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​
Overview

The MABQ BigQuery Agent backend is built with FastAPI and integrates the Google ADK (Agent Development Kit) to provide a conversational interface for BigQuery data analysis.

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Application Configuration

The FastAPI app is configured with strict CORS policies and security middleware. 
app = FastAPI(title="Transelec MABQ Agent")

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CORS Middleware

The application enforces strict CORS to allow only authorized frontend origins: 
FRONTEND_URL = os.environ.get(
    "FRONTEND_URL", 
    "https://mabq-frontend-1093163678323.us-east4.run.app"
)

app.add_middleware(
    CORSMiddleware,
    allow_origins=[FRONTEND_URL], 
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)
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allow_origins
list[str]
Single frontend URL from environment variable FRONTEND_URL
​
allow_credentials
bool
default:"true"
Enables cookie and authorization header support
​
allow_methods
list[str]
default:"['*']"
All HTTP methods allowed
​
allow_headers
list[str]
default:"['*']"
All headers allowed for authenticated requests

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Endpoints

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ADK Agent Endpoint

The main conversational agent endpoint is registered at the root path by the ADK framework. 
from ag_ui_adk import ADKAgent, add_adk_fastapi_endpoint

adk_wrapper = ADKAgent(
    adk_agent=agente_backend, 
    app_name="transelec-mabq", 
    user_id="verified-user",
    use_in_memory_services=True
)

add_adk_fastapi_endpoint(app, adk_wrapper, path="/")
​
path
string
default:"/"
Root path where the ADK agent is mounted
​
use_in_memory_services
bool
default:"true"
Uses in-memory session storage for conversation state

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Response Format

The ADK endpoint returns agent responses in a streaming or JSON format depending on the client configuration.
​
message
string
Agent’s response to the user query
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sql
string
Generated SQL query (when applicable)
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results
array
Query results from BigQuery (when executed)

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Documentation Endpoints

FastAPI automatically generates interactive API documentation:
  • Swagger UI: /docs
  • ReDoc: /redoc
  • OpenAPI Schema: /openapi.json
These endpoints are exempt from authentication for development purposes.

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Security Middleware

All endpoints (except /docs, /openapi.json, and GET requests to /) are protected by the authentication middleware. See Authentication for details.
The middleware exempts OPTIONS requests and specific paths for development and root access (see main.py:34-37).

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Running the Server

The application runs with Uvicorn on port 8000: 
if __name__ == "__main__":
    uvicorn.run(app, host="0.0.0.0", port=8000)
​
host
string
default:"0.0.0.0"
Binds to all network interfaces for container deployment
​
port
int
default:"8000"
HTTP port for the FastAPI application

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Environment Variables

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FRONTEND_URL
string
required
Authorized frontend origin for CORS
​
AZURE_TENANT_ID
string
required
Azure AD tenant ID for JWT validation
​
AZURE_CLIENT_ID
string
required
Azure AD application client ID (audience)

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Example Deployment

apiVersion: v1
kind: Service
metadata:
  name: mabq-backend
spec:
  ports:
  - port: 8000
    targetPort: 8000
  selector:
    app: mabq-backend

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