Storage limit: 80% warning and limit in the web interface

- after each successful backup the stored size is recorded; at 80% of a
  location's limit administrators get a notification (once a day)
- locations list shows stored size and limit; the add form has a
  'maximum size' field that explains that empty means unlimited and
  billed by the provider; PUT /api/targets/{id}/limit (password
  confirmation)

Tested on NC34 with the OVH test bucket: a backup above the limit stops,
a successful one at 81% sends the warning.

appinfo/info.xml

@@ -5,7 +5,7 @@
     <name>NG Backup</name>
     <summary>Encrypted, incremental backups of your Nextcloud with restore from the web interface</summary>
     <description><![CDATA[Work in progress, not ready for use.]]></description>
-    <version>0.0.17</version>
+    <version>0.0.18</version>
     <licence>agpl</licence>
     <author>Dillard Blom</author>
     <namespace>NgBackup</namespace>

appinfo/routes.php

@@ -20,6 +20,7 @@ return [
 		['name' => 'AdminApi#addTarget', 'url' => '/api/targets', 'verb' => 'POST'],
 		['name' => 'AdminApi#removeTarget', 'url' => '/api/targets/{id}', 'verb' => 'DELETE'],
 		['name' => 'AdminApi#testTarget', 'url' => '/api/targets/{id}/test', 'verb' => 'POST'],
+		['name' => 'AdminApi#setTargetLimit', 'url' => '/api/targets/{id}/limit', 'verb' => 'PUT'],
 		['name' => 'AdminApi#startBackup', 'url' => '/api/backups', 'verb' => 'POST'],
 		['name' => 'AdminApi#setSchedule', 'url' => '/api/schedule', 'verb' => 'PUT'],
 		['name' => 'AdminApi#snapshots', 'url' => '/api/targets/{targetId}/snapshots', 'verb' => 'GET'],

lib/Controller/AdminApiController.php

@@ -55,7 +55,8 @@ class AdminApiController extends Controller {
 		$targets = [];
 		foreach ($this->targets->list() as $t) {
 			$targets[] = ['id' => $t->getId(), 'name' => $t->getName(), 'backend' => $t->getBackend(), 'path' => $t->getBasePath(),
-				'repositoryId' => $t->getRepositoryId(), 'createdAt' => $t->getCreatedAt()];
+				'repositoryId' => $t->getRepositoryId(), 'createdAt' => $t->getCreatedAt(), 'appendOnly' => (bool)$t->getAppendOnly(),
+				'maxBytes' => $t->getMaxBytes(), 'storedBytes' => $this->alerts->lastStoredBytes($t)];
 		}
 		$runs = array_map(fn (Run $r) => $this->runJson($r), $this->runs->findRecent(15));
 		return new JSONResponse([
@@ -167,15 +168,25 @@ class AdminApiController extends Controller {
 		return new JSONResponse($this->targets->availableBackends());
 	}
 
-	public function addTarget(string $name, string $backend, string $auth, array $options = [], string $path = 'ng_backup'): JSONResponse {
+	public function addTarget(string $name, string $backend, string $auth, array $options = [], string $path = 'ng_backup', ?float $maxGb = null): JSONResponse {
 		try {
 			$r = $this->targets->add($name, $backend, $auth, $options, $path);
+			if ($maxGb !== null && $maxGb > 0) {
+				$this->targets->setMaxBytes($r['target'], (int)round($maxGb * 1073741824));
+			}
 		} catch (\Throwable $e) {
 			return new JSONResponse(['error' => $e->getMessage()], Http::STATUS_BAD_REQUEST);
 		}
 		return new JSONResponse(['id' => $r['target']->getId(), 'created' => $r['created']]);
 	}
 
