[!CAUTION] These design documents are generated by AI and may not be fully accurate or complete. They are intended to provide a starting point for understanding the system architecture and design patterns used in the template-fastapi application.
Internal Design Specification
Architecture Overview
The template-fastapi application follows a layered architecture pattern with clear separation of concerns, enabling maintainability, testability, and scalability.
System Architecture
graph TB
Client[Client Applications]
LB[Load Balancer]
subgraph "FastAPI Application"
App[app.py - Main Application]
Router[Router Layer]
Logic[Business Logic Layer]
Repo[Repository Layer]
Models[Data Models]
end
subgraph "Azure Cloud Services"
CosmosDB[(Azure CosmosDB)]
BlobStorage[(Azure Blob Storage)]
OpenAI[Azure OpenAI]
Speech[Azure AI Speech]
AIFoundry[Azure AI Foundry]
AppInsights[Application Insights]
end
Client --> LB
LB --> App
App --> Router
Router --> Logic
Logic --> Repo
Repo --> Models
Repo --> CosmosDB
Repo --> BlobStorage
Repo --> OpenAI
Repo --> Speech
Repo --> AIFoundry
App --> AppInsights
Package Structure and Responsibilities
Core Application (template_fastapi/
)
graph LR
subgraph "Application Core"
App[app.py]
Core[core.py]
Settings[settings/]
OpenTel[opentelemetry.py]
end
subgraph "API Layer"
Routers[routers/]
Items[items.py]
Files[files.py]
Foodies[foodies.py]
Speeches[speeches.py]
Chats[chats.py]
Demos[demos.py]
Agents[agents/]
end
subgraph "Data Layer"
Models[models/]
Repositories[repositories/]
Internals[internals/]
end
subgraph "Infrastructure"
Templates[templates/]
Static[static files]
end
App --> Routers
App --> Settings
App --> OpenTel
Routers --> Models
Routers --> Repositories
Package Responsibilities
app.py
- Application Bootstrap
- FastAPI application initialization
- Router registration and configuration
- Middleware setup (CORS, logging, monitoring)
- Azure Application Insights integration
- Telemetry and observability configuration
routers/
- API Endpoint Handlers
- Purpose: HTTP request routing and response handling
- Responsibilities:
- Request validation using Pydantic models
- HTTP status code management
- Error handling and exception transformation
- Business logic delegation to repositories
- Response formatting
repositories/
- Data Access Layer
- Purpose: External service integration and data persistence
- Responsibilities:
- Azure service client management
- Data transformation between external APIs and internal models
- Connection pooling and retry logic
- Service-specific error handling
models/
- Data Models
- Purpose: Data structure definitions and validation
- Responsibilities:
- Pydantic model definitions for request/response
- Data validation rules and constraints
- Serialization/deserialization logic
- Type safety enforcement
settings/
- Configuration Management
- Purpose: Environment-based configuration
- Responsibilities:
- Environment variable loading
- Service connection configuration
- Feature flag management
- Logging configuration
Service Communication Flow
Request Processing Flow
sequenceDiagram
participant Client
participant Router
participant Repository
participant Azure
participant Logger
Client->>Router: HTTP Request
Router->>Logger: Log request start
Router->>Router: Validate request data
Router->>Repository: Call business method
Repository->>Azure: External service call
Azure-->>Repository: Service response
Repository->>Repository: Transform data
Repository-->>Router: Return result
Router->>Logger: Log request completion
Router-->>Client: HTTP Response
Error Handling Flow
sequenceDiagram
participant Client
participant Router
participant Repository
participant Azure
participant Logger
Client->>Router: HTTP Request
Router->>Repository: Call method
Repository->>Azure: Service call
Azure-->>Repository: Service error
Repository->>Logger: Log error details
Repository->>Repository: Transform to application error
Repository-->>Router: Raise HTTPException
Router->>Logger: Log error response
Router-->>Client: Error response (4xx/5xx)
Agent System Architecture
LangGraph Agent Flow
flowchart TD
Request[User Request] --> LangRouter[LangGraph Router]
LangRouter --> ToolSelector[Tool Selection]
ToolSelector --> Calculator[Calculator Tool]
ToolSelector --> TimeQuery[Time Query Tool]
ToolSelector --> WebSearch[Web Search Tool]
Calculator --> MathExecution[Math Expression Eval]
TimeQuery --> TimeAPI[System Time API]
WebSearch --> SearchAPI[External Search API]
MathExecution --> Response[Formatted Response]
TimeAPI --> Response
SearchAPI --> Response
Response --> LangRouter
LangRouter --> Client[Client Response]
Azure AI Foundry Agent Flow
sequenceDiagram
participant Client
participant Router
participant Repository
participant AIFoundry
participant Thread
Client->>Router: Create Agent Request
Router->>Repository: Create Agent
Repository->>AIFoundry: POST /agents
AIFoundry-->>Repository: Agent Created
Repository-->>Router: Agent Response
Router-->>Client: Agent Details
Client->>Router: Chat Request
Router->>Repository: Chat with Agent
Repository->>Thread: Retrieve/Create Thread
Repository->>AIFoundry: POST /threads/{id}/messages
