feat: add coredns (#6)

We had some inconsistencies with node configuration and dns hickups.
This feature moves the coredns config into our software versioning system.

Reviewed-on: #6
Co-authored-by: Timo Behrendt <t.behrendt@t00n.de>
Co-committed-by: Timo Behrendt <t.behrendt@t00n.de>

.gitea/workflows/validate.yaml

@@ -18,3 +18,16 @@ jobs:
       - name: Validate
         run: |
           kubectl apply --server-side --field-manager=t000-n --dry-run=server -f node-labels
+
+  validate-coredns:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v5
+      - uses: azure/setup-kubectl@v4
+      - uses: azure/k8s-set-context@v4
+        with:
+          method: kubeconfig
+          kubeconfig: ${{ secrets.KUBECONFIG }}
+      - name: Validate
+        run: |
+          kubectl apply -n kube-system -f coredns