Expose native storage retention for VM and CT backups

.github/scripts/tests/test_command_descriptions.py

@@ -200,6 +200,10 @@ class CommandDescriptionsTests(unittest.TestCase):
                 if lang != "en":
                     messages = json.loads(path.read_text())
                     english = catalog("en")
+                    # Storage-retention labels await the translation bot. Seed
+                    # only those new leaves in this steady-state fixture.
+                    for key, value in english["backup"]["storageRetention"].items():
+                        messages["backup"].setdefault("storageRetention", {}).setdefault(key, value)
                     for section, key in (("encryption", "pbsHelp"),
                                          ("keyfileActions", "pveKeyDescription")):
                         messages["backup"][section].setdefault(key, english["backup"][section][key])

.github/scripts/tests/test_vm_backup_jobs_wiring.py

@@ -15,7 +15,7 @@ class VmBackupJobsWiring(TestCase):
         source = ROUTES.read_text()
         routes = re.findall(r'@vm_backup_bp\.route\("([^"]+)", methods=\["(\w+)"\]\)\n@(\w+)\ndef (\w+)', source)
         self.assertEqual(len(routes), source.count('@vm_backup_bp.route('))
-        self.assertEqual(len(routes), 8)
+        self.assertEqual(len(routes), 10)
         for path, method, guard, name in routes:
             expected = 'require_auth' if method == 'GET' else 'require_admin_scope'
             self.assertEqual(guard, expected, f'{method} {path} ({name})')

.github/workflows/test-backup-storage-retention.yml

@@ -0,0 +1,50 @@
+name: Backup storage retention
+
+on:
+  pull_request:
+    paths:
+      - '.github/workflows/test-backup-storage-retention.yml'
+      - 'AppImage/scripts/flask_vm_backup_routes.py'
+      - 'AppImage/components/backup-storage-retention.tsx'
+      - 'AppImage/components/backup-tab.tsx'
+      - 'AppImage/components/vm-backup-jobs.tsx'
+      - 'AppImage/lib/backup-retention.ts'
+      - 'tests/test_vm_backup_jobs_api.py'
+      - 'tests/test_backup_storage_retention.cjs'
+  push:
+    branches: [main, develop]
+    paths:
+      - 'AppImage/scripts/flask_vm_backup_routes.py'
+      - 'AppImage/components/backup-storage-retention.tsx'
+      - 'AppImage/lib/backup-retention.ts'
+      - 'tests/test_vm_backup_jobs_api.py'
+      - 'tests/test_backup_storage_retention.cjs'
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  storage-retention:
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          persist-credentials: false
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.11'
+      - uses: actions/setup-node@v6
+        with:
+          node-version: '22.14.0'
+      - name: Install fixture dependencies
+        run: |
+          python -m pip install 'Flask==3.1.2'
+          npm ci --prefix .github/ci/offline-node --ignore-scripts --no-audit --no-fund
+      - name: Test native job and storage configuration APIs
+        run: python -B -m unittest discover -s tests -p test_vm_backup_jobs_api.py -v
+      - name: Test shared retention properties
+        env:
+          NODE_PATH: ${{ github.workspace }}/.github/ci/offline-node/node_modules
+        run: node tests/test_backup_storage_retention.cjs

