitted.
`errors`	`boolean \| undefined`	Whether normalized Gateway error logs are emitted.
`includeHeaders`	`string[] \| undefined`	Header allowlist for log attributes.
`redactHeaders`	`string[] \| undefined`	Additional headers to redact when included.
`sampling`	`Layeron.Observability.SamplingPolicy \| undefined`	Sampling policy for Gateway logs.

Options accepted by backend().

Field	Type	Description
`project`	`string`	Immutable project slug.
`gateway`	`GatewayConfig \| undefined`	Gateway runtime settings.

Layeron backend app returned by backend().

Field	Type	Description
`project`	`string`	Project slug.
`gateway`	`GatewayConfig \| undefined`	Gateway runtime settings.