Why am I only getting Mailgun.js error in Cloud Run?

Question

I'm trying to send an email using Mailgun's npm client - Mailgun.js.

When sending in development mode, everything works correctly. But when I upload the Node server to Cloud Run, something breaks.

Here is the code in the sendEmail helper file:

import formData from 'form-data';
import Mailgun from 'mailgun.js';

const sendEmail = async ({ to, subject, text, attachment, scheduledDate }) => {
  const mailgun = new Mailgun(formData);
  const mg = mailgun.client({
    username: 'api',
    key: process.env.MAILGUN_KEY,
    url: 'https://api.eu.mailgun.net'
  });

  const data = {
    from: `<[email protected]>`,
    to,
    subject,
    text
  };

  if (attachment) {
    data.attachment = attachment;
  }

  if (scheduledDate) {
    data['o:deliverytime'] = new Date(scheduledDate).toUTCString();
  }
  
  try {
    const result = await mg.messages.create(process.env.MAILGUN_DOMAIN, data);

    if (result.status && result.status !== 200) {
      throw ({ code: result.status, message: result.message });
    }

    return true;
  } catch(err) {
    console.log(err);
    return { error: err };
  }
};

export default sendEmail;

And then in another file:

import { Router } from 'express';
import generateInvoicePDF from '../helpers/generateInvoicePDF.js';
import sendEmail from '../helpers/sendEmail.js';

const router = Router();

router.post('/email', async (req, res, next) => {
  try {
    const file = await generateInvoicePDF(invoice);

    if (file?.error) {
      throw ({ code: pdf.error.code, message: pdf.error.message });
    }

    const email = await sendEmail({
      to: '[email protected]',
      subject: 'Invoice',
      text: 'Test',
      attachment: { filename: 'Invoice', data: file }
    });
    
    if (email?.error) {
      throw ({ code: email.error.code, message: email.error.message });
    }

    res.status(200).json({ success: true });
  } catch(err) {
    next(err);
  }
});

export default router;

The error I get when in production mode in Cloud Run's logs is:

TypeError: fetch failed 
at Object.processResponse (node:internal/deps/undici/undici:5575:34) 
at node:internal/deps/undici/undici:5901:42 
at node:internal/process/task_queues:140:7 
at AsyncResource.runInAsyncScope (node:async_hooks:202:9) 
at AsyncResource.runMicrotask (node:internal/process/task_queues:137:8) {
  cause: TypeError: object2 is not iterable 
  at action (node:internal/deps/undici/undici:1661:39) 
  at action.next (<anonymous>)
  at Object.pull (node:internal/deps/undici/undici:1709:52)
  at ensureIsPromise (node:internal/webstreams/util:172:19)
  at readableStreamDefaultControllerCallPullIfNeeded (node:internal/webstreams/readablestream:1884:5)
  at node:internal/webstreams/readablestream:1974:7
}

Why the hell does it work in development mode on my local machine, but not when uploaded to Cloud Run?

Answer 1

For anyone struggling with something similar - I eventually figured out the problem.

On my local machine, where everything was working as expected, I'm using Node v16.15.0, whereas in the Dockerfile, I had specified

FROM node:latest

and therefore Cloud Run was using a newer version, which led to the problems...

I've now deployed using version 16.15.0 and everything works fine