AnyFS - Executive Summary

One-page overview for stakeholders and decision-makers.

What is it?

AnyFS is an open standard for pluggable virtual filesystem backends in Rust, using a Tower-style middleware pattern for composable functionality.

You get:

• A familiar std::fs-aligned API
• Composable middleware for limits, logging, and security
• Choice of storage: memory, SQLite, host filesystem, or custom

Architecture

┌─────────────────────────────────────────┐
│  FileStorage<B>                         │  ← Ergonomics (std::fs API)
├─────────────────────────────────────────┤
│  Middleware (composable):               │
│    Quota<B>                             │  ← Quotas
│    Restrictions<B>                      │  ← Security
│    Tracing<B>                           │  ← Audit
├─────────────────────────────────────────┤
│  Fs                                     │  ← Storage
└─────────────────────────────────────────┘

Why does it matter?

Key design points

• Two-crate structure

  • anyfs-backend: trait contract
  • anyfs: backends + middleware + ergonomic wrapper

• Middleware pattern (like Axum/Tower)

  • Each middleware has one job
  • Compose only what you need
  • Complete separation of concerns

• std::fs alignment

  • Familiar method names
  • Core traits use &Path; FileStorage/FsExt accept impl AsRef<Path> for ergonomics

• Developer experience first

  • Make storage composition easy, safe, and enjoyable to use

Quick example

#![allow(unused)]
fn main() {
use anyfs::{MemoryBackend, QuotaLayer, RestrictionsLayer, FileStorage};

// Layer-based composition
let backend = MemoryBackend::new()
    .layer(QuotaLayer::builder()
        .max_total_size(100 * 1024 * 1024)
        .build())
    .layer(RestrictionsLayer::builder()
        .deny_permissions()
        .build());

let fs = FileStorage::new(backend);

fs.create_dir_all("/documents")?;
fs.write("/documents/hello.txt", b"Hello!")?;
}

Status

For details, see Design Overview.