---
title: Overview
description: Shared utilities, configuration loaders, and system abstractions in Vane.
icon: Hammer
---
The `common` module serves as the foundational utility library for the Vane project. It provides thread-safe configuration management, network utility functions, and system-level abstractions used across all layers (L4, L4+, and L7) and the bootstrap sequence.
## Core Pillars
The module is organized into three specialized sub-modules:
| Sub-module | Responsibility |
| :--------------------------------- | :------------------------------------------------------------------------------ |
| [`sys`](./common/system) | Lifecycle management, file-system watchers, and OS-specific resource detection. |
| [`net`](./common/network) | IP validation, address parsing, and port availability checking. |
| [`config`](./common/configuration) | Environment variable loading and atomic configuration file reading. |
## Design Principles
1. **Thread Safety**: Most utilities are designed to be used in concurrent contexts, utilizing atomic operations where necessary.
2. **Abstraction**: It masks platform-specific differences (especially in the `sys` module) to provide a unified API for the rest of the engine.
3. **Fail-Fast**: Configuration loaders are designed to halt execution if critical environmental prerequisites are not met.
## Usage in the Engine
The `common` utilities are imported globally throughout the codebase. For example, environment variables are accessed via a centralized loader to ensure consistency:
```rust
use crate::common::config::env_loader;
let port = env_loader::get_env("PORT", "3333".to_string());
```
<Callout type="info" title="Centralized Source of Truth">
By centralizing these utilities, Vane ensures that logic like "how to detect free memory" or "how
to validate an IP" is implemented correctly once and reused everywhere, reducing the surface area
for bugs.
</Callout>
<Callout type="idea">
Explore the dedicated guides for [System](./common/system), [Network](./common/network), and
[Configuration](./common/configuration) utilities.
</Callout>