"ERR_REQUIRE_ESM" when using native modules about heroku-nodejs-plugin

[danielleadams]

Hi @luax, this is on my list, but unfortunately haven't gotten around to it yet. For what it's worth, I would like to get this fixed as soon as possible since I think this is important to support, but since Node.js Language Metrics is a beta feature, it becomes a little harder to prioritize.

Nonetheless, I will keep this issue updated with my progress.

[danielleadams]

Hi @luax - this is the right place for this bug. I will investigate this and report back. It has to do with the plugin's use of require when ES Modules have been enabled. The plugin will need to do ES module-style imports when it's enabled, so I need to figure out what that looks like.

[luax]

Thanks @danielleadams! I also created a support ticket.

Here is a reproducible example:

• package.json

  {
    "name": "heroku-test",
    "version": "1.0.0",
    "main": "index.js",
    "license": "MIT",
    "type": "module",
    "engines": {
      "node": "14.x"
    },
    "dependencies": {
      "express": "4.17.1"
    }
  }
  

• index.js

  import express from 'express';
  
  const app = express()
  const port = process.env.PORT || 3000
  
  app.get('/', (req, res) => res.send('Hello World!'))
  
  app.listen(port, () => console.log(`Example app listening at http://localhost:${port}`))
  

[luax]

Sorry but are there any news on when this might be solved @danielleadams?

My current workaround is booting with:

web: echo { \"type\": \"commonjs\" } > /app/.heroku/heroku-nodejs-plugin/package.json && node index.js

Or not use native modules as it seems risky to add things to /app/.heroku on the fly.

Thanks!

[imargulyan]

I face the same problem on a Hobby Dyno at Heroku. It is definitely an issue with heroku-nodejs-plugin since I dont face it on a Free Dyno which doesnt have metrics plugin but running the same code. Node v14.5

[lblo]

Hi,
I'm also having the same issue after migrating my Node project to "type": "module" and killing all the require in my project...
I'll try luax's solution.

[ahmadyousef1125]

Can confirm also.
When turning on this switch:

and setting "type": "module" in the package.json, then the app crashes with the mentioned error.

[danielleadams]

The fix will go out with the next release.