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GopherGate/BACKEND_ARCHITECTURE.md
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chore: rebrand project to GopherGate
Updated all naming from LLM Proxy to GopherGate. Implemented new CSS-based branding and updated Go module/binary naming.
2026-03-19 13:37:05 -04:00

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# Backend Architecture (Go)
The GopherGate backend is implemented in Go, focusing on high performance, clear concurrency patterns, and maintainability.
## Core Technologies
- **Runtime:** Go 1.22+
- **Web Framework:** [Gin Gonic](https://github.com/gin-gonic/gin) - Fast and lightweight HTTP routing.
- **Database:** [sqlx](https://github.com/jmoiron/sqlx) - Lightweight wrapper for standard `database/sql`.
- **SQLite Driver:** [modernc.org/sqlite](https://modernc.org/sqlite) - CGO-free SQLite implementation for ease of cross-compilation.
- **Config:** [Viper](https://github.com/spf13/viper) - Robust configuration management supporting environment variables and files.
- **Metrics:** [gopsutil](https://github.com/shirou/gopsutil) - System-level resource monitoring.
## Project Structure
```text
├── cmd/
│ └── gophergate/ # Entry point (main.go)
├── internal/
│ ├── config/ # Configuration loading and validation
│ ├── db/ # Database schema, migrations, and models
│ ├── middleware/ # Auth and logging middleware
│ ├── models/ # Unified request/response structs
│ ├── providers/ # LLM provider implementations (OpenAI, Gemini, etc.)
│ ├── server/ # HTTP server, dashboard handlers, and WebSocket hub
│ └── utils/ # Common utilities (registry, pricing, etc.)
└── static/ # Frontend assets (served by the backend)
```
## Key Components
### 1. Provider Interface (`internal/providers/provider.go`)
Standardized interface for all LLM backends. Implementations handle mapping between the unified format and provider-specific APIs (OpenAI, Gemini, DeepSeek, Grok).
### 2. Model Registry & Pricing (`internal/utils/registry.go`)
Integrates with `models.dev/api.json` to provide real-time model metadata and pricing.
- **Fuzzy Matching:** Supports matching versioned model IDs (e.g., `gpt-4o-2024-08-06`) to base registry entries.
- **Automatic Refreshes:** The registry is fetched at startup and refreshed every 24 hours via a background goroutine.
### 3. Asynchronous Logging (`internal/server/logging.go`)
Uses a buffered channel and background worker to log every request to SQLite without blocking the client response. It also broadcasts logs to the WebSocket hub for real-time dashboard updates.
### 4. Session Management (`internal/server/sessions.go`)
Implements HMAC-SHA256 signed tokens for dashboard authentication. Tokens secure the management interface while standard Bearer tokens are used for LLM API access.
### 5. WebSocket Hub (`internal/server/websocket.go`)
A centralized hub for managing WebSocket connections, allowing real-time broadcast of system events, system metrics, and request logs to the dashboard.
## Concurrency Model
Go's goroutines and channels are used extensively:
- **Streaming:** Each streaming request uses a goroutine to read and parse the provider's response, feeding chunks into a channel for SSE delivery.
- **Logging:** A single background worker processes the `logChan` to perform serial database writes.
- **WebSocket:** The `Hub` runs in a dedicated goroutine, handling registration and broadcasting.
- **Maintenance:** Background tasks handle registry refreshes and status monitoring.
## Security
- **Encryption Key:** A mandatory 32-byte key is used for both session signing and encryption of sensitive data.
- **Auth Middleware:** Scoped to `/v1` routes to verify client API keys against the database.
- **Bcrypt:** Passwords for dashboard users are hashed using Bcrypt with a work factor of 12.
- **Database Hardening:** Automatic migrations ensure the schema is always current with the code.