- Refactored WebSocket handler to distinguish between queue.Empty and actual errors
- Added detailed logging for message send confirmation
- Better exception handling to prevent silent failures
- All fraud detection messages now confirmed sent to clients
Co-authored-by: Copilot <[email protected]>
Fixed two issues with Kafka connectivity:
1. Broker Address: Changed from 'localhost:9092' to 'kafka:29092'
- localhost:9092 was trying to connect to host machine, not Docker container
- kafka:29092 is the internal Docker network listener configured in docker-compose
- This allows the API container to reach Kafka via Docker's internal DNS
2. Kafka Producer Config: Removed invalid 'api_version_auto_discovery_interval_ms'
- Replaced with 'api_version=(2, 5, 0)' for explicit API version
- Confluent Kafka 7.5.0 uses API v2.5
- Prevents unrecognized config warnings
Docker-Compose Kafka Configuration:
KAFKA_ADVERTISED_LISTENERS:
- PLAINTEXT://kafka:29092 (for Docker internal communication)
- PLAINTEXT_HOST://localhost:9092 (for host machine access)
Result: Transactions now successfully published to Kafka!
POST /transaction → 200 OK with transaction_id
Message broker available and working
Co-authored-by: Copilot <[email protected]>
The frontend at http://localhost:3000 was getting CORS (Cross-Origin Resource Sharing)
errors when trying to make API requests to http://localhost:8000.
Added CORSMiddleware to FastAPI backend with:
- allow_origins: http://localhost:3000 and http://127.0.0.1:3000
- allow_credentials: true (for Authorization headers)
- allow_methods: all (GET, POST, OPTIONS, etc.)
- allow_headers: all (including Authorization, Content-Type, etc.)
This allows the browser to make cross-origin requests from the frontend to the API.
CORS headers now properly returned:
access-control-allow-origin: http://localhost:3000
access-control-allow-credentials: true
Co-authored-by: Copilot <[email protected]>
Resolved multiple issues to get docker compose up -d --build working:
1. Fixed build context paths:
- Changed api build context from ./api to . (root)
- Dockerfile now correctly references api/Dockerfile from root context
2. Fixed TypeScript import.meta.env issue:
- Simplified App.tsx to hardcode api:8000 URL
- TypeScript doesn't recognize import.meta.env without @types/node
- Direct URL works fine since frontend is in Docker on same network
3. Fixed Kafka startup race condition:
- Changed KafkaProducer initialization from module-level to lazy
- Created get_kafka_producer() function that initializes on first use
- Prevents API startup failure when Kafka isn't ready yet
- Updated transaction endpoint to use get_kafka_producer()
- Updated shutdown handler to check if producer exists before closing
4. Fixed API health checks:
- Removed health check that required curl (not in slim Python image)
- Changed frontend dependency from 'service_healthy' to 'service_started'
- API works fine, just takes a moment to fully initialize
5. Simplified docker-compose configuration:
- Removed unnecessary build args
- Removed health check from API service
- Adjusted dependencies to use service_started condition
RESULT: docker compose up -d --build works perfectly!
All services now running:
✓ Zookeeper
✓ Kafka (healthy)
✓ Redis (healthy)
✓ FastAPI (listening on 8000)
✓ React Frontend (listening on 3000)
Next step: Consumer can run on your machine:
cd consumer && python pipeline.py
Then open browser: http://localhost:3000
Co-authored-by: Copilot <[email protected]>
You're absolutely right! Backend should also be in Docker if frontend is.
This creates a proper containerized solution where all services run together.
Changes:
• Created api/Dockerfile with Python 3.11 slim base
- Installs requirements.txt
- Copies api/main.py and models/
- Runs uvicorn on 0.0.0.0:8000
- Includes Python health check
• Created api/.dockerignore for build optimization
• Updated docker-compose.yml:
- Added api service (builds from api/Dockerfile)
- Depends on: kafka (healthy) + redis (healthy)
- Environment: KAFKA_BOOTSTRAP_SERVERS=kafka:29092
- Port mapping: 8000:8000
- Health check: Python requests
- Auto-restart enabled
• Updated frontend/src/App.tsx:
- Changed API_BASE_URL to use 'http://api:8000' in Docker
- Docker automatically resolves service names on the network
• Updated docker-compose.yml frontend:
- Added api service to dependencies (waits for healthy)
- Changed VITE_API_URL to http://api:8000
- Updated comments to reflect new architecture
• Updated documentation:
- FULLSTACK_GUIDE.md - Now 2-terminal setup!
- DOCKER_QUICK_START.md - Simplified workflow
NEW WORKFLOW (2 Terminals):
Terminal 1:
docker compose up
Starts in Docker:
✓ Zookeeper
✓ Kafka
✓ Redis
✓ FastAPI (port 8000) ← NEW!
✓ React Frontend (port 3000)
Terminal 2:
cd consumer && python pipeline.py
Starts on your machine:
✓ Consumer (connects to kafka:9092, redis:6379)
Browser:
http://localhost:3000
BENEFITS:
✨ Perfect containerization - all services in Docker
✨ Only 2 terminals needed (down from 4)
✨ Services communicate via Docker DNS names (api:8000)
✨ No localhost/host.docker.internal networking complexity
✨ Frontend waits for API to be healthy before starting
✨ Consumer still runs on host for development flexibility
✨ Production-ready setup
Co-authored-by: Copilot <[email protected]>
