The Nix Flake Checker Action

This repo houses a Github Action from Determinate Systems that performs health checks on your repos' flake.lock files. Specifically, it wraps the Nix Flake Checker tool, which verifies that your root Nixpkgs inputs:

• Have been updated within the last 30 days
• Have the NixOS GitHub org as their owner
• Are from a supported Git branch

Here's an example configuration that uses flake-checker-action as part of a broader Actions workflow involving Nix.

on:
  pull_request:
  push:
    branches: [main]

jobs:
  build:
    name: Build Nix targets
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v6
      - name: Check Nix flake inputs
        uses: DeterminateSystems/flake-checker-action@main # This action
      - name: Install Nix
        uses: DeterminateSystems/determinate-nix-action@v3
      - name: Build default package
        run: nix build

Configuration

The Nix Flake Checker Action has a number of configuration parameters that you can set in the with block:

Here's an example non-default configuration:

- name: Check Nix flake inputs
  uses: DeterminateSystems/flake-checker-action@v2
  with:
    flake-lock-path: ./nix/flake.lock
    check-owner: false
    ignore-missing-flake-lock: false
    fail-mode: true