fix: fix bigquery credentials and bigquery tool to make it compatible with python 3.9 and make the credential serializable in session

PiperOrigin-RevId: 763332829

src/google/adk/tools/bigquery/bigquery_credentials.py

@@ -12,6 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from __future__ import annotations
+
 from typing import List
 from typing import Optional
 
@@ -33,15 +35,31 @@ from ..tool_context import ToolContext
 BIGQUERY_TOKEN_CACHE_KEY = "bigquery_token_cache"
 
 
-class BigQueryCredentials(BaseModel):
+class BigQueryCredentialsConfig(BaseModel):
   """Configuration for Google API tools. (Experimental)"""
 
   # Configure the model to allow arbitrary types like Credentials
   model_config = {"arbitrary_types_allowed": True}
 
   credentials: Optional[Credentials] = None
-  """the existing oauth credentials to use. If set will override client ID,
-  client secret, and scopes."""
+  """the existing oauth credentials to use. If set,this credential will be used
+  for every end user, end users don't need to be involved in the oauthflow. This
+  field is mutually exclusive with client_id, client_secret and scopes.
+  Don't set this field unless you are sure this credential has the permission to
+  access every end user's data.
+
+  Example usage: when the agent is deployed in Google Cloud environment and
+  the service account (used as application default credentials) has access to
+  all the required BigQuery resource. Setting this credential to allow user to
+  access the BigQuery resource without end users going through oauth flow.
+
+  To get application default credential: `google.auth.default(...)`. See more
+  details in https://cloud.google.com/docs/authentication/application-default-credentials.
+
+  When the deployed environment cannot provide a pre-existing credential,
+  consider setting below client_id, client_secret and scope for end users to go
+  through oauth flow, so that agent can access the user data.
+  """
   client_id: Optional[str] = None
   """the oauth client ID to use."""
   client_secret: Optional[str] = None
@@ -51,12 +69,20 @@ class BigQueryCredentials(BaseModel):
   """
 
   @model_validator(mode="after")
-  def __post_init__(self) -> "BigQueryCredentials":
+  def __post_init__(self) -> BigQueryCredentialsConfig:
     """Validate that either credentials or client ID/secret are provided."""
     if not self.credentials and (not self.client_id or not self.client_secret):
       raise ValueError(
           "Must provide either credentials or client_id abd client_secret pair."
       )
+    if self.credentials and (
+        self.client_id or self.client_secret or self.scopes
+    ):
+      raise ValueError(
+          "Cannot provide both existing credentials and"
+          " client_id/client_secret/scopes."
+      )
+
     if self.credentials:
       self.client_id = self.credentials.client_id
       self.client_secret = self.credentials.client_secret
@@ -71,14 +97,14 @@ class BigQueryCredentialsManager:
   the same authenticated session without duplicating OAuth logic.
   """
 
-  def __init__(self, credentials: BigQueryCredentials):
+  def __init__(self, credentials_config: BigQueryCredentialsConfig):
     """Initialize the credential manager.
 
     Args:
-        credential_config: Configuration containing OAuth details or existing
-          credentials
+        credentials_config: Credentials containing client id and client secrete
+        or default credentials
     """
-    self.credentials = credentials
+    self.credentials_config = credentials_config
 
   async def get_valid_credentials(
       self, tool_context: ToolContext
@@ -87,18 +113,23 @@ class BigQueryCredentialsManager:
 
     Args:
         tool_context: The tool context for OAuth flow and state management
-        required_scopes: Set of OAuth scopes required by the calling tool
 
     Returns:
         Valid Credentials object, or None if OAuth flow is needed
     """
-    # First, try to get cached credentials from the instance
-    creds = self.credentials.credentials
+    # First, try to get credentials from the tool context
+    creds_json = tool_context.state.get(BIGQUERY_TOKEN_CACHE_KEY, None)
+    creds = (
+        Credentials.from_authorized_user_info(
+            creds_json, self.credentials_config.scopes
+        )
+        if creds_json
+        else None
+    )
 
-    # If credentails are empty
+    # If credentails are empty use the default credential
     if not creds:
-      creds = tool_context.get(BIGQUERY_TOKEN_CACHE_KEY, None)
-      self.credentials.credentials = creds
+      creds = self.credentials_config.credentials
 
     # Check if we have valid credentials
     if creds and creds.valid:
@@ -110,7 +141,7 @@ class BigQueryCredentialsManager:
         creds.refresh(Request())
         if creds.valid:
           # Cache the refreshed credentials
-          self.credentials.credentials = creds
+          tool_context.state[BIGQUERY_TOKEN_CACHE_KEY] = creds.to_json()
           return creds
       except RefreshError:
         # Refresh failed, need to re-authenticate
@@ -140,7 +171,7 @@ class BigQueryCredentialsManager:
                 tokenUrl="https://oauth2.googleapis.com/token",
                 scopes={
                     scope: f"Access to {scope}"
-                    for scope in self.credentials.scopes
+                    for scope in self.credentials_config.scopes
                 },
             )
         )
@@ -149,8 +180,8 @@ class BigQueryCredentialsManager:
     auth_credential = AuthCredential(
         auth_type=AuthCredentialTypes.OAUTH2,
         oauth2=OAuth2Auth(
-            client_id=self.credentials.client_id,
-            client_secret=self.credentials.client_secret,
+            client_id=self.credentials_config.client_id,
+            client_secret=self.credentials_config.client_secret,
         ),
     )
 
@@ -165,14 +196,14 @@ class BigQueryCredentialsManager:
           token=auth_response.oauth2.access_token,
           refresh_token=auth_response.oauth2.refresh_token,
           token_uri=auth_scheme.flows.authorizationCode.tokenUrl,
-          client_id=self.credentials.client_id,
-          client_secret=self.credentials.client_secret,
-          scopes=list(self.credentials.scopes),
+          client_id=self.credentials_config.client_id,
+          client_secret=self.credentials_config.client_secret,
+          scopes=list(self.credentials_config.scopes),
       )
 
       # Cache the new credentials
-      self.credentials.credentials = creds
-      tool_context.state[BIGQUERY_TOKEN_CACHE_KEY] = creds
+      tool_context.state[BIGQUERY_TOKEN_CACHE_KEY] = creds.to_json()
+
       return creds
     else:
       # Request OAuth flow

src/google/adk/tools/bigquery/bigquery_tool.py

@@ -17,13 +17,13 @@ import inspect
 from typing import Any
 from typing import Callable
 from typing import Optional
-from typing import override
 
 from google.oauth2.credentials import Credentials
+from typing_extensions import override
 
 from ..function_tool import FunctionTool
 from ..tool_context import ToolContext
-from .bigquery_credentials import BigQueryCredentials
+from .bigquery_credentials import BigQueryCredentialsConfig
 from .bigquery_credentials import BigQueryCredentialsManager
 
 
@@ -41,7 +41,7 @@ class BigQueryTool(FunctionTool):
   def __init__(
       self,
       func: Callable[..., Any],
-      credentials: Optional[BigQueryCredentials] = None,
+      credentials: Optional[BigQueryCredentialsConfig] = None,
   ):
     """Initialize the Google API tool.