Add Cors to callable function

I wrote a callable function to invite new users for my app:

exports.UserInvitation = functions.https.onCall((data, context) => {
  const email = data.email
  const password = passwordGenerator.generate({
    length: 12,
    numbers: true
  })
  console.log('Inviting user:', email)
  const mailOptions = {
    from: '',
    to: email,
    subject: ``,
    html: utils.formatEmail(`
     Hello, you've been invited to use my app.
    `)
  }

  return new Promise((resolve, reject) => {
    admin.auth().createUser({
      email: email,
      emailVerified: false,
      password: password
    }).then((user) => {
      console.log(`Created user with uid ${user.uid}`)
      transporter.sendMail(mailOptions).then(() => {
        console.log(`Email sent to ${email}`)
        resolve()
      })
    }).catch((err) => {
      console.error(err.code)
      reject(new functions.https.HttpsError(err.code, err.message))
    })
  })
})

I call it like this in my app:

functions.httpsCallable('UserInvitation')({ email: this.input.value })

But I’m getting “No Access Control Allow Origin” error when trying to call it from client. How can I fix this if I don’t have access to req/res objects inside onCall, to enable cors?

[marimano]

I recently faced the CORS error only for newly created functions. After hours of desperate search I found that newly created functions don’t have Cloud Functions Invoker at https://console.cloud.google.com/functions while the old ones have allUsers:

Here firebase mentions that starting from Jan 15, 2020 no allUsers is set anymore https://cloud.google.com/functions/docs/securing/managing-access-iam

[8tomo8]

@tricaricom @nicholmikey The CORS error in console with callable functions only indicates there is an error in the cloud function. Check the logs inside the Firebase console and you’ll see the actual error. CORS is not applicable for callable functions even when running on localhost