CI: Run a nix task

.forgejo/workflows/ci.yaml

@@ -1,10 +1,13 @@
 on: push
 jobs:
   Publish:
-    runs-on: docker
+    runs-on: flakes-action
     steps:
       - uses: actions/checkout@v3
         name: Checkout
       - name: Build
         run: |
-          echo "Hello World!"
+          nix build
+      - name: Run
+        run: |
+          ./result/bin/hello

.gitignore

@@ -0,0 +1 @@
+result/

flake.lock

@@ -0,0 +1,26 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1695673361,
+        "narHash": "sha256-Y8TzvhN7zBKooJrIQ0FjKZSZ0iuistIURCx89C4DPXE=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "0fbc32585c7617c1fb7b7acbb1db9f13d54c3d04",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,24 @@
+{
+  description = "A flake for building Hello World";
+
+  inputs.nixpkgs.url = github:NixOS/nixpkgs;
+
+  outputs = { self, nixpkgs }: {
+    defaultPackage.x86_64-linux =
+      with import nixpkgs { system = "x86_64-linux"; };
+      stdenv.mkDerivation {
+        name = "hello";
+        src = self;
+        buildPhase = "cc -o hello ./hello.c";
+        installPhase = "mkdir -p $out/bin; install -t $out/bin hello";
+      };
+    defaultPackage.aarch64-darwin =
+      with import nixpkgs { system = "aarch64-darwin"; };
+      stdenv.mkDerivation {
+        name = "hello";
+        src = self;
+        buildPhase = "cc -o hello ./hello.c";
+        installPhase = "mkdir -p $out/bin; install -t $out/bin hello";
+      };
+  };
+}

hello.c

@@ -0,0 +1,4 @@
+int main(void) { 
+  printf("Hello World\n"); 
+  return 0;
+}