OpenTelemetry Koa Instrumentation for Node.js

[![NPM Published Version][npm-img]][npm-url]
[![Apache License][license-image]][license-image]

This module provides automatic instrumentation for the Koa module, which may be loaded using the @opentelemetry/sdk-trace-node package and is included in the @opentelemetry/auto-instrumentations-node bundle.

If total installation size is not constrained, it is recommended to use the @opentelemetry/auto-instrumentations-node bundle with https://www.npmjs.com/package/@opentelemetry/sdk-node" class="text-primary hover:underline" target="_blank" rel="noopener noreferrer">@opentelemetry/sdk-node for the most seamless instrumentation experience.

Compatible with OpenTelemetry JS API and SDK 1.0+.

Status

| Maturity | Component Owner | Compatibility |
|----------------------------------------------------|-------------------------------------------------------|-----------------------|
| Unmaintained | N/A | API 1.0+
SDK 1.0+ |

Installation

``bash
npm install --save @opentelemetry/instrumentation-koa
`

$3

- koa versions >=2.0.0 <4
- @koa/router versions >=8.0.0

Usage

OpenTelemetry Koa Instrumentation allows the user to automatically collect trace data and export them to their backend of choice, to give observability to distributed systems.

`js
const { NodeTracerProvider } = require('@opentelemetry/sdk-trace-node');
const { registerInstrumentations } = require('@opentelemetry/instrumentation');
const { KoaInstrumentation } = require('@opentelemetry/instrumentation-koa');

const provider = new NodeTracerProvider();
provider.register();

registerInstrumentations({
instrumentations: [
new KoaInstrumentation(),
],
});
`

See examples/koa for a short example using both Koa and @koa/router.

Note that generator-based middleware are deprecated and won't be instrumented.

$3

| Options | Type | Example | Description |
| ------------------ | ----------------------------------- | -------------------- | -------------------------------------------------------------------------------------------------------- |
| ignoreLayersType | KoaLayerType[] | ['middleware'] | Ignore layers of specified type. |
| requestHook | KoaRequestCustomAttributeFunction | (span, info) => {} | Function for adding custom attributes to Koa middleware layers. Receives params: Span, KoaRequestInfo. |

ignoreLayersType accepts an array of KoaLayerType which can take the following string values:

- router,
- middleware.

#### Using requestHook

Instrumentation configuration accepts a custom "hook" function which will be called for every instrumented Koa middleware layer involved in a request. Custom attributes can be set on the span or run any custom logic per layer.

NOTE: KoaRequestInfo.context and KoaRequestInfo.middlewareLayer are typed as any. If you want type support make sure you have @types/koa and @types/koa__router installed then you can use the following type definitions:

`typescript
import { KoaInstrumentation } from "@opentelemetry/instrumentation-koa"
import type { Middleware, ParameterizedContext, DefaultState } from 'koa';
import type { RouterParamContext } from '@koa/router';

type KoaContext = ParameterizedContext;
type KoaMiddleware = Middleware;

const koaInstrumentation = new KoaInstrumentation({
requestHook: function (span: Span, info: KoaRequestInfo) {
span.setAttribute(
'http.method',
info.context.request.method
)
}
});
`

Koa Packages

This package provides automatic tracing for middleware added using either the core koa package or the @koa/router` package.

Useful links

- For more information on OpenTelemetry, visit:
- For more about OpenTelemetry JavaScript:
- For help or feedback on this project, join us in [GitHub Discussions][discussions-url]

License

Apache 2.0 - See [LICENSE][license-url] for more information.

[discussions-url]: https://github.com/open-telemetry/opentelemetry-js/discussions
[license-url]: https://github.com/open-telemetry/opentelemetry-js-contrib/blob/main/LICENSE
[license-image]: https://img.shields.io/badge/license-Apache_2.0-green.svg?style=flat
[npm-url]: https://www.npmjs.com/package/@opentelemetry/instrumentation-koa
[npm-img]: https://badge.fury.io/js/%40opentelemetry%2Finstrumentation-koa.svg