+	/** Size limit in GiB; null or 0 = unlimited. */
+	#[PasswordConfirmationRequired]
+	public function setTargetLimit(int $id, ?float $maxGb = null): JSONResponse {
+		$t = $this->targets->setMaxBytes($this->targets->get((string)$id), ($maxGb !== null && $maxGb > 0) ? (int)round($maxGb * 1073741824) : null);
+		return new JSONResponse(['maxBytes' => $t->getMaxBytes()]);
+	}
+
 	#[PasswordConfirmationRequired]
 	public function removeTarget(int $id): JSONResponse {
 		$target = $this->targets->get((string)$id);

lib/Notification/Notifier.php

@@ -42,6 +42,10 @@ class Notifier implements INotifier {
 					: $l->t('Backup to %s failed', [$p['target']]));
 				$notification->setParsedMessage((string)($p['error'] ?? ''));
 				break;
+			case 'quota_warning':
+				$notification->setParsedSubject($l->t('Backup location %1$s is at %2$s%% of its limit (%3$s of %4$s)', [$p['target'], $p['percent'], $p['used'], $p['limit']]));
+				$notification->setParsedMessage($l->t('Backups stop when the limit is reached. Raise the limit, or let the retention policy remove older backups.'));
+				break;
 			case 'backup_stale':
 				$notification->setParsedSubject($l->t('No successful backup to %1$s since %2$s', [$p['target'], $p['since']]));
 				$notification->setParsedMessage($l->t('Check the backup settings and the server log.'));

lib/Service/AlertService.php

@@ -54,6 +54,36 @@ class AlertService {
 			['kind' => $run->getKind(), 'target' => $targetName, 'error' => mb_strimwidth((string)$run->getError(), 0, 300, '…')]);
 	}
 
+	/**
+	 * Remember how much is stored on a location (for the settings page) and warn administrators
+	 * once a day when it is at 80% of its limit or more.
+	 */
+	public function storedBytes(Target $target, int $bytes): void {
+		$this->appConfig->setValueString(Application::APP_ID, 'stored_' . $target->getId(), (string)$bytes);
+		$limit = $target->getMaxBytes();
+		if ($limit === null || $limit <= 0 || $bytes < 0.8 * $limit) {
+			return;
+		}
+		$key = 'quota_notified_' . $target->getId();
+		if ($this->appConfig->getValueString(Application::APP_ID, $key, '') === date('Y-m-d')) {
+			return;
+		}
+		$this->appConfig->setValueString(Application::APP_ID, $key, date('Y-m-d'));
+		$this->notifyAdmins('quota_warning', 'quota-' . $target->getId() . '-' . date('Y-m-d'), [
+			'target' => $target->getName(), 'percent' => (string)round($bytes / $limit * 100),
+			'used' => self::gib($bytes), 'limit' => self::gib($limit)]);
+	}
+
+	private static function gib(int $bytes): string {
+		$g = $bytes / 1073741824;
+		return sprintf($g < 10 ? '%.2f GiB' : '%.1f GiB', $g);
+	}
+
+	public function lastStoredBytes(Target $target): ?int {
+		$v = $this->appConfig->getValueString(Application::APP_ID, 'stored_' . $target->getId(), '');
+		return $v === '' ? null : (int)$v;
+	}
+
 	/** At most one notification per location per day. */
 	public function checkStale(Target $target): void {
 		$last = $this->runs->lastFinished($target->getId(), BackupService::KIND_FULL);

lib/Service/BackupService.php

@@ -149,6 +149,7 @@ class BackupService {
 				$state['files'] = BackupRun::step($repo, $state['files'], $deadline);
 				if ($state['files']['phase'] === 'done') {
 					$this->recordSnapshot($run, $state['files']);
+					$this->alerts->storedBytes($target, $repo->storedBytes());
 					$run->setStatus(Run::DONE);
 					$run->setPhase('done');
 					$run->setFinishedAt(time());

src/api.js

@@ -29,6 +29,7 @@ export default {
 	addTarget: (target) => call('post', '/targets', target),
 	removeTarget: (id) => call('delete', `/targets/${id}`),
 	testTarget: (id) => call('post', `/targets/${id}/test`),
+	setTargetLimit: (id, maxGb) => call('put', `/targets/${id}/limit`, { maxGb }),
 	startBackup: (targetId, label) => call('post', '/backups', { targetId, label }),
 	setSchedule: (time) => call('put', '/schedule', { time }),
 	snapshots: (targetId) => call('get', `/targets/${targetId}/snapshots`),

