Emulator does not invoke function when making a HTTP pre-flight OPTIONS request (firebase-tools v10)

[jowo-io]

Loving the features the firebase team is releasing - so cool being able to run my entire firebase stack locally through the emulator.

I was pulling my hair out today attempting to debug a CORS issues. When invoking a function I was getting CORS issues and eventually tracked the root of the issue down to the pre-flight request not returning the access-control-allow-credentials header.

I realised that the function was no longer being invoked when requested with the OPTIONS http status when running the firebase-tool@v10 emulator. I'll attach a few screenshots below of requests made with postman

v9

"firebase-tools": "^9.23.3",

Foobar

When pinging the URL http://localhost:7000/foobar

The emulator returns a generic set of headers

Function

When pinging the URL http://localhost:7000/<my-project>/us-central1/auth-login (the actual emulator function URL)

The emulator did invoke my function, and ran my code, then returns a custom header that I've configured it to return.

v10

"firebase-tools": "^10.2.2",

Foobar

When pinging the URL http://localhost:7000/foobar

The emulator returns a generic set of headers

Function

When pinging the URL http://localhost:7000/<my-project>/us-central1/auth-login (the actual emulator function URL)

The emulator does not invoke my function, instead it returns a generic set of headers

[jowo-io]

just realised I may have posted this in the wrong place?

[joehan]

@jowo-io Thanks for reporting this. I think I broke this recently while adding support for a new emulator UI feature. I'll do some testing this afternoon and hopefully have a fix out soon.