AIFoundry-->>Repository: Message Response
Repository-->>Router: Chat Response
Router-->>Client: AI Response
Data Models and Relationships
Core Entity Relationships
erDiagram
Item ||--o{ ItemSearch : searchable
Restaurant ||--o{ RestaurantLocation : "has location"
Restaurant ||--o{ RestaurantEmbedding : "has embedding"
File ||--|| BlobMetadata : "stored as"
TranscriptionJob ||--o{ TranscriptionFile : "produces"
TranscriptionJob ||--|| AudioSource : "processes"
Agent ||--o{ Thread : "manages"
Thread ||--o{ Message : "contains"
ChatSession ||--o{ WebSocketConnection : "maintains"
Item {
string id PK
string name
string description
float price
float tax
}
Restaurant {
string id PK
string name
string description
string cuisine_type
float latitude
float longitude
float rating
}
File {
string name PK
int size
string content_type
datetime last_modified
string url
}
Agent {
string id PK
string name
string model
string instructions
datetime created_at
}
Thread {
string id PK
string agent_id FK
datetime created_at
json metadata
}
Service Integration Patterns
Repository Pattern Implementation
classDiagram
class BaseRepository {
<<abstract>>
+logger: Logger
+settings: Settings
+initialize_client()
+handle_errors()
}
class ItemRepository {
+cosmos_client: CosmosClient
+list_items(limit, offset)
+get_item(id)
+create_item(item)
+update_item(id, item)
+delete_item(id)
+search_items(query)
}
class FileRepository {
+blob_client: BlobServiceClient
+list_files(prefix)
+upload_file(name, data)
+download_file(name)
+delete_file(name)
+get_file_info(name)
}
class RestaurantRepository {
+cosmos_client: CosmosClient
+openai_client: OpenAIClient
+list_restaurants(limit, offset)
+search_restaurants(query, k)
+find_nearby_restaurants(lat, lng, radius)
}
BaseRepository <|-- ItemRepository
BaseRepository <|-- FileRepository
BaseRepository <|-- RestaurantRepository
Configuration Management Pattern
classDiagram
class BaseSettings {
<<abstract>>
+env_prefix: str
+validate_settings()
}
class AzureOpenAISettings {
+endpoint: str
+api_key: str
+api_version: str
+model_chat: str
+model_embedding: str
}
class AzureCosmosDBSettings {
+connection_string: str
+database_name: str
+container_name: str
}
class LoggingSettings {
+log_level: str
+configure_logging()
+get_logger(name)
}
BaseSettings <|-- AzureOpenAISettings
BaseSettings <|-- AzureCosmosDBSettings
BaseSettings <|-- LoggingSettings
Security and Monitoring Integration
Logging and Telemetry Flow
flowchart TD
App[FastAPI Application] --> LogConfig[Logging Configuration]
LogConfig --> StructuredLogs[Structured Logging]
App --> OpenTelemetry[OpenTelemetry SDK]
OpenTelemetry --> Traces[Distributed Tracing]
OpenTelemetry --> Metrics[Custom Metrics]
StructuredLogs --> AppInsights[Application Insights]
Traces --> AppInsights
Metrics --> AppInsights
AppInsights --> Dashboard[Azure Dashboard]
AppInsights --> Alerts[Alert Rules]
LogConfig --> Console[Console Output]
LogConfig --> FileOutput[File Output]
Environment-based Configuration
flowchart LR
EnvTemplate[.env.template] --> LocalEnv[.env]
EnvTemplate --> ProdEnv[Production Environment]
LocalEnv --> DevConfig[Development Settings]
ProdEnv --> ProdConfig[Production Settings]
DevConfig --> LocalServices[Local/Mock Services]
ProdConfig --> AzureServices[Azure Cloud Services]
DevConfig --> DebugLogging[DEBUG Logging]
ProdConfig --> InfoLogging[INFO Logging]
Performance and Scalability Considerations
Caching Strategy
graph TB
Request[Client Request] --> FastAPI[FastAPI Router]
FastAPI --> Cache{Cache Hit?}
Cache -->|Yes| CacheReturn[Return Cached Response]
Cache -->|No| Repository[Repository Layer]
Repository --> Azure[Azure Services]
Azure --> Repository
Repository --> CacheStore[Store in Cache]
CacheStore --> Response[Return Response]
CacheReturn --> Client[Client Response]
Response --> Client
Connection Pooling
graph LR
App[Application Startup] --> PoolInit[Initialize Connection Pools]
PoolInit --> CosmosPool[CosmosDB Pool]
PoolInit --> BlobPool[Blob Storage Pool]
PoolInit --> OpenAIPool[OpenAI Pool]
Request[Request Handler] --> PoolManager[Connection Pool Manager]
PoolManager --> CosmosPool
PoolManager --> BlobPool
PoolManager --> OpenAIPool
CosmosPool --> CosmosOps[Database Operations]
BlobPool --> BlobOps[Storage Operations]
OpenAIPool --> AIOps[AI Operations]
Testing Strategy
Test Architecture
graph TB
subgraph "Test Layers"
UnitTests[Unit Tests]
IntegrationTests[Integration Tests]
E2ETests[End-to-End Tests]
end
subgraph "Test Utilities"
Fixtures[Pytest Fixtures]
Mocks[Mock Services]
TestClient[FastAPI TestClient]
end
subgraph "Coverage Areas"
RouterTests[Router Layer Tests]
RepoTests[Repository Tests]
ModelTests[Model Validation Tests]
CoreTests[Core Logic Tests]
end
UnitTests --> RouterTests
UnitTests --> RepoTests
UnitTests --> ModelTests
UnitTests --> CoreTests
Fixtures --> UnitTests
Mocks --> UnitTests
TestClient --> IntegrationTests
This internal design specification provides a comprehensive view of the application's architecture, data flow, and component interactions, enabling developers to understand and extend the system effectively.