Winston

Ship Winston log records to AxonPush as OpenTelemetry-shaped app.log events. Winston is the legacy Node.js logging standard, still widely used.

[!TIP] Non-blocking by default (v0.0.2+)

The transport pushes each record onto a bounded in-memory queue and drains it from a single background task. Call transport.flushAxonPush(timeoutMs?) at known checkpoints to guarantee delivery, or use flushAfterInvocation. Pass mode: "sync" for blocking publishes. See the Pino page for the Lambda flush pattern — flushAfterInvocation works with the Winston transport too.

Installation

npm install @axonpush/sdk winston winston-transport

Setup

The factory returns a Promise<Transport> because winston-transport is lazily imported (it’s an optional peer dep). Await it before building the logger:

import winston from "winston";
import { AxonPush } from "@axonpush/sdk";
import { createAxonPushWinstonTransport } from "@axonpush/sdk/integrations/winston";

const client = new AxonPush({
  apiKey: process.env.AXONPUSH_API_KEY!,
  tenantId: process.env.AXONPUSH_TENANT_ID!,
});

const axonpushTransport = (await createAxonPushWinstonTransport({
  client,
  channelId: 1,
  serviceName: "my-api",
  environment: "production",
})) as winston.transport;

const log = winston.createLogger({
  level: "info",
  transports: [new winston.transports.Console(), axonpushTransport],
});

Usage

log.info({ message: "user signed in", userId: 42, method: "oauth" });
log.warn({ message: "rate limit approaching", endpoint: "/api/search", remaining: 3 });
log.error({ message: "downstream timeout", endpoint: "/api/search", elapsedMs: 5000 });

Flushing and closing

interface AxonPushTransport {
  flushAxonPush(timeoutMs?: number): Promise<void>;
  close(): void;
}

await (axonpushTransport as unknown as AxonPushTransport).flushAxonPush(1000);

close() is called by Winston’s own shutdown lifecycle when you call log.close(); it also runs automatically via the module-level beforeExit hook at process shutdown.

Level mapping

Winston level	OTel severityNumber	severityText
silly, trace	1	TRACE
debug, verbose	5	DEBUG
http, info	9	INFO
notice	11	INFO
warn, warning	13	WARN
error	17	ERROR
crit, alert, emerg, fatal	21	FATAL

Events

Field	Value
identifier	"winston"
eventType	"app.log"
payload.body	The message field
payload.attributes	All non-standard fields from the Winston info object
payload.resource	service.name, service.version, deployment.environment (if configured)