WIP: build: add Nix flake infrastructure with unified tooling and formatting

.github/workflows/nix.yaml

@@ -0,0 +1,61 @@
+---
+name: nix
+on:
+  push:
+  pull_request:
+permissions:
+  contents: read
+  pull-requests: read
+concurrency:
+  group: ${{ github.workflow }} @ ${{ github.event.pull_request.head.label || github.head_ref || github.ref }}
+  cancel-in-progress: true
+jobs:
+  test-go-versions:
+    strategy:
+      fail-fast: false
+      matrix:
+        go-version: ['124', '125']
+        os:
+          - system: x86_64-linux
+            runs-on: ubuntu-24.04
+          - system: aarch64-darwin
+            runs-on: macos-14
+    runs-on: ${{ matrix.os.runs-on }}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v5
+      - name: Install Nix
+        uses: cachix/install-nix-action@v30
+        with:
+          extra_nix_config: |
+            accept-flake-config = true
+      - name: Setup Cachix
+        uses: cachix/cachix-action@v15
+        with:
+          name: devenv
+      - name: Build with Go 1.${{ matrix.go-version }} on ${{ matrix.os.system }}
+        run: nix build .#packages.${{ matrix.os.system }}.go-jsonschema-go${{ matrix.go-version }} --print-build-logs
+      - name: Test with Go 1.${{ matrix.go-version }} on ${{ matrix.os.system }}
+        run: nix build .#checks.${{ matrix.os.system }}.tests-go${{ matrix.go-version }} --print-build-logs
+      - name: Upload coverage to Codecov
+        if: matrix.go-version == '125' && matrix.os.system == 'x86_64-linux'
+        uses: codecov/codecov-action@v5
+        with:
+          files: ./result/coverage.out
+          fail_ci_if_error: false
+  qa:
+    runs-on: ubuntu-24.04
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v5
+      - name: Install Nix
+        uses: cachix/install-nix-action@v30
+        with:
+          extra_nix_config: |
+            accept-flake-config = true
+      - name: Setup Cachix
+        uses: cachix/cachix-action@v15
+        with:
+          name: devenv
+      - name: Run Nix flake checks
+        run: nix flake check --print-build-logs --show-trace

.gitignore

@@ -10,3 +10,7 @@ mise.toml.tmp
 dist/
 output/
 vendor/
+.direnv
+result
+.pre-commit-config.yaml
+*.log

.goreleaser.yaml

@@ -24,18 +24,18 @@ archives:
 checksum:
   name_template: checksums.txt
 snapshot:
-  version_template: "{{ incpatch .Version }}-next"
+  version_template: '{{ incpatch .Version }}-next'
 changelog:
   sort: asc
   filters:
     exclude:
-      - "^docs:"
-      - "^test:"
+      - '^docs:'
+      - '^test:'
 release:
   github:
     owner: omissis
     name: go-jsonschema
-  name_template: "{{ .Tag }}"
+  name_template: '{{ .Tag }}'
   prerelease: auto
 brews:
   - name: go-jsonschema

.rules/yamllint.yaml

@@ -12,3 +12,4 @@ ignore: |
   **/node_modules/**
   **/helm_chart/**
   **/.github/**
+  .pre-commit-config.yaml

README.md

@@ -20,7 +20,8 @@ along with unmarshalling code that validates the input JSON according to the sch
 
 ## Installing
 
-* **Download**: Get a release [here](https://github.com/atombender/go-jsonschema/releases).
+* **Download**: Get a release from the
+  [releases page](https://github.com/atombender/go-jsonschema/releases).
 
 * **Install from source**: To install with Go 1.23+:
 
@@ -42,6 +43,40 @@ This project makes use of [go workspaces](https://go.dev/ref/mod#workspaces) in
 generated code during development while keeping the codebase as tidy and maintainable as possible.
 It's an unusual choice, but it allows to not only test the code-generation logic, but also the generated code itself.
 
+## Nix Development Environment
+
+This project uses [Nix](https://nixos.org/) for reproducible development environments and CI/CD.
+Nix solves dependency management across different systems, ensuring consistent builds and tests regardless of your
+local setup.
+
+### Quick Start
+
+```shell
+# Enter development shell with all tools
+nix develop
+
+# Run all checks (tests, lints, formatting)
+nix flake check
+
+# Run specific checks
+nix build .#checks.x86_64-linux.tests-go125       # Integration tests
+nix build .#checks.x86_64-linux.lint-golang       # Go linting
+nix build .#checks.x86_64-linux.build-goreleaser  # GoReleaser build
+
+# Format code
+nix fmt
+
+# Test CI workflows locally
+nix run .#test-ci
+```
+
+### Why Nix?
+
+- **Reproducible builds**: Same dependencies across all environments (dev, CI, production)
+- **Hermetic testing**: Tests run in isolated sandboxes with no external network access
+- **Multi-version support**: Test against Go 1.24 and 1.25 simultaneously
+- **No Docker required**: Native support for NixOS and other Linux distributions
+
 ## Usage
 
 At its most basic:
@@ -76,9 +111,10 @@ Note the flag format:
 
 ### Regenerating tests' golden files
 
-It sometimes happen that new features or bug fixes to the library require regenerating the tests' golden files, here's how to do it:
+It sometimes happen that new features or bug fixes to the library require
+regenerating the tests' golden files, here's how to do it:
 
-```
+```shell
 export OVERWRITE_EXPECTED_GO_FILE="true"
 make test
 ```

codecov.yml

@@ -1,36 +1,34 @@
 ignore:
-  - "**/*.json"
-  - "**/*.md"
-  - "**/*.mod"
-  - "**/*.sum"
-  - "**/*.yaml"
-  - "**/*.yml"
-  - "**/*_test.go"
-  - "**/Dockerfile"
-  - "**/LICENSE"
-  - "**/Makefile"
-  - ".github/"
-  - ".rules/"
-  - ".vscode/"
-  - "coverage/"
-  - "dist/"
-  - "docs/"
-  - "output/"
-  - "scripts/"
-
+  - '**/*.json'
+  - '**/*.md'
+  - '**/*.mod'
+  - '**/*.sum'
+  - '**/*.yaml'
+  - '**/*.yml'
+  - '**/*_test.go'
+  - '**/Dockerfile'
+  - '**/LICENSE'
+  - '**/Makefile'
+  - .github/
+  - .rules/
+  - .vscode/
+  - coverage/
+  - dist/
+  - docs/
+  - output/
+  - scripts/
 codecov:
   require_ci_to_pass: true
   branch: main
-
 coverage:
   status:
     project:
       app:
         target: auto
-        paths: "!tests/"
+        paths: '!tests/'
       tests:
         target: auto
-        paths: "tests/"
+        paths: tests/
     patch:
       enabled: true
       target: auto