Tracing an ExpressJS Application

Recap.dev provides two levels of tracing: basic tracing and function-level tracing

Basic tracing collects request, response and error information, logs and provides a timeline of external resource access (databases, http endpoints, external services) of your unit (basically, endpoint or handler).

Function-level tracing also adds timings of the individual function calls to the timeline.

Setting up a Basic Tracing

1. Install recap.dev client library

yarn add @recap.dev/client

or

npm i --save @recap.dev/client

2. Wrap your express application with recap.dev tracing

import { traceExpress, tracer, captureConsoleLogs } from '@recap.dev/client'

import express from 'express'

traceExpress(express)

captureConsoleLogs()

const app = express()

const port = 3000

app.get('/trace-http-request', async (req, res) => {

tracer.setUnitName('dev-get-cat-facts')

const fact = await catFactsService.getFact()

res.json(fact)

})

Note the captureConsoleLogs() call which will automatically collect console.log logs for your trace.

3. Add tracer.setUnitName calls inside your handlers with appropriate names of your handlers.

4. Set the RECAP_DEV_SYNC_ENDPOINT environment variable to point at your recap.dev server's sync endpoint, for example:

http://recap-dev.company.com:8080/traces

Check out an example project here.

Setting up a Function-level Tracing

Click here to learn how to set up the function-level tracing for your application.