[Bug] AppCheck fails in debug environment with Firebase 11.9.0 about firebase-unity-sdk

[google-oss-bot]

I couldn't figure out how to label this issue, so I've labeled it for a human to triage. Hang tight.

[argzdev]

Hey @Nyankoo, thanks for reaching out. I was able to reproduce the same behavior. Oddly enough, when I tested this on a native android app, this is working alright. I'm guessing there might be a miscommunication between the different Firebase products with AppCheck in Unity. I'll go ahead and inform our engineers. Thanks!

[Nyankoo]

@argzdev Glad it could also be reproduced on your end and I hope for a fix soon, as it makes testing in the Unity Editor quite hard.

[argzdev]

Hi @Nyankoo, so while I was waiting for engineering feedback. I noticed that after testing today, the issue went away. Upon further investigation, it looks like the issue was due to multiple reasons:

1. Delayed "reaction" of the debug token from the App Check services, which was interpreted by the system as unverified requests.
2. AppCheck does not work when testing it in the default Unity IDE. I noticed a different behavior where on the Unity IDE Firestore fails to write a document, and on the Android Emulator the Firestore write was able to go through. In this case, you'd have to Build and Run the app on an Android Emulator.
3. Lastly, I noticed my Firestore rules was restricting the writing of the document. You could try isolating the issue by first testing without AppCheck and see if everything is working correctly. Perhaps this will isolate the issue.

Also I've tested using our quickstart for Firestore and added AppCheck:

protected virtual void Start()
    {

      FirebaseApp.CheckAndFixDependenciesAsync().ContinueWithOnMainThread(task =>
      {
        dependencyStatus = task.Result;
        if (dependencyStatus == DependencyStatus.Available)
        {
          InitializeFirebase();
          InitializeAppCheck();
        }
        else
        {
          Debug.LogError(
            "Could not resolve all Firebase dependencies: " + dependencyStatus);
        }
      });
    }

Let me know if this helps!

[Nyankoo]

@argzdev Can you please elaborate on reason 2? App Check was working previously in the Unity Editor with the instructions found here:
https://firebase.google.com/docs/app-check/unity/debug-provider

It also explicitly states:

After you have registered your app for App Check, your app normally won't run on desktop platforms, in an emulator, or from a continuous integration (CI) environment, since those environments don't qualify as valid devices. If you want to run your app in such an environment during development and testing, you can create a debug build of your app that uses the App Check debug provider instead of a real attestation provider.

[argzdev]

Reason #2 was the behavior I encountered when testing for both Unity and in Android Emulator. I believe you're right, it should be working even on desktop platforms as mentioned in the documentations. So I'm guessing the main culprit is that the Debug token doesn't work on the desktop platform, but works on the Android Emulator. Let me add that to my escalation for our engineers.

By the way, you mentioned that it was previously working. Could you specify which version were you using before encountering this behavior?

[Nyankoo]

I do believe that it was working with 11.8.1, but this could also be a mix-up with recent changes of enforcement we did on the Firebase dashboard.

[argzdev]

We'll keep that in mind while investigating, thank you for the additional information!

[a-maurice]

Hi @Nyankoo

I tried it on my end, and it does work on my end without issue. I can get that error message by not setting up the DebugAppCheckProviderFactory correctly, so that is my best guess on what could be going wrong. It is important to note that setting the factory needs to be done before any other Firebase call.

Somethings to try, you could enable debug logging to see if anything stands out in the log about what AppCheck provider is being used with the calls.

Firebase.FirebaseApp.LogLevel = Firebase.LogLevel.Debug;

[Nyankoo]

@a-maurice I just tried it too, and it's still not working for me. Which Unity version did you try it with?

Here is my code:

DebugAppCheckProviderFactory.Instance.SetDebugToken("MYDEBUGTOKEN"); //This is set to the correct debug token
FirebaseAppCheck.SetAppCheckProviderFactory(DebugAppCheckProviderFactory.Instance);

var dependencyStatus = await FirebaseApp.CheckAndFixDependenciesAsync();
if(dependencyStatus != DependencyStatus.Available)
{
      return;
}

//do Firebase calls after this

[a-maurice]

I tried it with 2021.3.38f1, and had previously done tests with 2021.3.13f1, so I doubt that would be part of the reason why. And yeah, that code looks like the correct order for things.

I do see that the Firestore SDK updated some of their dependencies in the iOS SDK, which is partially used by the desktop implementation, though looking over those changes nothing seems like it would be related to App Check issues. I assume it is all the calls to Firestore having issues, and not just a specific one? Are you using any of the other Firebase products that use App Check (Storage, Realtime Database, Functions), to see if those are working for you?

[Nyankoo]

@a-maurice Only using Firestore that has App Check "enforced".

The additional debug message I'm getting is: "Would set key-value if running on a physical device: KEY-VALUE"