ncps: Nix Cache Proxy Server

A high-performance proxy server that accelerates Nix dependency retrieval across your local network

What is ncps?

ncps acts as a local binary cache for Nix, fetching store paths from upstream caches (like cache.nixos.org) and storing them locally. This reduces download times and bandwidth usage, especially beneficial when multiple machines share the same dependencies.

Key Features

• Multi-upstream cache with automatic failover
• Flexible storage: local filesystem or S3-compatible (AWS S3, MinIO, etc.)
• Database support: SQLite, PostgreSQL, or MySQL/MariaDB
• High availability with Redis distributed locking for zero-downtime deployments
• Smart caching: LRU management with configurable size limits
• Secure signing: Signs cached paths with private keys for integrity
• Observability: OpenTelemetry and Prometheus metrics support
• Easy setup: Simple configuration and deployment

⚠️ Development Status & Data Safety

Important

Production Warning: The main branch and pre-release versions are under active development and should never be used in production. Your data may be lost or corrupted! Always use the latest release for production environments.

Early Stage Notice: ncps is in early development and data consistency/recovery is not guaranteed. Please maintain regular backups of your data, especially when updating ncps versions.

Quick Start

Get ncps running in minutes with Docker:

# Pull images and create storage
docker pull alpine && docker pull ghcr.io/kalbasit/ncps
docker volume create ncps-storage
docker run --rm -v ncps-storage:/storage alpine /bin/sh -c \
  "mkdir -m 0755 -p /storage/var && mkdir -m 0700 -p /storage/var/ncps && mkdir -m 0700 -p /storage/var/ncps/db"

# Initialize database
docker run --rm -v ncps-storage:/storage ghcr.io/kalbasit/ncps \
  /bin/dbmate --url=sqlite:/storage/var/ncps/db/db.sqlite up

# Start the server
docker run -d --name ncps -p 8501:8501 -v ncps-storage:/storage ghcr.io/kalbasit/ncps \
  /bin/ncps serve \
  --cache-hostname=your-ncps-hostname \
  --cache-storage-local=/storage \
  --cache-database-url=sqlite:/storage/var/ncps/db/db.sqlite \
  --cache-upstream-url=https://cache.nixos.org \
  --cache-upstream-public-key=cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=

Your cache will be available at http://localhost:8501. See the Quick Start Guide for more options including S3 storage.

Documentation

• Getting Started - Quick start guide, core concepts, and architecture
• Installation - Docker, Docker Compose, Kubernetes, Helm, NixOS
• Configuration - Complete configuration reference, storage and database options
• Deployment - Single-instance and high-availability deployment guides
• Usage - Client setup and cache management
• Operations - Monitoring, troubleshooting, backup and upgrades
• Architecture - System architecture and design details
• Development - Contributing, development setup, and testing

Installation Methods

Method	Best For	Documentation
Docker	Quick setup, single-instance	Docker Guide
Docker Compose	Automated setup with dependencies	Docker Compose Guide
Kubernetes	Production, manual K8s deployment	Kubernetes Guide
Helm Chart	Production, simplified K8s management	Helm Guide
NixOS	NixOS systems with native integration	NixOS Guide

Deployment Modes

• Single-instance: Simple deployment with local or S3 storage, SQLite or shared database
• High Availability: Multiple instances with S3 storage, PostgreSQL/MySQL, and Redis for zero-downtime operation. Note: Must enable CDC.

See the Deployment Guide for detailed setup instructions.

Support the Project

If you find ncps useful, please consider supporting its development! Sponsoring helps maintain the project, fund new features, and ensure long-term sustainability.

Contributing

Contributions are welcome! We appreciate bug reports, feature requests, documentation improvements, and code contributions.

See the Developer Guide for:

• Development setup and workflow
• Code quality standards and testing procedures
• How to submit pull requests

License

This project is licensed under the MIT License - see the LICENSE file for details.

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