adding vertex llm

CHANGELOG.md

@@ -88,6 +88,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Added `AzureRealtimeBetaLLMService` to support Azure's OpeanAI Realtime API. Added
   foundational example `19a-azure-realtime-beta.py`.
 
+- Introduced `GoogleVertexAIService`, a new class for integrating with Vertex AI
+  Gemini models.
+
 ### Changed
 
 - Updated the default mode for `CartesiaTTSService` and

src/pipecat/services/google/google.py

@@ -71,6 +71,7 @@ try:
     import google.generativeai as gai
     from google import genai
     from google.api_core.client_options import ClientOptions
+    from google.auth.transport.requests import Request
     from google.cloud import speech_v2, texttospeech_v1
     from google.cloud.speech_v2.types import cloud_speech
     from google.genai import types
@@ -1333,6 +1334,78 @@ class GoogleLLMOpenAIBetaService(OpenAILLMService):
                     )
 
 
+class GoogleVertexAIService(OpenAILLMService):
+    """Implements inference with Google's AI models via Vertex AI while maintaining OpenAI API compatibility.
+    Reference:
+    https://cloud.google.com/vertex-ai/generative-ai/docs/multimodal/call-vertex-using-openai-library
+    """
+
+    class InputParams(OpenAILLMService.InputParams):
+        """Input parameters specific to Vertex AI."""
+
+        project_id: str
+        location: str
+
+    def __init__(
+        self,
+        *,
+        credentials: Optional[str] = None,
+        credentials_path: Optional[str] = None,
+        model: str = "google/gemini-1.5-flash",
+        params: InputParams = OpenAILLMService.InputParams(),
+        **kwargs,
+    ):
+        """Initializes the VertexLLMService.
+        Args:
+            credentials (Optional[str]): JSON string of service account credentials.
+            credentials_path (Optional[str]): Path to the service account JSON file.
+            model (str): Model identifier. Defaults to "google/gemini-1.5-flash".
+            params (InputParams): Vertex AI input parameters.
+            **kwargs: Additional arguments for OpenAILLMService.
+        """
+        base_url = self._get_base_url(params)
+        self._api_key = self._get_api_token(credentials, credentials_path)
+
+        super().__init__(api_key=self._api_key, base_url=base_url, model=model, **kwargs)
+
+    @staticmethod
+    def _get_base_url(params: InputParams) -> str:
+        """Constructs the base URL for Vertex AI API."""
+        return (
+            f"https://{params.location}-aiplatform.googleapis.com/v1/"
+            f"projects/{params.project_id}/locations/{params.location}/endpoints/openapi"
+        )
+
+    @staticmethod
+    def _get_api_token(credentials: Optional[str], credentials_path: Optional[str]) -> str:
+        """Retrieves an authentication token using Google service account credentials.
+        Args:
+            credentials (Optional[str]): JSON string of service account credentials.
+            credentials_path (Optional[str]): Path to the service account JSON file.
+        Returns:
+            str: OAuth token for API authentication.
+        """
+        creds: Optional[service_account.Credentials] = None
+
+        if credentials:
+            # Parse and load credentials from JSON string
+            creds = service_account.Credentials.from_service_account_info(
+                json.loads(credentials), scopes=["https://www.googleapis.com/auth/cloud-platform"]
+            )
+        elif credentials_path:
+            # Load credentials from JSON file
+            creds = service_account.Credentials.from_service_account_file(
+                credentials_path, scopes=["https://www.googleapis.com/auth/cloud-platform"]
+            )
+
+        if not creds:
+            raise ValueError("No valid credentials provided.")
+
+        creds.refresh(Request())  # Ensure token is up-to-date, lifetime is 1 hour.
+
+        return creds.token
+
+
 class GoogleTTSService(TTSService):
     class InputParams(BaseModel):
         pitch: Optional[str] = None