Use the module system

.pre-commit-config.yaml

@@ -1,6 +1,18 @@
-repos:
-   - repo: .pre-commit-hooks/
-     rev: master
-     hooks:
-      -   id: shellcheck
-      -   id: canonix
+# DO NOT MODIFY
+# This file was generated by nix-pre-commit-hooks
+{
+  "repos": [
+    {
+      "hooks": [
+        {
+          "id": "canonix"
+        },
+        {
+          "id": "shellcheck"
+        }
+      ],
+      "repo": ".pre-commit-hooks/",
+      "rev": "master"
+    }
+  ]
+}

CHANGELOG.md

@@ -0,0 +1,34 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is loosely based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
+and is a rolling release.
+
+## 2019-10-02
+
+### Added
+
+- The `run` derivation now uses [gitignore](https://github.com/hercules-ci/gitignore#readme)
+
+- Custom hooks can now be added
+
+### Changed
+
+- Hooks configuration is now module-based (using the module system, like NixOS).
+  `.pre-commit-config.yaml` is now obsolete with `nix-pre-commit-hooks`. Translate it to the `hooks` argument. For example:
+
+  ```
+  pre-commit-check = nix-pre-commit-hooks.run {
+    src = ./.;
+    hooks = {
+      elm-format.enable = true;
+      ormolu.enable = true;
+      shellcheck.enable = true;
+    };
+  };
+  ```
+
+### Fixed
+
+- Some small improvements to the installation script (`shellHook`)

README.md

@@ -17,39 +17,32 @@ The goal is to manage these hooks with Nix and solve the following:
 
 # Installation & Usage
 
-1. Create `.pre-commit-config.yaml` with hooks you want to run in your git repository:
-   ```yaml
-   repos:
-   - repo: .pre-commit-hooks/
-     rev: master
-     hooks:
-      -   id: ormolu
-      -   id: shellcheck
-      -   id: elm-format
-   ```
-
-2. (optional) Use binary caches to avoid compilation:
+1. (optional) Use binary caches to avoid compilation:
 
    ```bash
    $ nix-env -iA cachix -f https://cachix.org/api/v1/install
    $ cachix use hercules-ci
    ```
 
-3. Integrate hooks to be built as part of `default.nix`:
+2. Integrate hooks to be built as part of `default.nix`:
    ```nix
     let
-      inherit (import (builtins.fetchTarball "https://github.com/hercules-ci/gitignore/tarball/master" {})) gitignoreSource;
       nix-pre-commit-hooks = import (builtins.fetchTarball "https://github.com/hercules-ci/nix-pre-commit-hooks/tarball/master");
     in {
       pre-commit-check = nix-pre-commit-hooks.run {
-        src = gitignoreSource ./.;
+        src = ./.;
+        hooks = {
+          elm-format.enable = true;
+          ormolu.enable = true;
+          shellcheck.enable = true;
+        };
       };
     }
    ```
 
    Run `$ nix-build -A pre-commit-check` to perform the checks as a Nix derivation.
 
-2. Integrate hooks to prepare environment as part of `shell.nix`:
+3. Integrate hooks to prepare environment as part of `shell.nix`:
    ```nix
     (import <nixpkgs> {}).mkShell {
       inherit ((import ./. {}).pre-commit-check) shellHook;
@@ -109,6 +102,9 @@ eval "$shellHook"
 
 Everyone is encouraged to add new hooks.
 
+<!-- TODO generate option docs -->
+Have a look at the [existing hooks](modules/hooks.nix) and the [options](modules/pre-commit.nix).
+
 There's no guarantee the hook will be accepted, but the general guidelines are:
 
 - Nix closure of the tool should be small e.g. `< 50MB`

modules/all-modules.nix

@@ -0,0 +1,7 @@
+{
+  imports =
+    [
+      ./pre-commit.nix
+      ./hooks.nix
+    ];
+}

modules/hooks.nix

@@ -0,0 +1,83 @@
+{ config, lib, pkgs, ... }:
+let
+  inherit (config.pre-commit) tools;
+in {
+  config.pre-commit.hooks =
+    {
+      hlint =
+        {
+          name = "hlint";
+          description =
+            "HLint gives suggestions on how to improve your source code.";
+          entry = "${tools.hlint}/bin/hlint";
+          files = "\\.l?hs$";
+        };
+      ormolu =
+        {
+          name = "ormolu";
+          description = "Haskell code prettifier.";
+          entry = "${tools.ormolu}/bin/ormolu --mode inplace";
+          files = "\\.l?hs$";
+        };
+      hindent =
+        {
+          name = "hindent";
+          description = "Haskell code prettifier.";
+          entry = "${tools.hindent}/bin/hindent";
+          files = "\\.l?hs$";
+        };
+      cabal-fmt =
+        {
+          name = "cabal-fmt";
+          description = "Format Cabal files";
+          entry = "${tools.cabal-fmt}/bin/cabal-fmt --inplace";
+          files = "\\.cabal$";
+        };
+      canonix =
+        {
+          name = "canonix";
+          description = "Nix code prettifier.";
+          entry = "${tools.canonix}/bin/canonix";
+          files = "\\.nix$";
+        };
+      nixfmt =
+        {
+          name = "nixfmt";
+          description = "Nix code prettifier.";
+          entry = "${tools.nixfmt}/bin/nixfmt";
+          files = "\\.nix$";
+        };
+      nixpkgs-fmt =
+        {
+          name = "nixpkgs-fmt";
+          description = "Nix code prettifier.";
+          entry = "${tools.nixpkgs-fmt}/bin/nixpkgs-fmt -i";
+          files = "\\.nix$";
+        };
+      elm-format =
+        {
+          name = "elm-format";
+          description = "Format Elm files";
+          entry =
+            "${tools.elm-format}/bin/elm-format --yes --elm-version=0.19";
+          files = "\\.elm$";
+        };
+      shellcheck =
+        {
+          name = "shellcheck";
+          description = "Format shell files";
+          types =
+            [
+              "bash"
+            ];
+          entry = "${tools.shellcheck}/bin/shellcheck";
+        };
+      terraform-format =
+        {
+          name = "terraform-format";
+          description = "Format terraform (.tf) files";
+          entry = "${tools.terraform-fmt}/bin/terraform-fmt";
+          files = "\\.tf$";
+        };
+    };
+}