[INTT-41] Add generic pre-commit hooks

README.md

@@ -60,7 +60,7 @@ To use the standards in a new project, create the following
         # Specify a default devshell for the project; other options are
         # documented in the devshells section below.
         #
-        # devShells.default = inputs'.famedly-engineering-standards.devShells.rust;
+        # devShells.default = inputs'.famedly-engineering-standards.devShells.standards;
 
         famedly.standards = {
           # Read module documentation for further details, but most
@@ -87,6 +87,7 @@ The following basic devshells are available:
 
 | Name      | Purpose |
 | --------- | ------- |
+| standards | Contains basic tools and configuration used by all famedly projects. |
 | rust      | Contains the Famedly Rust toolchain, and everything required to build Rust projects. |
 | k8s       | Contains miscellaneous k8s-related utilities, especially useful on MacOS. |
 
@@ -154,3 +155,35 @@ to ensure that most developers can interact with this repository.
 If you struggle creating a completely new file, ask someone with more
 nix experience to help you hook this into the filegen-activate
 command.
+
+### Adding pre-commit hooks
+
+Pre-commit hooks are intended to be *very* fast to execute. These
+should be ergonomic to run every time you create a git commit - when
+doing rebase operations, that can mean dozens in a few 100ms.
+
+As such, these should never contain expensive operations - compiling
+code is absolutely not acceptable, and even complex parsing (for
+formatting) may be pushing it.
+
+For more expensive operations, add a workflow instead, and let CI
+perform the check.
+
+---
+
+To actually add a pre-commit hook, in addition to defining the hook,
+any dependencies required **must** be added to the `prek`
+wrapper. Assuming the dependency is packaged in nixpkgs, this is quite
+easy:
+
+```nix
+{
+  config.perSystem = { pkgs, ... }: {
+    prek-pre-commit.package.runtimePkgs = [ pkgs.foobar ];
+  };
+}
+```
+
+More complex modifications to the `prek` wrapper are possible too,
+refer to our [wrapper module provider](https://birdeehub.github.io/nix-wrapper-modules/modules/default.html)
+for details.

flake.nix

@@ -20,6 +20,11 @@
       url = "github:oxalica/rust-overlay";
       inputs.nixpkgs.follows = "nixpkgs";
     };
+
+    wrappers = {
+      url = "github:BirdeeHub/nix-wrapper-modules";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
   };
 
   outputs =
@@ -37,7 +42,10 @@
 
         flakeModules = rec {
           filegen = ./nix/modules/filegen.nix;
-          prek-pre-commit = importApply ./nix/modules/prek-pre-commit.nix { inherit filegen; };
+          prek-pre-commit = importApply ./nix/modules/prek-pre-commit.nix {
+            inherit filegen;
+            inherit (inputs) wrappers;
+          };
         };
 
         default = importApply ./nix (args // { inherit importApply flakeModules; });

nix/default.nix

@@ -25,7 +25,20 @@ importingFlake: {
   ];
 
   # TODO: Break this out into a proper ecosystem-oriented module.
-  perSystem = { pkgs, lib, ... }: {
-    devshells.k8s.packages = lib.attrValues { inherit (pkgs) kubectl kubelogin-oidc kubetui; };
-  };
+  perSystem =
+    {
+      config,
+      pkgs,
+      lib,
+      ...
+    }:
+    {
+      devshells.k8s = {
+        packages = lib.attrValues { inherit (pkgs) kubectl kubelogin-oidc kubetui; };
+
+        # TODO: Find a better way to inherit devshell
+        # configurations.
+        commands = lib.filter (command: command.name != "menu") config.devshells.standards.commands;
+      };
+    };
 }

nix/general/default.nix

@@ -3,9 +3,15 @@
   lib,
   importApply,
   ...
-}:
+}@args:
 importingFlake: {
-  imports = [ ./action-versions.nix ];
+  imports = [
+    ./action-versions.nix
+    (importApply ./devshell.nix args)
+    (importApply ./pre-commit-hooks.nix args)
+
+    ./workflows/check-pre-commit-hooks.nix
+  ];
 
   config.perSystem =
     { config, ... }:

nix/general/devshell.nix

@@ -0,0 +1,29 @@
+{
+  flakeModules,
+  inputs,
+  lib,
+  ...
+}:
+importingFlake: {
+  config.perSystem = { config, ... }: {
+    devshells.standards = {
+      name = lib.mkDefault "engineering-standards";
+
+      commands = [
+        {
+          name = "prek";
+          help = "Run pre-commit hooks on currently staged changes";
+          category = "[[lints and checks]]";
+          package = config.prek-pre-commit.package.wrapper;
+        }
+
+        {
+          name = "prek -s main -o HEAD";
+          help = "Run pre-commit hooks on all commits in the current branch";
+          category = "[[lints and checks]]";
+          package = config.prek-pre-commit.package.wrapper;
+        }
+      ];
+    };
+  };
+}