AppImage/components/backup-storage-retention.tsx

@@ -0,0 +1,99 @@
+"use client"
+
+import { useState } from "react"
+import useSWR from "swr"
+import { HardDrive, Loader2, Pencil, RefreshCw } from "lucide-react"
+import { Card, CardContent, CardHeader, CardTitle } from "./ui/card"
+import { Badge } from "./ui/badge"
+import { Button } from "./ui/button"
+import { Checkbox } from "./ui/checkbox"
+import { Dialog, DialogContent, DialogDescription, DialogFooter, DialogHeader, DialogTitle } from "./ui/dialog"
+import { Input } from "./ui/input"
+import { Label } from "./ui/label"
+import { fetchApi } from "../lib/api-config"
+import { buildRetention, parseRetention, RETENTION } from "../lib/backup-retention"
+import { useT } from "../lib/i18n/provider"
+
+interface StorageRetention { id: string; type: string; prune_backups: string; digest: string }
+const fetcher = (url: string) => fetchApi<{ storages: StorageRetention[] }>(url)
+
+export function BackupStorageRetention() {
+  const t = useT()
+  const { data, error, mutate, isValidating } = useSWR("/api/vm-backup-storages", fetcher)
+  const [editing, setEditing] = useState<StorageRetention | null>(null)
+  const [fields, setFields] = useState<Record<string, string>>({})
+  const [keepAll, setKeepAll] = useState(false)
+  const [busy, setBusy] = useState(false)
+  const [message, setMessage] = useState("")
+  const [saveError, setSaveError] = useState("")
+
+  function edit(storage: StorageRetention) {
+    const policy = parseRetention(storage.prune_backups)
+    setFields(policy.fields)
+    setKeepAll(policy.keepAll || !storage.prune_backups)
+    setSaveError("")
+    setMessage("")
+    setEditing(storage)
+  }
+
+  async function save() {
+    if (!editing || busy) return
+    const prune = buildRetention(fields, keepAll)
+    if (!prune) return setSaveError(t("backup.storageRetention.choosePolicy"))
+    setBusy(true)
+    setSaveError("")
+    try {
+      await fetchApi(`/api/vm-backup-storages/${encodeURIComponent(editing.id)}`, {
+        method: "PUT", body: JSON.stringify({ digest: editing.digest, prune_backups: prune }),
+      })
+      setMessage(t("backup.storageRetention.saved"))
+      setEditing(null)
+      await mutate()
+    } catch (error) {
+      setSaveError(`${t("backup.storageRetention.saveFailed")} ${error instanceof Error ? error.message : ""}`)
+    } finally { setBusy(false) }
+  }
+
+  return <Card className="border-border bg-card/50">
+    <CardHeader className="pb-3 flex-row items-center justify-between gap-2">
+      <CardTitle className="text-base flex items-center gap-2"><HardDrive className="h-4 w-4" />{t("backup.storageRetention.title")}</CardTitle>
+      <Button variant="ghost" size="sm" disabled={isValidating} onClick={() => { void mutate().catch(() => {}) }}>
+        <RefreshCw className={`h-4 w-4 mr-2 ${isValidating ? "animate-spin" : ""}`} />{t("backup.storageRetention.refresh")}
+      </Button>
+    </CardHeader>
+    <CardContent className="space-y-3">
+      <p className="text-xs text-muted-foreground">{t("backup.storageRetention.description")}</p>
+      {message && <p role="status" className="text-xs text-emerald-500">{message}</p>}
+      {error ? <p role="alert" className="text-xs text-destructive">{t("backup.storageRetention.loadFailed")}</p> : !data ?
+        <Loader2 className="h-4 w-4 animate-spin" /> : !data.storages.length ?
+        <p className="text-xs text-muted-foreground">{t("backup.storageRetention.empty")}</p> :
+        data.storages.map(storage => <div key={storage.id} className="flex flex-wrap gap-2 items-center border rounded-lg p-3">
+          <span className="font-medium text-sm">{storage.id}</span><Badge variant="outline">{storage.type}</Badge>
+          <span className="text-xs font-mono text-muted-foreground break-all">{storage.prune_backups || t("backup.storageRetention.default")}</span>
+          <Button variant="outline" size="sm" className="ml-auto gap-1" onClick={() => edit(storage)} disabled={!storage.digest || busy}>
+            <Pencil className="h-3 w-3" />{t("backup.storageRetention.edit")}
+          </Button>
+        </div>)}
+    </CardContent>
+    <Dialog open={!!editing} onOpenChange={open => { if (!open && !busy) setEditing(null) }}>
+      <DialogContent className="bg-accent [&_input]:bg-background">
+        <DialogHeader><DialogTitle>{t("backup.storageRetention.editTitle", { storage: editing?.id ?? "" })}</DialogTitle>
+          <DialogDescription>{t("backup.storageRetention.effect")}</DialogDescription></DialogHeader>
+        <Label className="flex items-center gap-2"><Checkbox checked={keepAll} disabled={busy} onCheckedChange={checked => {
+          setKeepAll(checked === true)
+          if (checked) setFields({})
+        }} />{t("backup.storageRetention.keepAll")}</Label>
+        <div className="grid grid-cols-2 gap-3">
+          {RETENTION.map(key => <div key={key} className="space-y-1">
+            <Label htmlFor={`storage-retention-${key}`}>{t(`backup.retention.${key}`)}</Label>
+            <Input id={`storage-retention-${key}`} type="number" min={1} max={99999} step={1} disabled={keepAll || busy}
+              value={fields[key] ?? ""} onChange={event => setFields(previous => ({ ...previous, [key]: event.target.value }))} />
+          </div>)}
+        </div>
+        {saveError && <p role="alert" className="text-xs text-destructive break-words">{saveError}</p>}
+        <DialogFooter><Button variant="outline" disabled={busy} onClick={() => setEditing(null)}>{t("backup.storageRetention.cancel")}</Button>
+          <Button disabled={busy} onClick={save}>{busy && <Loader2 className="h-4 w-4 mr-2 animate-spin" />}{t("backup.storageRetention.save")}</Button></DialogFooter>
+      </DialogContent>
+    </Dialog>
+  </Card>
+}

