Node Agent

Scout’s Node.js agent instruments popular libraries to capture middleware timing, SQL queries, template rendering, HTTP calls, and more. The package is called @scout_apm/scout-apm on npm. Source code and issues can be found on our scout_apm_node GitHub repository.

Requirements

@scout_apm/scout-apm requires:

• Node.js 18+
• A POSIX operating system, such as Linux or macOS.

Instrumented Libraries

Scout automatically instruments the following libraries when you call init():

Web Frameworks

• Express 4.x+
• NestJS 10.x+

Databases

• PostgreSQL via pg
• MySQL via mysql and mysql2
• MongoDB via mongodb (v4+)
• Prisma via @prisma/client (Prisma 6+)

Caching

• Redis via ioredis or redis (node-redis v4+)

HTTP Clients

• Node.js built-in http and https modules
• Native fetch / undici (Node.js 18+, via diagnostics_channel)

Templating

• EJS
• Mustache
• Pug

You can instrument your own code via custom instrumentation. You can suggest additional libraries you’d like Scout to instrument on GitHub.

Initialization

Scout hooks into Node’s module system to instrument libraries as they load. The recommended pattern is a dedicated scout.js (or scout.ts) file that calls init() before any other code runs:

# No code changes needed — use the preload flag
node --require @scout_apm/scout-apm/preload app.js

Or create a scout.js and require it first:

// scout.js
const { init } = require("@scout_apm/scout-apm");
init({ name: "My App", key: process.env.SCOUT_KEY, monitor: true });

See the Setup guide for the complete initialization pattern for your framework.

Updating to the Newest Version

npm install @scout_apm/scout-apm@latest

The package changelog is available here.