# Foxy 🦊
[](https://github.com/johan-steffens/foxy/actions/workflows/publish.yml)
[](https://crates.io/crates/foxy-io)
[](https://crates.io/crates/foxy-io)
[](https://github.com/johan-steffens/foxy/blob/main/LICENSE.md)
[](https://blog.rust-lang.org/2023/06/01/Rust-1.70.0.html)
A minimal, configuration-driven, hyper-extendible Rust HTTP proxy library.
## Features
- 🛣️ **Powerful Routing**: Predicate-based routing with path patterns, HTTP methods, headers, and query matching
- 🔄 **Flexible Filters**: Pre and post-processing filters for request/response modification
- ⚙️ **Configuration Superpowers**: Layered configuration from files and environment variables
- 🌐 **Fine-grained Control**: Route-specific filter chains for precise request handling
- 🚀 **Modern Async Architecture**: Built on Tokio and Hyper for high performance
- 📦 **Lightweight Dependencies**: Minimal external dependencies for core functionality
- 🧩 **Highly Extensible**: Custom predicates and filters through trait-based design
## Quickstart
### Run the basic proxy example
```bash
git clone https://github.com/johan-steffens/foxy.git
cd foxy
crate run --example basic-proxy
```
### Run it in your code
Add Foxy as a dependency to your `Cargo.toml` file
```toml
[dependencies]
foxy-io = "..."
```
Build an instance and start the server.
```rust
use foxy::Foxy;
// Create a new Foxy instance with layered configuration
let foxy = Foxy::loader()
.with_env_vars() // Environment variables (highest priority)
.with_config_file("config.toml") // File-based config (medium priority)
.with_config_file("defaults.toml") // Defaults (lowest priority)
.build().await?;
// Start the proxy server and wait for it to complete
foxy.start().await?;
```
## Core Principles
- **Predictable Routing**: Predicate-based matching with clear priorities determines how requests are routed
- **Configurable Processing**: Route-specific and global filters for request/response modification
- **Extensibility**: Trait-based design enables custom predicates and filters
- **Configuration-Driven**: All behavior controlled via flexible configuration with sensible defaults
## Configuration
Foxy's power comes from its rich configuration system. Here's a brief overview:
```json
{
"routes": [
{
"id": "api-route",
"target": "https://api.example.com",
"filters": [
{
"type": "path_rewrite",
"config": {
"pattern": "^/api/(.*)$",
"replacement": "/v2/$1"
}
}
],
"predicates": [
{
"type_": "path",
"config": {
"pattern": "/api/*"
}
}
]
}
]
}
```
For detailed information on all configuration options, see the [Configuration Guide](./CONFIGURATION.md).
### Configuration Sources
Foxy supports multiple configuration sources with priority order:
```rust
// Build a layered configuration
let foxy = Foxy::loader()
.with_env_vars() // First priority
.with_config_file("config.json") // Second priority
.build().await?;
```
Example: `FOXY_SERVER_PORT=8080` → `server.port`
### Streaming bodies
* Foxy proxies **request and response bodies as streams** end-to-end to ensure there's no full body buffering in memory.
* Large uploads/downloads back-pressure correctly.
* Memory usage is bound only by socket buffers.
### Detailed timing metrics
* Foxy records and logs three high-resolution latencies on every call
(DEBUG level):
`[timing] <METHOD> <PATH> -> <STATUS> | total=<X> upstream=<Y> internal=<Z>`
| **total** | wall-clock time from first byte in to last byte out |
| **upstream** | time spent awaiting the target server |
| **internal** | proxy-side routing / filtering / logging (total − upstream) |
### Request and Response body logging
* `LoggingFilter` now **peeks and logs the first 1 000 bytes/characters** of every
request and response body (UTF-8-lossy).
Binary or very large payloads are safe—the remainder of the stream is forwarded
untouched.
* Please note that enabling request and response body logging will introduce additional
latency to your calls
## Development Status
- [x] Configuration System
- [x] Loader Module
- [x] Core HTTP Proxy
- [x] Predicate-based Routing
- [x] Request/Response Filters
- [ ] Additional Security Features
## License
This project is licensed under [Mozilla Public License Version 2.0](LICENSE.md)