src/components/Locations.vue

@@ -8,7 +8,8 @@
 		<ul v-if="status.targets.length" class="ngb-list">
 			<li v-for="target in status.targets" :key="target.id">
 				<strong>{{ target.name }}</strong>
-				<span class="ngb-muted">{{ target.backend }} · {{ target.path }}</span>
+				<span class="ngb-muted">{{ target.backend }} · {{ target.path }}{{ target.appendOnly ? ' · ' + t('ng_backup', 'append-only') : '' }}</span>
+				<span :class="usageClass(target)">{{ usageText(target) }}</span>
 				<span v-if="tests[target.id]" :class="tests[target.id].ok ? 'ngb-ok' : 'ngb-err'">
 					{{ tests[target.id].ok ? t('ng_backup', 'OK, {n} snapshots', { n: tests[target.id].snapshots }) : tests[target.id].error }}
 				</span>
@@ -28,6 +29,8 @@
 				<NcTextField v-else v-model="form.options[field.key]" :label="field.label + (field.optional ? '' : ' *')" />
 			</template>
 			<NcTextField v-model="form.path" :label="t('ng_backup', 'Folder on the location for the backups')" />
+			<NcTextField v-model="form.maxGb" type="number" min="0" :label="t('ng_backup', 'Maximum size in GiB')"
+				:helper-text="form.maxGb ? t('ng_backup', 'Backups stop at this size; administrators are warned at 80%.') : t('ng_backup', 'Empty = unlimited: everything stored is billed by your provider, and nothing stops a backup that keeps growing.')" />
 			<div class="ngb-row">
 				<NcButton type="submit" variant="primary" :disabled="busy || !form.name || !backend || !auth">{{ t('ng_backup', 'Connect and add') }}</NcButton>
 				<NcButton @click="adding = false">{{ t('ng_backup', 'Cancel') }}</NcButton>
@@ -61,7 +64,18 @@ const backends = ref([])
 const backend = ref(null)
 const auth = ref(null)
 const tests = reactive({})
-const form = reactive({ name: '', path: 'ng_backup', options: {} })
+const form = reactive({ name: '', path: 'ng_backup', options: {}, maxGb: '' })
+
+const gib = (b) => (b / 1073741824).toFixed(1) + ' GiB'
+function usageText(target) {
+	if (target.storedBytes === null || target.storedBytes === undefined) {
+		return target.maxBytes ? t('ng_backup', 'limit {limit}', { limit: gib(target.maxBytes) }) : t('ng_backup', 'no limit')
+	}
+	return target.maxBytes
+		? t('ng_backup', '{used} of {limit}', { used: gib(target.storedBytes), limit: gib(target.maxBytes) })
+		: t('ng_backup', '{used} stored, no limit', { used: gib(target.storedBytes) })
+}
+const usageClass = (target) => (target.maxBytes && target.storedBytes >= 0.8 * target.maxBytes) ? 'ngb-err' : 'ngb-muted'
 
 // files_external DefinitionParameter: type 0 text, 1 boolean, 2 password; flag 1 = optional, 4 = hidden
 const toFields = (params) => Object.entries(params || {})
@@ -90,9 +104,10 @@ async function add() {
 	busy.value = true
 	error.value = ''
 	try {
-		await api.addTarget({ name: form.name, backend: backend.value.id, auth: auth.value.id, options: form.options, path: form.path })
+		await api.addTarget({ name: form.name, backend: backend.value.id, auth: auth.value.id, options: form.options, path: form.path,
+			maxGb: form.maxGb === '' ? null : Number(form.maxGb) })
 		adding.value = false
-		Object.assign(form, { name: '', path: 'ng_backup', options: {} })
+		Object.assign(form, { name: '', path: 'ng_backup', options: {}, maxGb: '' })
 		emit('changed')
 	} catch (e) {
 		error.value = e.message