AppImage/components/backup-tab.tsx

@@ -7,6 +7,7 @@ import { useState } from "react"
 import { DatabaseBackup } from "lucide-react"
 import { HostBackup } from "./host-backup"
 import { VmBackupJobs } from "./vm-backup-jobs"
+import { BackupStorageRetention } from "./backup-storage-retention"
 import { useT } from "../lib/i18n/provider"
 
 type BackupView = "host" | "guests"
@@ -51,7 +52,7 @@ export function BackupTab() {
       <div className={view === "host" ? "" : "hidden"}>
         <HostBackup />
       </div>
-      {view === "guests" && <VmBackupJobs />}
+      {view === "guests" && <><VmBackupJobs /><BackupStorageRetention /></>}
     </div>
   )
 }

AppImage/components/vm-backup-jobs.tsx

@@ -21,6 +21,7 @@ import {
 import { fetchApi } from "../lib/api-config"
 import { cancelButtonClass } from "../lib/utils"
 import { useT } from "../lib/i18n/provider"
+import { RETENTION, parseRetention, buildRetention } from "../lib/backup-retention"
 
 interface VmBackupJob {
   id: string
@@ -70,24 +71,6 @@ const EMPTY_FORM: FormState = {
   mode: "snapshot", compress: "zstd", retention: {}, keepAll: false, notes: "{{guestname}}", attached: [],
 }
 
-// The limits a job can keep, in the order Proxmox lists them.
-const RETENTION = ["last", "hourly", "daily", "weekly", "monthly", "yearly"] as const
-
-const parseRetention = (prune: string) => {
-  const fields: Record<string, string> = {}
-  let keepAll = false
-  for (const part of prune.split(",")) {
-    const [key, value] = part.trim().split("=")
-    if (key === "keep-all") keepAll = value === "1"
-    else if (key?.startsWith("keep-") && Number(value) > 0) fields[key.slice(5)] = String(Number(value))
-  }
-  return { fields, keepAll }
-}
-
-const buildRetention = (fields: Record<string, string>, keepAll: boolean) => {
-  const parts = RETENTION.filter((key) => Number(fields[key]) > 0).map((key) => `keep-${key}=${Number(fields[key])}`)
-  return parts.length ? parts.join(",") : keepAll ? "keep-all=1" : ""
-}
 
 const isOn = (value: unknown) => value === 1 || value === true || value === "1"
 const jobEnabled = (job: VmBackupJob) => job.enabled === undefined || isOn(job.enabled)

AppImage/lib/backup-retention.ts

@@ -0,0 +1,18 @@
+// Native Proxmox retention properties, shared by storage and job editors.
+export const RETENTION = ["last", "hourly", "daily", "weekly", "monthly", "yearly"] as const
+
+export function parseRetention(prune: string) {
+  const fields: Record<string, string> = {}
+  let keepAll = false
+  for (const part of prune.split(",")) {
+    const [key, value] = part.trim().split("=")
+    if (key === "keep-all") keepAll = value === "1"
+    else if (key?.startsWith("keep-") && Number(value) > 0) fields[key.slice(5)] = String(Number(value))
+  }
+  return { fields, keepAll }
+}
+
+export function buildRetention(fields: Record<string, string>, keepAll: boolean) {
+  const parts = RETENTION.filter(key => Number(fields[key]) > 0).map(key => `keep-${key}=${Number(fields[key])}`)
+  return parts.length ? parts.join(",") : keepAll ? "keep-all=1" : ""
+}

