nixcp/README.md

Uploads stuff to your s3 binary cache, but skip stuff that exist on upstream caches to save you space and time. Unlike nix copy, we also upload build dependencies meaning you just say the package or store path and we figure out the rest. Specify upstream caches to check against with -u (can be specified multiple times, cache.nixos.org is always included).

Usage

Example:

nixcp --bucket nixcache --signing-key ~/cache-priv-key.pem --endpoint https://s3.cy7.sh -u https://nix-community.cachix.org push github:cything/nixcp/2025-04-12

The signing key is generated with:

nix-store --generate-binary-cache-key nixcache.cy7.sh cache-priv-key.pem cache-pub-key.pem

AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY environment variables should be set with your s3 credentials.

Usage: nixcp push [OPTIONS] --bucket <bucket name> --signing-key <SIGNING_KEY> [PATH]...

Arguments:
  [PATH]...  Path to upload e.g. ./result or /nix/store/y4qpcibkj767szhjb58i2sidmz8m24hb-hello-2.12.1

Options:
      --bucket <bucket name>
          The s3 bucket to upload to
  -u, --upstream <nixcache.example.com>
          Upstream cache to check against. Can be specified multiple times. cache.nixos.org is always included
      --signing-key <SIGNING_KEY>
          Path to the file containing signing key e.g. ~/cache-priv-key.pem
      --region <REGION>
          If unspecified, will get it form AWS_DEFAULT_REGION envar or default to us-east-1
      --endpoint <ENDPOINT>
          If unspecifed, will get it from AWS_ENDPOINT envar e.g. https://s3.example.com
      --skip-signature-check
          
  -h, --help
          Print help

Install with nix

nix profile install github:cything/nixcp

Or run without installing:

nix run github:cything/nixcp

Separate arguments with -- to pass them through to nixcp like so:

nix run github:cything/nixcp -- --help