Use cachix instead of magic-nix-cache

magic-nix-cache no longer works on x86_64 macOS runners and the upload is slow.

Author: jfroche

.github/actions/install-nix-action/action.yml

@@ -14,6 +14,9 @@ inputs:
   no-init:
     description: "Whether to install Nix without init system integration"
     default: false
+  cachix-authtoken:
+    description: "cachix authentication token"
+    default: ""
 
 runs:
   using: "composite"
@@ -30,8 +33,7 @@ runs:
         init: ${{ inputs.no-init == 'true' && 'none' || '' }}
         planner: ${{ inputs.no-init == 'true' && 'linux' || '' }}
 
-    - uses: DeterminateSystems/magic-nix-cache-action@565684385bcd71bad329742eefe8d12f2e765b39 # v13
-      if: ${{ inputs.use-cache == 'true' && !(runner.os == 'macOS' && runner.arch == 'X64') }}
+    - uses: cachix/cachix-action@v15
       with:
-        use-flakehub: false
-        use-gha-cache: true
+        name: nix-installer
+        authToken: "${{ inputs.cachix-authtoken}}"

.github/workflows/ci.yml

@@ -34,6 +34,9 @@ jobs:
 
       - name: Install Nix
         uses: ./.github/actions/install-nix-action
+        with:
+          cachix-authtoken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
+
 
       - name: Build the installer
         run: |
@@ -75,6 +78,8 @@ jobs:
 
       - name: Install Nix
         uses: ./.github/actions/install-nix-action
+        with:
+          cachix-authtoken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
 
       - name: Check rustfmt
         run: nix develop --command check-rustfmt
@@ -143,6 +148,7 @@ jobs:
       - name: Initial install
         uses: ./.github/actions/install-nix-action
         with:
+          cachix-authtoken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
           dogfood: true
           dogfood-path: ${{ steps.download-installer.outputs.download-path }}
           use-cache: false
@@ -187,6 +193,7 @@ jobs:
       - name: Repeated install
         uses: ./.github/actions/install-nix-action
         with:
+          cachix-authtoken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
           dogfood: true
           dogfood-path: ${{ steps.download-installer.outputs.download-path }}
           use-cache: false
@@ -273,6 +280,7 @@ jobs:
       - name: Initial install
         uses: ./.github/actions/install-nix-action
         with:
+          cachix-authtoken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
           dogfood: true
           dogfood-path: ${{ steps.download-installer.outputs.download-path }}
 

.github/workflows/release-script.yml

@@ -15,6 +15,8 @@ jobs:
     - name: Checkout
       uses: actions/checkout@v4
     - uses: cachix/install-nix-action@v25
+      with:
+        cachix-authtoken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
     - name: Create draft release
       # The script also depends on gh and git but those are both pre-installed on the runner
       run: nix run --inputs-from .# nixpkgs#python3 -- assemble_installer.py "${{ github.event.inputs.testing_hydra_eval_id }}"

.github/workflows/update.yml

@@ -15,6 +15,8 @@ jobs:
         uses: actions/checkout@v4
       - name: Install Nix
         uses: ./.github/actions/install-nix-action
+        with:
+          cachix-authtoken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
       - name: Check flake
         uses: DeterminateSystems/flake-checker-action@main
       - name: Update flake.lock