feat: Configure CI to run on self-hosted nix-builder runner

Co-authored-by: Jyumpp <11142390+Jyumpp@users.noreply.github.com>

.github/workflows/ci.yml

@@ -14,41 +14,21 @@ permissions:
 jobs:
   flake-check:
     name: Flake Check
-    runs-on: ubuntu-latest
+    runs-on: [self-hosted, nix-builder]
     steps:
       - name: Checkout repository
         uses: actions/checkout@v4
 
-      - name: Install Nix
-        uses: DeterminateSystems/nix-installer-action@main
-        with:
-          extra-conf: |
-            experimental-features = nix-command flakes
-            accept-flake-config = true
-
-      - name: Setup Nix cache
-        uses: DeterminateSystems/magic-nix-cache-action@main
-
       - name: Check flake
         run: nix flake check --show-trace --print-build-logs
 
   format-check:
     name: Format Check
-    runs-on: ubuntu-latest
+    runs-on: [self-hosted, nix-builder]
     steps:
       - name: Checkout repository
         uses: actions/checkout@v4
 
-      - name: Install Nix
-        uses: DeterminateSystems/nix-installer-action@main
-        with:
-          extra-conf: |
-            experimental-features = nix-command flakes
-            accept-flake-config = true
-
-      - name: Setup Nix cache
-        uses: DeterminateSystems/magic-nix-cache-action@main
-
       - name: Check formatting
         run: |
           nix fmt **/*.nix
@@ -60,7 +40,7 @@ jobs:
 
   build-configs:
     name: Build Key Configurations
-    runs-on: ubuntu-latest
+    runs-on: [self-hosted, nix-builder]
     strategy:
       matrix:
         config:
@@ -72,16 +52,6 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v4
 
-      - name: Install Nix
-        uses: DeterminateSystems/nix-installer-action@main
-        with:
-          extra-conf: |
-            experimental-features = nix-command flakes
-            accept-flake-config = true
-
-      - name: Setup Nix cache
-        uses: DeterminateSystems/magic-nix-cache-action@main
-
       - name: Build configuration
         run: |
           echo "Building configuration for ${{ matrix.config }}"
@@ -91,7 +61,7 @@ jobs:
 
   build-artifacts:
     name: Build Artifacts
-    runs-on: ubuntu-latest
+    runs-on: [self-hosted, nix-builder]
     strategy:
       matrix:
         artifact:
@@ -102,16 +72,6 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v4
 
-      - name: Install Nix
-        uses: DeterminateSystems/nix-installer-action@main
-        with:
-          extra-conf: |
-            experimental-features = nix-command flakes
-            accept-flake-config = true
-
-      - name: Setup Nix cache
-        uses: DeterminateSystems/magic-nix-cache-action@main
-
       - name: Build artifact
         run: |
           echo "Building artifact ${{ matrix.artifact }}"

docs/DEVELOPMENT.md

@@ -66,7 +66,7 @@ sudo nixos-rebuild build --flake .
 
 ## Continuous Integration
 
-The repository uses GitHub Actions for automated testing and validation.
+The repository uses GitHub Actions for automated testing and validation. CI jobs run on the self-hosted `nix-builder` machine via SSH.
 
 ### CI Workflow
 
@@ -116,9 +116,14 @@ nix build .#nixosConfigurations.nix-builder.config.system.build.toplevel
 nix build .#lxc-nix-builder
 ```
 
-### CI Caching
+### Self-Hosted Runner
 
-The CI workflow uses [Magic Nix Cache](https://github.com/DeterminateSystems/magic-nix-cache-action) to speed up builds by caching Nix store paths between runs. This significantly reduces build times for repeated builds.
+CI jobs run on the `nix-builder` host as a self-hosted GitHub Actions runner. This provides:
+
+- Native Nix environment without installation overhead
+- Access to local Nix store for faster builds
+- Consistent build environment matching deployment targets
+- Direct access to build caching infrastructure
 
 ### Troubleshooting CI Failures