@stainlessdev/xray-express

Express integration for Stainless X-ray request logging. Provides a middleware that wraps Express requests and responses.

Install

``sh
pnpm add @stainlessdev/xray-express
`

Basic usage

`ts
import express from 'express';
import { createEmitter } from '@stainlessdev/xray-express';
import { getXrayContext } from '@stainlessdev/xray-node';

const app = express();

const xray = createEmitter({
serviceName: 'my-service',
endpointUrl: 'http://localhost:4318',
});

app.use(xray);

app.use((req, _res, next) => {
const ctx = getXrayContext(req);
ctx?.setUserId('user-123');
next();
});

app.get('/', (_req, res) => {
res.send('ok');
});
`

The middleware also attaches the context to req.xray and res.locals.xray for convenience.

Request IDs and response headers

X-ray will auto-generate a request ID and inject it into your response headers under the configured name (requestId.header, default request-id, emitted as Request-Id) if the header is missing. If you set your own request ID first (via options.requestId or by setting the response header yourself), X-ray preserves it and does not overwrite the header.

Configuration

createEmitter(config, options?) accepts XrayRuntimeConfig (config) and WrapOptions (per-request defaults):

- serviceName (required)
- endpointUrl (required; falls back to STAINLESS_XRAY_ENDPOINT_URL when omitted; explicit endpointUrl wins)
- environment, version, logger, logLevel
- exporter: endpointUrl, headers, timeoutMs, spanProcessor, instance (custom SpanExporter)
- capture: request/response headers and bodies
- redaction: headers/query/body JSON-path redaction
- requestId: header name to read/write
- route: normalization options

Adapter options (WrapOptions)

- route: override the route name for the request
- requestId: explicit request ID to use (prevents auto-generation)
- capture: per-request capture overrides
- redaction: per-request redaction overrides
- onRequest(ctx), onResponse(ctx, log), onError(ctx, err) hooks

Advanced usage

If you already have an XrayEmitter instance, use createExpressMiddleware(xray, options)` to create middleware.

Notes

- This package depends on OpenTelemetry packages as peer dependencies.
- Node.js >= 20 is required.