Inconsistent date format of `createdAt` and `lastSignedInAt` at UserMetadata between firebase-admin and function-trigger data

[adrianjost]

My environment

• Operating System version: irrelevant
• Firebase SDK version: check below
• Firebase Product: auth, functions
• Node.js version: 14.18.1
• NPM version: 6.14.15

"firebase": "^9.2.0",
"firebase-admin": "^9.12.0",
"firebase-functions": "^3.15.7",

The problem

The UserMetadata class defines the type of creationTime and lastSignInTime as a UTC string. However, the actual date format returned by the admin SDK differs from the format returned by the cloud function onCreate date format, even though both claim to implement the same interface.

The Admin SDK seems to use the RFC7231 format (Thu, 28 Oct 2021 08:53:26 GMT), where as the Firebase Functions use the ISO format (2016-12-15T19:37:37.059Z).

The Functions Specs mention that they use the same UserRecord as the Firebase Admin SDK
https://firebase.google.com/docs/reference/functions/providers_auth.userbuilder#user:-userrecord
=> https://firebase.google.com/docs/reference/functions/providers_auth#userrecord

The UserRecord passed to Cloud Functions is the same UserRecord that is returned by the Firebase Admin SDK.

and the Admin SDK defines the date as an UTC string: https://github.com/firebase/firebase-admin-node/blob/master/src/auth/user-record.ts#L300

This is also reflected in the test suites:
Admin SDK: https://github.com/firebase/firebase-admin-node/blob/master/test/integration/auth.spec.ts#L240
Firebase Functions: https://github.com/firebase/firebase-functions/blob/master/spec/v1/providers/auth.spec.ts#L179

I am kindly requesting this to be unified, since it is very confusing to use. Preferably with the ISO format.

Relevant Code:

Admin SDK:

const user = await admin.auth().getUser(uid)
console.log(user.metadata.creationTime)
// Thu, 01 Jan 1970 00:00:00 UTC

Firebase Authentication trigger:

exports.test = functions.auth.user().onCreate((user) => {
console.log(user.metadata.creationTime)})
// 2017-02-02T23:06:26.124Z

[hiranya911]

@bojeil-google WDYT?

firebase-functions implement our UserMetadata interface, but doesn't use the same timestamp format that we use in the Admin SDK. Where should we fix this?

[bojeil-google]

Hey @hiranya911, I wasn't aware of this. We should reach out to the cloud functions folks (I don't have visibility to their side of things). They receive the data from us but I am not sure how they reformat (or whether they use it as is).

[hiranya911]

They seem to be using it as is. @lahirumaramba @inlined can you take a look?

[lahirumaramba]

The Admin SDK exposes timestamps in UTC date strings and this is consistent across the existing Admin APIs. Taking a quick glance at the functions code it looks like firebase-functions usually expose timestamps in ISO format. I think it might help if both SDKs align on the same date formatting.

@inlined @taeold do you know where we handle the date strings in functions code?

[inlined]

Looks like this is the LOC you're looking for. Firebase Auth is sending a google.protobuf.Timestamp down the wire, which is encoded as an ISO string in JSON. We simply expose this directly. I agree this is a bug, and we can add some ugly date logic here to fix.

The only gotcha is that I'm not sure if this fix should be held back for a major revision since it could be a pretty breaking change.

[inlined]

We've decided to close this issue. Firebase Functions has the ideal behavior and we'll queue the other SDKs to match this behavior on their next breaking changes.