Snapshot Limit và Retention Policy

Giới thiệu

Trong bài này, chúng ta sẽ tìm hiểu về snapshot limit management và retention policy để kiểm soát số lượng snapshots/backups.

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Snapshot Limit Check

Check Limit Before Create

export async function checkSnapshotLimitForManual(
  serverId: string,
  snapshotLimit: number,
  location?: string
): Promise<void> {
  // Normalize location
  const normalizedLocation = normalizeLocationForCheck(location);
  
  // Get actual snapshots from OpenStack
  const snapshots = await listServerSnapshotsOpenStack({
    serverId,
    location: normalizedLocation,
    limit: 1000,
  });
  
  // Filter by source (portal-manual or portal-auto)
  const filteredImages = filterSnapshotsBySource(snapshots);
  const totalCount = filteredImages.length;
  
  // Check if limit exceeded
  if (totalCount >= snapshotLimit) {
    throw errorSnapshotLimitExceeded;
  }
  
  // Get backup schedule retain value
  const retainValue = await getBackupScheduleRetain(serverId);
  
  // Check if total + retain would exceed limit
  const totalReserved = totalCount + retainValue;
  if (totalReserved >= snapshotLimit) {
    throw errorSnapshotLimitByScheduledBackup;
  }
}

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Filter Snapshots by Source

Filter Function

export function filterSnapshotsBySource(snapshots: any[]): any[] {
  if (!Array.isArray(snapshots)) {
    return [];
  }
  return snapshots.filter((snapshot) => {
    const source = snapshot?.source || '';
    return source === 'portal-manual' || source === 'portal-auto';
  });
}

Filter Logic:

• Chỉ lấy snapshots có source: 'portal-manual' hoặc source: 'portal-auto'
• Bỏ qua snapshots từ nguồn khác

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Retention Policy

Retain Count

interface IBackupSchedule {
  retain: number; // Number of backups to keep
  // ...
}

Cleanup Old Snapshots

// Cleanup old backups beyond retention limit
const toDelete = items.slice(schedule.retain);

for (const item of toDelete) {
  try {
    logger.info(`🗑️ Deleting old snapshot: ${item.name}`);
    await deleteCloudServerSnapshotService({
      id: Number(schedule.resourceId),
      customerEmail: schedule.customerEmail,
      snapshotImageId: item.id,
    });
    
    // Clean up metadata
    await SnapshotMeta.deleteOne({
      resourceType: 'cloud-server',
      resourceId: String(schedule.resourceId),
      providerSnapshotId: String(item.id),
    });
  } catch (e: any) {
    logger.warn(`⚠️ Error deleting snapshot: ${e?.message}`);
  }
}

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Limit Logic

Manual Snapshot

• Check: Total count < limit
• Error: errorSnapshotLimitExceeded

Scheduled Backup

• Check: Total count + retain < limit
• Error: errorSnapshotLimitByScheduledBackup
• Reason: Cần đảm bảo có đủ slot cho retain backups

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Best Practices

Check Limit Early

// ✅ DO: Check before creating
await checkSnapshotLimitForManual(serverId, snapshotLimit, location);
await createServerSnapshotOpenStack({ serverId, snapshotName, location });

// ❌ DON'T: Create first, check later
const result = await createServerSnapshotOpenStack({...});
if (tooManySnapshots) {
  await delete(result.imageId); // Wasteful
}

Sort by Date

// ✅ DO: Sort before slicing
items.sort((a, b) => 
  new Date(b.created_at).getTime() - new Date(a.created_at).getTime()
);
const toDelete = items.slice(schedule.retain);

// ❌ DON'T: Slice without sorting
const toDelete = items.slice(schedule.retain); // May delete wrong ones

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Summary

Key Points

1. Limit Check

   • Check before creating
   • Count actual snapshots from OpenStack
   • Filter by source

2. Retention Policy

   • Keep N latest backups
   • Delete oldest first
   • Clean up metadata

3. Error Handling

   • Different errors for manual vs scheduled
   • Clear error messages

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Next Steps

Trong bài tiếp theo, chúng ta sẽ tìm hiểu về:

• Production Practices - Best practices cho production

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Last Updated: 2025-01-25
Previous: 07. Multi-Location
Next: 09. Production Practices