AppImage/messages/en/common.json

@@ -3938,6 +3938,23 @@
     }
   },
   "backup": {
+    "storageRetention": {
+      "title": "Storage retention",
+      "keepAll": "Keep all backups",
+      "description": "Default backup retention stored in Proxmox. Backup jobs with an explicit policy override this default.",
+      "refresh": "Refresh",
+      "saved": "Storage retention saved. No pruning was run.",
+      "choosePolicy": "Choose Keep all or at least one positive retention count.",
+      "saveFailed": "Could not save storage retention. Refresh the list if the configuration changed.",
+      "loadFailed": "Could not load storage retention.",
+      "empty": "No backup storages found.",
+      "default": "Proxmox default",
+      "edit": "Edit",
+      "editTitle": "Retention for {storage}",
+      "effect": "Applies to future backup runs that inherit this storage policy. Saving does not delete existing backups. Protected backups remain protected.",
+      "cancel": "Cancel",
+      "save": "Save retention"
+    },
     "actions": {
       "addAnother": "Add another",
       "addPath": "Add path",

AppImage/scripts/flask_vm_backup_routes.py

@@ -16,6 +16,9 @@ Endpoints, all under /api/vm-backup-jobs:
   DELETE /<id>             delete a job (its backups are kept)
   POST   /<id>/toggle      enable / disable
   POST   /<id>/run         run it now, as a Proxmox task on each node
+
+Storage retention is read/edited under /api/vm-backup-storages. Saving a
+policy only changes the native storage configuration; it never runs pruning.
 """
 
 import json
@@ -229,6 +232,56 @@ def options():
     })
 
 
+@vm_backup_bp.route("/api/vm-backup-storages", methods=["GET"])
+@require_auth
+def backup_storage_retention():
+    ok, storages = _pvesh_json(["get", "/storage"])
+    if not ok or not isinstance(storages, list):
+        return _err(storages if not ok else "Invalid storage inventory", 502)
+    return jsonify({"storages": [
+        {"id": storage["storage"], "type": storage.get("type", ""),
+         "prune_backups": _flat(storage.get("prune-backups") or ""),
+         "digest": storage.get("digest", "")}
+        for storage in storages
+        if isinstance(storage, dict) and storage.get("storage")
+        and "backup" in (storage.get("content") or "").split(",")
+    ]})
+
+
+@vm_backup_bp.route("/api/vm-backup-storages/<storage_id>", methods=["PUT"])
+@require_admin_scope
+def update_backup_storage_retention(storage_id):
+    if not STORAGE_RE.fullmatch(storage_id):
+        return _err("Invalid storage")
+    data = request.get_json(silent=True)
+    if not isinstance(data, dict):
+        return _err("A retention policy and current configuration digest are required")
+    digest, prune = data.get("digest"), data.get("prune_backups")
+    if not isinstance(digest, str) or not re.fullmatch(r"[a-fA-F0-9]{40}", digest):
+        return _err("Refresh the storage list before editing its retention")
+    if not isinstance(prune, str) or not PRUNE_RE.fullmatch(prune):
+        return _err("Invalid retention policy")
+    pairs = [part.split("=", 1) for part in prune.split(",")]
+    keys = [key for key, _ in pairs]
+    if (len(keys) != len(set(keys)) or
+            ("keep-all" in keys and (len(keys) != 1 or pairs[0][1] != "1")) or
+            not any(int(value) > 0 for _, value in pairs)):
+        return _err("Choose keep-all=1 or one or more positive retention counts")
+    # Check that this is still a backup storage, then let Proxmox check the
+    # digest under its storage lock. Other storage settings are never passed.
+    ok, storage = _pvesh_json(["get", f"/storage/{storage_id}"])
+    if not ok:
+        return _err(storage, 502)
+    if not isinstance(storage, dict) or "backup" not in (storage.get("content") or "").split(","):
+        return _err("This storage does not accept backups", 409)
+    if storage.get("digest") != digest:
+        return _err("Storage configuration changed; refresh before saving", 409)
+    ok, out = _pvesh(["set", f"/storage/{storage_id}", "--digest", digest, "--prune-backups", prune])
+    if not ok:
+        return _err(out, 409)
+    return jsonify({"success": True})
+
+
 @vm_backup_bp.route("/api/vm-backup-jobs", methods=["POST"])
 @require_admin_scope
 def create_job():

