ci: new workflow

.gitea/workflows/runner-nix-smoke.yaml

@@ -16,6 +16,9 @@ jobs:
     name: nix label smoke
     runs-on: nix
     steps:
+      - name: Checkout repository
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af6832  # v4.2.2
+
       - name: Nix version and cache configuration
         run: |
           set -eu

docs/README.md

@@ -6,8 +6,8 @@
 
 Common labels for zero-idle runners:
 
-- `ubuntu-latest` — default Ubuntu-style smoke / host runner path
+- `ubuntu-latest` — persistent Ubuntu 24.04 `cx23` worker
-- `nix` — Nix-capable runner path
+- `nix` — persistent Nix-capable Ubuntu `cx23` worker
 - `gross-x86` — x86 fallback chain `cx53` / `cx43` / `cx33`
 - `gross-arm` — ARM fallback chain `cax41` / `cax31` / `cax21`
 - `gross-x86-perf` — x86 performance chain `cx53` / `cpx62` / `cpx52`
@@ -19,5 +19,8 @@ Common labels for zero-idle runners:
 
 Region order for fallback: `nbg1`, then `fsn1`, then `hel1`.
 
+`nix` and `ubuntu-latest` are persistent workers; only `gross-*` labels use
+zero-idle ephemeral VMs.
+
 Operational details: `infra/gitea-runners/runbook.md` and
 `package/gitea-runner-controller/decide.sh`.

nixos/module/hectic/service/gitea-runner-controller.nix

@@ -54,7 +54,9 @@ let
       "GCR_ACT_RUNNER_SHA256=${cfg.actRunnerSha256}"
     ]
     ++ lib.optionals (cfg.imageId != null) [ "GCR_IMAGE_ID=${cfg.imageId}" ]
-    ++ lib.optionals (cfg.armImageId != null) [ "GCR_ARM_IMAGE_ID=${cfg.armImageId}" ];
+    ++ lib.optionals (cfg.armImageId != null) [ "GCR_ARM_IMAGE_ID=${cfg.armImageId}" ]
+    ++ lib.optionals (cfg.nixImageId != null) [ "GCR_NIX_IMAGE_ID=${cfg.nixImageId}" ]
+    ++ lib.optionals (cfg.armNixImageId != null) [ "GCR_ARM_NIX_IMAGE_ID=${cfg.armNixImageId}" ];
 in
 {
   options = {
@@ -129,6 +131,18 @@ in
           whose fallback chain includes ARM server types.
         '';
       };
+      nixImageId = lib.mkOption {
+        type = with lib.types; nullOr str;
+        default = null;
+        example = "161547269";
+        description = "Hetzner Ubuntu image id used by Nix-capable x86 runners.";
+      };
+      armNixImageId = lib.mkOption {
+        type = with lib.types; nullOr str;
+        default = null;
+        example = "161547270";
+        description = "Hetzner Ubuntu image id used by Nix-capable ARM runners.";
+      };
       actRunnerVersion = lib.mkOption {
         type = lib.types.str;
         default = "1.0.6";

nixos/system/hectic-lab/hectic-lab.nix

@@ -111,6 +111,8 @@ in {
       enable  = true;
       imageId = "424558114"; # MicroOS x86 + Hetzner datasource dhcpcd fix
       armImageId = "423979717"; # OpenSUSE MicroOS ARM K3S 2026-08-24 snapshot
+      nixImageId = "161547269"; # Ubuntu 24.04 x86; Nix needs writable root
+      armNixImageId = "161547270"; # Ubuntu 24.04 ARM; Nix needs writable root
       allowedRepos = [
         "hinterland/*"
         "yukkop/*"

package/gitea-runner-controller/decide.sh

@@ -22,8 +22,6 @@ gcr_server_hourly_rate() {
 
 gcr_label_ttl() {
     case "$1" in
-        ubuntu-latest)   printf '60'  ;;
-        nix)             printf '180' ;;
         gross-x86)       printf '180' ;;
         gross-arm)       printf '180' ;;
         gross-x86-perf)  printf '180' ;;
@@ -40,12 +38,6 @@ gcr_label_ttl() {
 gcr_label_candidates() {
     label="$1"
     case "$label" in
-        ubuntu-latest)
-            printf '%s\n' 'cx33 nbg1 amd64' 'cx33 fsn1 amd64' 'cx33 hel1 amd64'
-            ;;
-        nix)
-            printf '%s\n' 'cx33 nbg1 amd64' 'cx33 fsn1 amd64' 'cx33 hel1 amd64'
-            ;;
         gross-x86)
             printf '%s\n' \
                 'cx53 nbg1 amd64' 'cx53 fsn1 amd64' 'cx53 hel1 amd64' \

package/gitea-runner-controller/hcloud.sh

@@ -8,9 +8,14 @@
 GCR_API="https://api.hetzner.cloud/v1"
 
 gcr_image_id_for_arch() {
-    case "$1" in
+    arch="$1"; label="${2:-}"
-        amd64) [ -n "${GCR_IMAGE_ID:-}" ] && printf '%s' "$GCR_IMAGE_ID" ;;
+    nix_image=0
-        arm64) [ -n "${GCR_ARM_IMAGE_ID:-}" ] && printf '%s' "$GCR_ARM_IMAGE_ID" ;;
+    case "$label" in nix|gross-nix-*) nix_image=1 ;; esac
+    case "$arch:$nix_image" in
+        amd64:0) [ -n "${GCR_IMAGE_ID:-}" ] && printf '%s' "$GCR_IMAGE_ID" ;;
+        arm64:0) [ -n "${GCR_ARM_IMAGE_ID:-}" ] && printf '%s' "$GCR_ARM_IMAGE_ID" ;;
+        amd64:1) [ -n "${GCR_NIX_IMAGE_ID:-}" ] && printf '%s' "$GCR_NIX_IMAGE_ID" ;;
+        arm64:1) [ -n "${GCR_ARM_NIX_IMAGE_ID:-}" ] && printf '%s' "$GCR_ARM_NIX_IMAGE_ID" ;;
         *) return 1 ;;
     esac
 }
@@ -168,7 +173,7 @@ gcr_vm_create() {
     while read -r candidate_type candidate_loc candidate_arch; do
         [ -n "${candidate_type:-}" ] || continue
         candidate_n=$((candidate_n + 1))
-        image_id="$(gcr_image_id_for_arch "$candidate_arch")" || {
+        image_id="$(gcr_image_id_for_arch "$candidate_arch" "$label")" || {
             gcr_log warn --ns=hcloud "skip candidate[$candidate_n] label=$label arch=$candidate_arch no image"
             continue
         }