No local variables w/ Node 14 and sentry-node 7.43.0

[jrocketfingers]

Is there an existing issue for this?

• I have checked for existing issues https://github.com/getsentry/sentry-javascript/issues
• I have reviewed the documentation https://docs.sentry.io/
• I am using the latest SDK release https://github.com/getsentry/sentry-javascript/releases

How do you use Sentry?

Sentry Saas (sentry.io)

Which SDK are you using? If you use the CDN bundles, please specify the exact bundle (e.g. bundle.tracing.min.js) in your SDK setup.

@sentry/node

SDK Version

7.43.0

Framework Version

No response

Link to Sentry event

https://core-org.sentry.io/issues/4017701628/?project=4504862651318272

SDK Setup

Sentry.init({
dsn: 'Correct DSN, event appears successfully',
includeLocalVariables: true,
});

Steps to Reproduce

I'm literally just trying to get local variables on my NodeJS app events, and I've created a complete dummy app to test them with the version of node I'm using in the production app, as well as benchmark the performance loss, if any.

Here's the whole code currently used to reproduce:

app.js:

const md5 = require('md5');
const Sentry = require('@sentry/node');

Sentry.init({
	dsn: 'MY DSN',
	//sampleRate: 5e-6,
	includeLocalVariables: true,
});

const { param1, param2 } = { param1: 'potato', param2: 'potato' };
const hash = md5(`${param1}${param2}`);
// Throw an error to trigger a 500 status response
throw new Error('An error occurred during hashing');

package.json:

{
  "name": "sentry-test",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "jest"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "@sentry/node": "^7.43.0",
    "md5": "^2.3.0",
  }
}

Node version: v14.21.2

Expected Result

Local variables shown, as per the example in the SDK update post.

Actual Result

No variables shown:

[jrocketfingers]

Collecting local vars of anonymous variables seems to be the problem.

Did I miss an aspect of the docs describing this behavior? When used with Express, route functions are usually anonymous, and I'd like to catch locals there as well.

[AbhiPrasad]

Hey @jrocketfingers, thanks for writing in!

Anonymous functions should be fine, you can test this by wrapping your code in a iife:

(() => {
  const { param1, param2 } = { param1: "potato", param2: "potato" };
  const hash = md5(`${param1}${param2}`);
  // Throw an error to trigger a 500 status response
  throw new Error("An error occurred during hashing");
})();

Of course wrapping in a plain func/arrow func works just as well

const run = () => {
  const { param1, param2 } = { param1: "potato", param2: "potato" };
  const hash = md5(`${param1}${param2}`);
  // Throw an error to trigger a 500 status response
  throw new Error("An error occurred during hashing");
};

run();

The problem seems to be when the error is thrown in the global lexical scope, I think we aren't accounting for that case properly. It might be that the objectid is undefined for this case. Backlogging because this is something we should investigate further, but if you figure anything out please share the details!

[AbhiPrasad]

Yeah when I run a debugger I get the following props on pause:

[
  {
    name: "module",
    value: {
      type: "object",
      className: "Module",
      description: "Module",
      objectId: "-3727568694531409572.1.38",
    },
    writable: true,
    configurable: true,
    enumerable: true,
    isOwn: true,
  },
  {
    name: "filename",
    value: {
      type: "string",
      value: "/Users/abhijeetprasad/sdk-demos/node/GH-7512-node-local-variables/index.js",
    },
    writable: true,
    configurable: true,
    enumerable: true,
    isOwn: true,
  },
  {
    name: "cached",
    value: {
      type: "undefined",
    },
    writable: true,
    configurable: true,
    enumerable: true,
    isOwn: true,
  },
  {
    name: "content",
    value: {
      type: "string",
      value: "const md5 = require(\"md5\");\nconst Sentry = require(\"@sentry/node\");\n\nSentry.init({\n  dsn: \"https://public@dsn.ingest.sentry.io/1337\",\n  //sampleRate: 5e-6,\n  includeLocalVariables: true,\n  debug: true,\n  beforeSend(event) {\n    event.exception.values[0].stacktrace.frames.forEach((frame) => {\n      console.log(frame.vars);\n    });\n    console.log(event.exception.values[0].stacktrace);\n    return null;\n    // return event;\n  },\n});\n\n// (() => {\n//   const { param1, param2 } = { param1: \"potato\", param2: \"potato\" };\n//   const hash = md5(`${param1}${param2}`);\n//   // Throw an error to trigger a 500 status response\n//   throw new Error(\"An error occurred during hashing\");\n// })();\n\n// const run = () => {\n//   const { param1, param2 } = { param1: \"potato\", param2: \"potato\" };\n//   const hash = md5(`${param1}${param2}`);\n//   // Throw an error to trigger a 500 status response\n//   throw new Error(\"An error occurred during hashing\");\n// };\n\n// run();\n\nconst { param1, param2 } = { param1: \"potato\", param2: \"potato\" };\nconst hash = md5(`${param1}${param2}`);\n// Throw an error to trigger a 500 status response\nthrow new Error(\"An error occurred during hashing\");\n",
    },
    writable: true,
    configurable: true,
    enumerable: true,
    isOwn: true,
  },
]

which gives me no indication of the local vars. Compare this to when I wrap in a function:

[
  {
    name: "param1",
    value: {
      type: "string",
      value: "potato",
    },
    writable: true,
    configurable: true,
    enumerable: true,
    isOwn: true,
  },
  {
    name: "param2",
    value: {
      type: "string",
      value: "potato",
    },
    writable: true,
    configurable: true,
    enumerable: true,
    isOwn: true,
  },
  {
    name: "hash",
    value: {
      type: "string",
      value: "3d8c3e934d10fd956c952e0b1b1fb61d",
    },
    writable: true,
    configurable: true,
    enumerable: true,
    isOwn: true,
  },
]

@timfish, familiar with what's going on here?

[timfish]

I'm not familiar with this but can take a look.

[jrocketfingers]

The thing is it initially failed to send locals from within an express route. While trying to come to the root of the issue, it seems I've accidentally whittled down the problem into a different one of global scope not being properly handled, that.

I'll retry with express and post back, but I take it express routes aren't in any way more special than a regular anonymous function?

EDIT:
Express catches exceptions, which required me to enable captureAllExceptions. Docs were kinda unclear (and misleading in the example that initializes new LocalVariables integration), but I made it work, so disregard this comment.

[jrocketfingers]

Hey @AbhiPrasad do you mind linking to a PR/version that fixes this? I'd love to upgrade to it in case it's already released, or follow its future release if possible.

[AbhiPrasad]

We actually ended up restricting LocalVariables to only work for Node 18+ due to Node standard library bugs with inspector and async hooks. See #7697 and nodejs/node#47406 for more details.

We then decided that prioritizing making local variables work for the global lexical scope was low priority, as 99% of the time there should be a function existing as the lexical scope, so closed this issue as a result. Sorry for not leaving a comment - that's my bad.

If we get more feedback around this we can always re-visit this and re-open!