tests/test_backup_storage_retention.cjs

@@ -0,0 +1,27 @@
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const vm = require('node:vm');
+const ts = require('typescript');
+const source = fs.readFileSync('AppImage/lib/backup-retention.ts', 'utf8');
+const context = { exports: {} };
+vm.runInNewContext(ts.transpileModule(source, { compilerOptions: { module: ts.ModuleKind.CommonJS } }).outputText, context);
+const { parseRetention, buildRetention } = context.exports;
+for (const policy of ['keep-all=1', 'keep-last=3', 'keep-last=3,keep-weekly=2', 'keep-hourly=24,keep-daily=7,keep-monthly=12,keep-yearly=2']) {
+  const { fields, keepAll } = parseRetention(policy);
+  assert.equal(buildRetention(fields, keepAll), policy);
+}
+assert.equal(buildRetention({}, false), '', 'empty policy remains explicit');
+assert.equal(buildRetention({}, true), 'keep-all=1');
+assert.equal(buildRetention({ daily: '3', hourly: '0', last: '' }, false), 'keep-daily=3');
+assert.equal(buildRetention({ last: '3' }, true), 'keep-last=3', 'existing job editor precedence preserved');
+const component = fs.readFileSync('AppImage/components/backup-storage-retention.tsx', 'utf8');
+const english = JSON.parse(fs.readFileSync('AppImage/messages/en/common.json')).backup.storageRetention;
+for (const [, key] of component.matchAll(/t\("backup\.storageRetention\.([A-Za-z]+)"/g)) {
+  assert.ok(typeof english[key] === 'string' && english[key], `translation: ${key}`);
+}
+assert.ok(component.includes('digest: editing.digest'));
+assert.ok(component.includes('method: "PUT"'));
+assert.ok(!component.includes('/prune'));
+assert.ok(fs.readFileSync('AppImage/components/vm-backup-jobs.tsx', 'utf8').includes('from "../lib/backup-retention"'));
+assert.ok(fs.readFileSync('AppImage/components/backup-tab.tsx', 'utf8').includes('<BackupStorageRetention />'));
+console.log('PASS: shared native retention properties, keep-all/count round trips, explicit empty policy, translations and digest wiring');

tests/test_vm_backup_jobs_api.py

@@ -1,5 +1,6 @@
 """VM/CT backup jobs API: what reaches pvesh, with pvesh itself replaced."""
 import importlib
+import importlib.util
 import json
 import sys
 import types
@@ -23,6 +24,34 @@ GUESTS = [{"vmid": 100, "name": "web", "type": "qemu", "node": "pve1"},
           {"vmid": 200, "name": "other", "type": "qemu", "node": "pve2"}]
 
 
+@unittest.skipIf(Flask is None, "Flask runtime required")
+class StorageRetentionAuthorizationTests(unittest.TestCase):
+    def test_real_authentication_guard_blocks_read_only_writes_before_pvesh(self):
+        scripts = Path(__file__).resolve().parents[1] / "AppImage/scripts"
+        auth = types.ModuleType("auth_manager")
+        auth.load_auth_config = lambda: {"enabled": True}
+        auth.verify_token = lambda token: "tester" if token in ("admin", "reader") else None
+        auth.verify_token_full = lambda token: ("tester", "full_admin" if token == "admin" else "read_only")
+        spec = importlib.util.spec_from_file_location("storage_retention_middleware", scripts / "jwt_middleware.py")
+        middleware = importlib.util.module_from_spec(spec)
+        with patch.dict(sys.modules, auth_manager=auth):
+            spec.loader.exec_module(middleware)
+        spec = importlib.util.spec_from_file_location("storage_retention_auth_routes", scripts / "flask_vm_backup_routes.py")
+        routes = importlib.util.module_from_spec(spec)
+        with patch.dict(sys.modules, jwt_middleware=middleware):
+            spec.loader.exec_module(routes)
+        app = Flask(__name__)
+        app.register_blueprint(routes.vm_backup_bp)
+        client = app.test_client()
+        data = {"digest": "a" * 40, "prune_backups": "keep-last=3"}
+        with patch.object(routes, "_pvesh") as run:
+            self.assertEqual(client.get("/api/vm-backup-storages").status_code, 401)
+            self.assertEqual(client.put("/api/vm-backup-storages/local", json=data).status_code, 401)
+            self.assertEqual(client.put("/api/vm-backup-storages/local", json=data,
+                                        headers={"Authorization": "Bearer reader"}).status_code, 403)
+        run.assert_not_called()
+
+
 @unittest.skipIf(Flask is None, "Flask runtime required")
 class VmBackupJobsApiTests(unittest.TestCase):
     def setUp(self):
@@ -73,9 +102,59 @@ class VmBackupJobsApiTests(unittest.TestCase):
 
