cachix-push

A flake app to push and pin multiple store paths built by Omnix to cachix. Better than nix build ... | cachix push ....

When you pin paths, they are indexed by system and custom prefix (usually git branch). In CI, you can do this only from say main branch, thus having up-to-date cache for your primary branch and have it pinned.

Usage

Push and pin all store paths built by om ci. First, run om ci to build outputs:

# First, build the flake.
om ci run --results=om.json

This will create a JSON like:

{
  "systems": [
    "x86_64-linux"
  ],
  "result": {
    "omnix": {
      "build": {
        "byName": {
          "treefmt-check": "/nix/store/x14rcm3djs4cr9d2ih0msxw8jiwdm1yn-treefmt-check",
          "omnix-cli": "/nix/store/ci6vsd9wpd8h3mrjxf7ny4mk1ncjjprc-omnix-cli-0.1.0",
          "omnix-devshell": "/nix/store/n4ri7biinnpwx0d5s68vgni6wjlichn1-omnix-devshell",
          "rust-flake-devshell": "/nix/store/wcj64d5yv56bd728737rczxkdjwvfibs-rust-flake-devshell"
        }
      }
    },
  }
} 

(Everything under byName represents the store paths of flake output indexed by their derivation name)

Which can you pass to this program to push & pin on cache:

# Push to https://mycache.cachix.org
nix run github:juspay/cachix-push -- --cache mycache --subflake ROOT --prefix "$(git branch --show-current)" < om.json

This will output at the end what got pinned, for example:

[..]
Pinning on https://om.cachix.org
Pin main-x86_64-linux-treefmt-check => /nix/store/x14rcm3djs4cr9d2ih0msxw8jiwdm1yn-treefmt-check
Pin main-x86_64-linux-omnix-cli => /nix/store/ci6vsd9wpd8h3mrjxf7ny4mk1ncjjprc-omnix-cli-0.1.0
Pin main-x86_64-linux-omnix-devshell => /nix/store/n4ri7biinnpwx0d5s68vgni6wjlichn1-omnix-devshell
Pin main-x86_64-linux-rust-flake-devshell => /nix/store/wcj64d5yv56bd728737rczxkdjwvfibs-rust-flake-devshell

which gets reflected in the cachix UI as:

GitHub workflow example

• https://github.com/juspay/omnix/pull/340