fix(backup): worker-safe paths and python WebDAV upload fallback

Default cache to /tmp when HOME is unwritable; allow python3 upload when
curl is absent (activity-core worker image).

lib/railiance-backup-common.sh

@@ -38,16 +38,41 @@ railiance_backup_require_tools() {
     export PATH="$(dirname "${RAILIANCE_BACKUP_AGE_BIN}"):${PATH}"
   fi
   local t
-  for t in age curl kubectl; do
+  for t in age kubectl; do
     command -v "$t" >/dev/null 2>&1 || { echo "ERROR: missing required tool: $t (run tools/cmd/install-cnpg-backup-vendor-tools)" >&2; exit 1; }
   done
+  # curl optional — upload falls back to python3 urllib (activity-core worker has no curl)
+  if ! command -v curl >/dev/null 2>&1 && ! command -v python3 >/dev/null 2>&1; then
+    echo "ERROR: need curl or python3 for Nextcloud upload" >&2
+    exit 1
+  fi
 }
 
 railiance_backup_nc_upload() {
   local file="$1" remote_name="$2"
-  local dest="${RAILIANCE_BACKUP_NC_WEBDAV_URL}/${RAILIANCE_BACKUP_NC_PREFIX}/${remote_name}"
+  local dest="${RAILIANCE_BACKUP_NC_WEBDAV_URL%/}/${RAILIANCE_BACKUP_NC_PREFIX}/${remote_name}"
-  curl -sf -u "${RAILIANCE_BACKUP_NC_TOKEN}:" -T "$file" "$dest" \
+  if command -v curl >/dev/null 2>&1; then
-    || { echo "ERROR: Nextcloud upload failed: ${remote_name}" >&2; return 1; }
+    curl -sf -u "${RAILIANCE_BACKUP_NC_TOKEN}:" -T "$file" "$dest" \
+      || { echo "ERROR: Nextcloud upload failed: ${remote_name}" >&2; return 1; }
+    return 0
+  fi
+  # Python fallback (worker image)
+  RAILIANCE_BACKUP_NC_TOKEN="${RAILIANCE_BACKUP_NC_TOKEN}" \
+  RAILIANCE_BACKUP_UPLOAD_URL="${dest}" \
+  RAILIANCE_BACKUP_UPLOAD_FILE="${file}" \
+  python3 - <<'PY' || { echo "ERROR: Nextcloud upload failed: ${remote_name}" >&2; return 1; }
+import os, urllib.request, base64
+url = os.environ["RAILIANCE_BACKUP_UPLOAD_URL"]
+path = os.environ["RAILIANCE_BACKUP_UPLOAD_FILE"]
+token = os.environ["RAILIANCE_BACKUP_NC_TOKEN"]
+data = open(path, "rb").read()
+req = urllib.request.Request(url, data=data, method="PUT")
+req.add_header("Authorization", "Basic " + base64.b64encode(f"{token}:".encode()).decode())
+req.add_header("Content-Type", "application/octet-stream")
+with urllib.request.urlopen(req, timeout=600) as resp:
+    if resp.status not in (200, 201, 204):
+        raise SystemExit(f"HTTP {resp.status}")
+PY
 }
 
 railiance_backup_encrypt() {

tools/cmd/cnpg-option-a-backup

@@ -28,7 +28,16 @@ source "${ROOT}/lib/railiance-backup-common.sh"
 DRY_RUN="${RAILIANCE_BACKUP_DRY_RUN:-0}"
 UPDATE_STATUS="${CNPG_UPDATE_STATUS_CM:-1}"
 STATUS_CM="${CNPG_OPTION_A_STATUS_CM:-cnpg-option-a-status}"
-BACKUP_ROOT="${BACKUP_DIR:-${XDG_CACHE_HOME:-$HOME/.cache}/railiance/backups/cnpg}"
+# Prefer explicit BACKUP_DIR; fall back to cache, then /tmp (worker pods often lack $HOME).
+if [[ -n "${BACKUP_DIR:-}" ]]; then
+  BACKUP_ROOT="${BACKUP_DIR}"
+elif [[ -n "${XDG_CACHE_HOME:-}" ]]; then
+  BACKUP_ROOT="${XDG_CACHE_HOME}/railiance/backups/cnpg"
+elif [[ -n "${HOME:-}" && -w "${HOME}" ]]; then
+  BACKUP_ROOT="${HOME}/.cache/railiance/backups/cnpg"
+else
+  BACKUP_ROOT="/tmp/railiance-backups/cnpg"
+fi
 JSON_ONLY="${CNPG_BACKUP_JSON:-1}"
 
 KUBECONFIG_CORE="${KUBECONFIG_CORE:-${KUBECONFIG_COULOMBCORE:-$HOME/.kube/config}}"