Run KVM validation on self-hosted runners

.github/workflows/kvm-publishable.yml

@@ -5,19 +5,38 @@ on:
 
 jobs:
   publishable-kvm-suite:
-    runs-on: ubuntu-latest
+    runs-on:
+      - self-hosted
+      - linux
+      - x64
     timeout-minutes: 360
 
     steps:
       - uses: actions/checkout@v4
 
-      - uses: DeterminateSystems/nix-installer-action@v11
-
-      - uses: DeterminateSystems/magic-nix-cache-action@v8
+      - name: Ensure Nix Is Available
+        run: |
+          set -euo pipefail
+          if ! command -v nix >/dev/null 2>&1; then
+            curl -L https://nixos.org/nix/install | sh -s -- --no-daemon
+          fi
+          if [[ -f /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh ]]; then
+            . /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh
+          elif [[ -f "$HOME/.nix-profile/etc/profile.d/nix.sh" ]]; then
+            . "$HOME/.nix-profile/etc/profile.d/nix.sh"
+          fi
+          mkdir -p "$HOME/.config/nix"
+          printf '%s\n' 'experimental-features = nix-command flakes' > "$HOME/.config/nix/nix.conf"
+          nix --version
 
       - name: Probe KVM Environment
         run: |
           set -euo pipefail
+          if [[ -f /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh ]]; then
+            . /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh
+          elif [[ -f "$HOME/.nix-profile/etc/profile.d/nix.sh" ]]; then
+            . "$HOME/.nix-profile/etc/profile.d/nix.sh"
+          fi
           echo "hostname=$(hostname)"
           uname -a
           id
@@ -33,5 +52,10 @@ jobs:
       - name: Run Publishable KVM Suite
         run: |
           set -euo pipefail
+          if [[ -f /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh ]]; then
+            . /nix/var/nix/profiles/default/etc/profile.d/nix-daemon.sh
+          elif [[ -f "$HOME/.nix-profile/etc/profile.d/nix.sh" ]]; then
+            . "$HOME/.nix-profile/etc/profile.d/nix.sh"
+          fi
           chmod +x ./nix/test-cluster/run-publishable-kvm-suite.sh
           ./nix/test-cluster/run-publishable-kvm-suite.sh "$RUNNER_TEMP/publishable-kvm-suite"