API Reference

API Reference

It documents the public application entry points and the internal modules used by the Serverless Runtime.

Main Application (app/main.py)

The FastAPI application is defined in app/main.py and configures logging, Prometheus metrics, and RabbitMQ consumer startup (when run directly).

Routes

• GET /: Returns a string with the main route hint.
• POST /control/stop-consuming: Gracefully stops the RabbitMQ consumer if running.
• Router prefix /v1/faas: Additional FaaS endpoints provided by faas_router in app/api/v1/faas.py.

Runtime & Metrics

• Initializes Prometheus metrics and starts a metrics HTTP server on port 9100.
• Integrates Uvicorn logging with the custom CognitLogger (app/modules/_logger.py).
• When executed directly (python app/main.py):
  • Starts a RabbitMQClient (app/modules/_rabbitmq_client.py) in a background thread.
  • Runs Uvicorn with host/port arguments.

CLI Arguments

• --host (default 127.0.0.1): API host address.
• --flavour (required): RabbitMQ queue name. Must match an existing FLAVOUR within the COGNIT framework.
• --broker (required): RabbitMQ broker address.
• --port (default 8000): API server port.

Core Modules

Internal modules are located under app/modules/ and implement logging, execution, parsing, storage, and messaging.

• _logger.py: CognitLogger providing structured logging used across the runtime and integrated with Uvicorn.
• _executor.py: Base execution logic for running offloaded functions (supports Python and C paths).
• _pyexec.py: Extends the base executor with Python-specific execution behaviour.
• _faas_parser.py: Serialization/deserialization of offloaded functions and returned results.
• _minio_client.py: Client utilities for CRUD operations against MinIO.
• _rabbitmq_client.py: RabbitMQ producer/consumer used to communicate with the Edge Cluster broker.

API Layer

Defined under app/api/v1/:

• faas.py: Declares faas_router and exports Prometheus metrics and collectors consumed by main.py.
• nano_pb2.py / nanopb_pb2.py: Protocol Buffer-related modules used for message or payload structures.

Data Models

Defined under app/models/:

• faas.py: FaaS request/response data structures and internal communication models between function calls.
• daas.py: DaaS-related models complementing FaaS flows.

Tests

Located under app/test/:

• test_faas.py, test_pyexec.py, test_cexec.py, test_rabbitmq_client.py: Unit tests validating API and core module behaviours.

Entry Scripts

• app/entrypoint.sh: Shell entrypoint for container or runtime startup sequencing.