Firebase-tools: Documentation: debug() function for Firestore emulator

[gaeldestrem]

According your changelog, you have introduced a debug(...) function for the firestore emulator in the v6.14.0 but we couldn't find any documentation for it.

Can you help us on how to use it?

[ryanpbrewster]

Ah, very perceptive :smile:. Keeping in mind that this feature is not yet well-documented:

When running the Firestore emulator, you can use the debug(...) function in your security rules to cause the emulator to print out the value passed into the function. So for example:

service cloud.firestore {
  match /databases/{db}/documents {
    match /{doc=**} {
      allow read, write: if debug(request.auth) != null;
    }
  }
}

will allow any request from an authenticated user, and will additionally print out the value of request.auth (to stdout in whatever terminal you're running the emulator from).

[mpppk]

In firestore emulator v1.10.2, the emulator seems to only output the debug log to the firestore-debug.log, not stdout.

[ryanpbrewster]

In this case I'm assuming you're running the Firestore emulator via

firebase emulators:start --only firestore

or something like it. This "wrapper" command starts up the Firestore emulator and routes its stdout into the local firestore-debug.log file.

[akauppi]

I'd find the debug() useful, especially if it prints to stdout.

[yuchenshi]

Somehow we forgot to close this issue, but debug() was supported since the OP, and we've documented it as well at https://firebase.google.com/docs/reference/rules/rules.debug . Cheers!