On Node 20: The requested module 'hot-shots' does not provide an export named 'StatsD'

[robaca]

We just try to upgrade our Node/ESM project to Node.js 20(.8.0). Without datadog, our services are running fine, but when adding the loader to the startup command via node --loader dd-trace/loader-hook.mjs ..., we get the following error (ignoring the warnings for now):

(node:186) ExperimentalWarning: `--experimental-loader` may be removed in the future; instead use `register()`:
--import 'data:text/javascript,import { register } from "node:module"; import { pathToFileURL } from "node:url"; register("dd-trace/loader-hook.mjs", pathToFileURL("./"));'
(Use `node --trace-warnings ...` to show where the warning was created)
14:31:41.764 ERROR    Error starting service
The requested module 'hot-shots' does not provide an export named 'StatsD'
file:///usr/src/app/libs/server/lib/core/metrics/createStatsdClient.js:1
import { StatsD } from 'hot-shots';
         ^^^^^^
SyntaxError: The requested module 'hot-shots' does not provide an export named 'StatsD'
    at ModuleJob._instantiate (node:internal/modules/esm/module_job:131:21)
    at async ModuleJob.run (node:internal/modules/esm/module_job:213:5)
    at async ModuleLoader.import (node:internal/modules/esm/loader:316:24)
    at async Cluster.startupMethod (file:///usr/src/app/lib/main/server/index.js:18:30)
    at async Cluster.initializeWorker ```

**Steps to reproduce**

- Create an empty project via `npm init`
- `npm install hot-shots`
- `npm install dd-trace`
- Create a `test.mjs` file with `import { StatsD } from 'hot-shots'`
- `node --loader dd-trace/loader-hook.mjs test.mjs`
- 
**Environment**

* **Operation system: MacOS / Debian Linux**
* **Node.js version: 20.8.0**
* **Tracer version: 4.16.0**
* **Agent version: -**
* **Relevant library versions: hot-shots 10.0.0**

[robaca]

I tested the same with Node 18.18.1 and 19.9.0, but didn't get that error

[svrakitin]

Managed to work around this issue like this:

import statsd from "hot-shots";
const { StatsD } = statsd;

[tlhunter]

FYI @khanayan123

[robaca]

Now the issue also occurs on Node 18.19.0.

I tried your workaround, but it doesn't work for me as-is in TypeScript code:

Referencing the type StatsD:

TS2749: StatsD refers to a value, but is being used as a type here. Did you mean typeof StatsD?

It also affects all kinds of modules, like mobx, express, ...

Testing with mobx 6.12.0:

This library is meant to be imported via import * as mobx from 'mobx' or named imports. There is also a default export, but not defined in types and some bundlers do not provide it. You can test it in a type="module" project via the repl:

$ node
> mobx = await import('mobx')
> Object.keys(mobx)
[
  '$mobx',
  'FlowCancellationError',
  'ObservableMap',
  'ObservableSet',
  'Reaction',
  ...
  'default',
  ...
]

dd-trace here is breaking both the named imports and also the access via mobx.

$ node --loader dd-trace/loader-hook.mjs
> mobx = await import('mobx')
> Object.keys(mobx)
[ 'default' ]

For now we have to use an older Node version until this is fixed.

[gingermusketeer]

I have run into this issue with @nestjs/common.

It appears that the DD loader is not exposing some of the exports from the module:

# With loader enabled
node --import ./register/datadog.mjs                                 
Welcome to Node.js v20.10.0.
Type ".help" for more information.
> (await import("@nestjs/common")).All
undefined
> 

# Without loader enabled
node                                
Welcome to Node.js v20.10.0.
Type ".help" for more information.
> (await import("@nestjs/common")).All
[Function (anonymous)]
>

register/datadog.mjs contains

import { register } from 'node:module'
import { pathToFileURL } from 'node:url'

register('dd-trace/loader-hook.mjs', pathToFileURL(import.meta.url))

[gingermusketeer]

This problem is solved for me by nodejs/import-in-the-middle#30. For now I am using patch-package to get it to work.