Transactions are not recorded for service

[pawan-1999]

Hi Team,

Transactions are not recorded for service but we can see the metrics

When we see the overview of the service we cannot see any data for that service but the name and entry is been added to the kibana UI. also I can see the metrics of that service. I want to trace the transactions for the service but it is not logged.

Steps to reproduce the behavior:

1. Using the below hello world code (https://medium.com/@adnanrahic/hello-world-app-with-node-js-and-express-c1eb7cfa8a30)

const express = require('express')
const app = express()

// Add this to the VERY top of the first file loaded in your app
var apm = require('elastic-apm-node').start({

// Override the service name from package.json
// Allowed characters: a-z, A-Z, 0-9, -, _, and space
serviceName: 'test-nodejs-app',

// Use if APM Server requires a secret token
secretToken: '',

// Set the custom APM Server URL (default: http://localhost:8200)
serverUrl: 'http://apm-server.com:8200',

capture_body: 'all',

// Set the service environment
environment: 'test'
})
app.get('/', (req, res) => res.send('Hello World!'))
app.listen(3000, () => console.log('Server ready'))

2. Then curl http://localhost:3000
3. Then I got the entry of the service on Kibana UI in APM.
4. But I cannot see any transactions or any other overview just I can see the metrics for that service

Expected behavior

It should show the transaction when I hit on http://localhost:3000

Environment

• OS: Linux
• Node.js version: v16.13.1
• APM Server version: apm-server version 7.17.9 (amd64), libbeat 7.17.9 [71a8b4c241eb5b4609862c8354d2aa2270f6c568 built 2023-01-31 04:33:06 +0000 UTC]
• Agent version: 3.46.0

How are you starting the agent? (please tick one of the boxes)

• Using this: Calling agent.start() directly (e.g. require('elastic-apm-node').start(...))

package.json dependencies:

  "dependencies": {
    "elastic-apm-node": "^3.46.0",
    "express": "^4.18.2",
    "http-errors": "^2.0.0"
  }
}

Thanks & Regards
Pawan Gupta

[trentm]

Hi @pawan-1999. Thanks for the question.

The issue here is that you are starting the APM agent after Express has already been loaded. For the APM agent to be able to instrument the express module, it needs to be started before require('express'). So if you change your script to something like this, it should work:

// Add this to the VERY top of the first file loaded in your app
var apm = require('elastic-apm-node').start({
    serviceName: 'test-nodejs-app',
    secretToken: '',
    serverUrl: 'http://apm-server.com:8200',
    capture_body: 'all',
    environment: 'test'
})

const express = require('express')
const app = express()
app.get('/', (req, res) => res.send('Hello World!'))
app.listen(3000, () => console.log('Server ready'))

https://www.elastic.co/guide/en/apm/agent/nodejs/current/starting-the-agent.html documents the issue with starting the APM agent too late.

We have an older issue to try to automatically warn about this kind of situation: #2578
I hope to implement that soon.

a separate note

This is unrelated, but a separate warning that you have the captureBody config var (https://www.elastic.co/guide/en/apm/agent/nodejs/current/configuration.html#capture-body) incorrectly spelled as capture_body. You'll need captureBody: 'all' for that to work.

Cheers.

[pawan-1999]

Thanks for helping. it worked and also thanks for adding it up in the document.