Cache the Github workflow dependencies

Author: ibbem

.github/workflows/maven.yml

@@ -15,8 +15,12 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: cachix/install-nix-action@v18
     - uses: actions/checkout@v3
+    - name: Install Nix with cached packages
+      uses: rikhuijzer/[email protected]
+      with:
+        key: nix-${{ hashFiles('.github/workflows/maven.yml', 'default.nix', 'nix/**') }}
+        nix_file: nix/github-workflow-dependencies.nix
     - name: Build
       run: nix-build
     - name: Upload Javadoc artifact

nix/github-workflow-dependencies.nix

@@ -0,0 +1,16 @@
+{
+  sources ? import ./sources.nix,
+  system ? builtins.currentSystem,
+  pkgs ?
+    import sources.nixpkgs {
+      overlays = [];
+      config = {};
+      inherit system;
+    },
+}: let
+  DiffDetective = import ../default.nix {};
+in
+  pkgs.mkShell {
+    inputsFrom = [DiffDetective];
+    pkgs = [DiffDetective.mavenRepo];
+  }