Add prototype for Firebase Vertex AI

[andrewheard]

Do not merge. This is a prototype that uses Vertex AI with the Google Generative AI SDK.

Usage:

import FirebaseCore
import FirebaseVertexAI
...
FirebaseApp.configure()
let model = VertexAI.vertexAI().generativeModel(modelName: "gemini-1.0-pro")
    
Task {
  let responses = model.generateContentStream("Why is the sky blue?")
  for try await response in responses {
    if let text = response.text {
      print(text)
    } else {
      print("No text in candidate.")
    }
  }
}

#no-changelog

[peterfriese]

Just a few minor remarks.

I love that most of the code for the samples can stay the same!

[peterfriese]

This might no longer be applicable, and the message we issue in line 155 might mislead people.

[andrewheard]

Good call. I updated the message to refer to the GoogleService-Info.plist instead since an invalidAPIKey error in this SDK would be because of Firebase mis-configuration (or revocation of the Firebase app's API key).

I would probably leave this error case out entirely if the prototype weren't built on top of the existing generative-ai-swift SDK.

[peterfriese]

I wonder if this is still going to be an issue. Even when providing europe-west1, the model happily answers.

[andrewheard]

I removed this case from the switch statement since it'll never be thrown with Vertex AI. Gemini is available on Vertex AI in these Cloud regions but can be called from anywhere (e.g., I could specify europe-west1 but latency from North America will be higher).

[peterfriese]

Force unwrap makes me feel uneasy...

[andrewheard]

Added a fatalError instead of a force-unwrap. The following error message will also be logged in this scenario:

firebase-ios-sdk/FirebaseCore/Sources/FIRApp.m

Lines 238 to 245 in 86ae5de

	FIRLogError(kFIRLoggerCore, @"I-COR000003",
	@"The default Firebase app has not yet been "
	@"configured. Add `FirebaseApp.configure()` to your "
	@"application initialization. This can be done in "
	@"in the App Delegate's application(_:didFinishLaunchingWithOptions:)` "
	@"(or the `@main` struct's initializer in SwiftUI). "
	@"Read more: https://goo.gl/ctyzm8.");
	return nil;

[peterfriese]

Shouldn't this rather be modelResourcePath? In line 93, we return a path (or at least a path fragment).

[andrewheard]

I chose this function name because it's a model resource name in resource-oriented design (see https://google.aip.dev/122).

Note: The field in the REST API is called model instead of name.

[peterfriese]

Force unwrap makes me feel uneasy...

[andrewheard]

Added a fatalError instead of the force unwrap.

[peterfriese]

In case of a misconfiguration like a missing project ID, shouldn't we at least issue a warning on the log?

[andrewheard]

I changed this to a fatalError as well. If projectID is nil then something is wrong with the Firebase app configuration.

[peterfriese]

There doesn't seem to be a check for the location.

[andrewheard]

Since location isn't an optional parameter I added a check for "". Beyond that I'll leave it up to the backend to return a 404 error if an invalid location is specified.

[peterfriese]

Remove the comma before if

Adds an App Check token to the provided request if App Check is included in the app.

Also, do we add the token even if App Check is just included in the app? Or does it have to be enabled for us to send the token?

[andrewheard]

It's good to send the App Check token, if it's included in the app, even if it's not enabled for the Firebase project / app. If it's not enabled at all then it'll just be ignored by the backend. If App Check is enabled but unenforced then developers will be able to see how many requests would be blocked if/when they enforce App Check.

[paulb777]

Closing. VertexAI support is now in main