build(flake): Use treefmt as nix formatter

This allows us to also keep markdown and other documents, that aren't
nix, formatted.

1 files changed, 14 insertions, 4 deletions

diff --git a/flake.nix b/flake.nix
index dc63ea9..c7af7b4 100644
--- a/flake.nix
+++ b/flake.nix
@@ -7,6 +7,13 @@
 
     library.url = "git+https://git.vhack.eu/vhack.eu/nix-library?ref=prime";
 
+    treefmt-nix = {
+      url = "github:numtide/treefmt-nix";
+      inputs = {
+        nixpkgs.follows = "nixpkgs";
+      };
+    };
+
     # inputs for following
     systems = {
       url = "github:nix-systems/x86_64-linux"; # only evaluate for this system
@@ -76,6 +83,7 @@
     nixpkgs,
     nixpkgs-unstable,
     library,
+    treefmt-nix,
     # modules
     simple-nixos-mailserver,
     impermanence,
@@ -107,6 +115,7 @@
     vhackPackages = import ./pkgs {inherit pkgs nixLib;};
 
     inherit (library) nixLib;
+    treefmtEval = import ./treefmt.nix {inherit treefmt-nix pkgs;};
   in {
     nixosConfigurations."server1" = nixpkgs.lib.nixosSystem {
       system = "x86_64-linux";
@@ -119,15 +128,17 @@
         ];
     };
 
-    checks."${system}" = tests;
+    checks."${system}" = nixLib.warnMerge tests {
+      formatting =
+        treefmtEval.config.build.check self;
+    } "the flake checks";
 
     packages."${system}" = vhackPackages;
+    formatter."${system}" = treefmtEval.config.build.wrapper;
 
     devShells."${system}" = {
       default = pkgs.mkShell {
         packages = with pkgs; [
-          alejandra
-
           # used for certificate generation in the taskserver setup
           gnutls
 
@@ -138,6 +149,5 @@
         ];
       };
     };
-    formatter."${system}" = pkgs.alejandra;
   };
 }