     def test_reading_needs_a_session_and_changing_needs_an_administrator(self):
         guards = dict((name, kind) for kind, name in self.guards)
-        self.assertEqual({name for name, kind in guards.items() if kind == "auth"}, {"list_jobs", "options", "get_job"})
+        self.assertEqual({name for name, kind in guards.items() if kind == "auth"}, {"list_jobs", "options", "get_job", "backup_storage_retention"})
         self.assertEqual({name for name, kind in guards.items() if kind == "admin"},
-                         {"create_job", "update_job", "delete_job", "toggle_job", "run_job"})
+                         {"create_job", "update_job", "delete_job", "toggle_job", "run_job", "update_backup_storage_retention"})
+
+    def test_storage_retention_lists_only_backup_storages_and_no_secrets(self):
+        with patch.object(self.routes, "_pvesh_json", return_value=(True, [
+            {"storage": "local", "type": "dir", "content": "backup,iso", "digest": "a" * 40,
+             "prune-backups": {"keep-last": 3}, "password": "private"},
+            {"storage": "images", "type": "dir", "content": "images", "digest": "a" * 40},
+        ])):
+            answer = self.client.get("/api/vm-backup-storages").get_json()
+        self.assertEqual(answer, {"storages": [{"id": "local", "type": "dir", "digest": "a" * 40, "prune_backups": "keep-last=3"}]})
+
+    def storage_policy(self, prune="keep-last=3,keep-weekly=2", digest="a" * 40, current=None):
+        if current is None:
+            current = {"storage": "local", "content": "backup,iso", "digest": "a" * 40}
+        with patch.object(self.routes, "_pvesh_json", return_value=(True, current)), self.pvesh():
+            return self.client.put("/api/vm-backup-storages/local", json={"digest": digest, "prune_backups": prune})
+
+    def test_saving_native_storage_retention_never_runs_pruning_or_changes_other_properties(self):
+        response = self.storage_policy()
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(self.changes(), [["set", "/storage/local", "--digest", "a" * 40,
+                                          "--prune-backups", "keep-last=3,keep-weekly=2"]])
+        self.calls.clear()
+        self.assertEqual(self.storage_policy("keep-all=1").status_code, 200)
+        self.assertEqual(self.changes()[0][-1], "keep-all=1")
+
+    def test_invalid_storage_retention_is_rejected_before_commands(self):
+        invalid = [None, [], {}, {"digest": "a" * 40, "prune_backups": []}]
+        for prune in ("", "keep-last=-1", "keep-all=0", "keep-all=2", "keep-last=0", "keep-last=1,keep-last=2",
+                      "keep-all=1,keep-last=2", "keep-last=2 --delete path", "keep-last=1\n", "keep-other=1"):
+            invalid.append({"digest": "a" * 40, "prune_backups": prune})
+        invalid += [{"digest": "invalid", "prune_backups": "keep-last=1"}]
+        with patch.object(self.routes, "_pvesh") as run:
+            for data in invalid:
+                with self.subTest(data=data):
+                    self.assertEqual(self.client.put("/api/vm-backup-storages/local", json=data).status_code, 400)
+            self.assertEqual(self.client.put("/api/vm-backup-storages/-bad", json=invalid[-1]).status_code, 400)
+        run.assert_not_called()
+
+    def test_stale_storage_configuration_or_non_backup_storage_is_not_overwritten(self):
+        for current in ({"content": "backup", "digest": "b" * 40},
+                        {"content": "images", "digest": "a" * 40}):
+            self.assertEqual(self.storage_policy(current=current).status_code, 409)
+        self.assertEqual(self.changes(), [])
+
+    def test_native_storage_update_failure_is_visible(self):
+        with patch.object(self.routes, "_pvesh_json", return_value=(True, {"content": "backup", "digest": "a" * 40})), \
+                patch.object(self.routes, "_pvesh", return_value=(False, "configuration changed under lock")):
+            response = self.client.put("/api/vm-backup-storages/local", json={"digest": "a" * 40, "prune_backups": "keep-last=3"})
+        self.assertEqual(response.status_code, 409)
+        self.assertIn("changed", response.get_json()["error"])
 
     def test_the_list_gives_text_properties_and_the_host_backups_that_hang_from_a_job(self):
         with self.pvesh(), patch.object(self.routes, "_host_backups_attached",