optimizing-azure-blob-storage-cost

Optimizing Azure Blob Storage Cost

Default-low-cost blob storage with lifecycle rules tuned for media workloads (and any pattern with ephemeral temp blobs + long-lived primary blobs).

When to invoke

• Adding a blob storage account to a project
• Designing for uploads (SAS-based) + serving (Range / CORS)
• Auditing an existing storage account that's growing unbounded
• A project that stores media (video, large images, archives) where retention > 60 days

The two-pattern playbook

Pattern A: temp + permanent containers

Most apps have two flavours of blob:

• Temp — short-lived working data (uploads being processed, intermediate transformations, cache)
• Permanent — user-visible content (videos, images, exports)

Apply different lifecycle rules to each:

resource tempBlobLifecycle 'Microsoft.Storage/storageAccounts/managementPolicies@2023-05-01' = {
  parent: storageAccount
  name: 'default'
  properties: {
    policy: {
      rules: [
        // Rule 1: delete stale temp blobs after 7 days
        {
          enabled: true
          name: 'delete-stale-temp-blobs'
          type: 'Lifecycle'
          definition: {
            filters: {
              blobTypes: ['blockBlob']
              prefixMatch: ['incoming/', 'processor-jobs/', 'tmp/']
            }
            actions: {
              baseBlob: { delete: { daysAfterModificationGreaterThan: 7 } }
            }
          }
        }
        // Rule 2: age permanent blobs through tiers — NEVER use Archive for
        // playable/viewable content (rehydration takes hours)
        {
          enabled: true
          name: 'tier-aging-content'
          type: 'Lifecycle'
          definition: {
            filters: {
              blobTypes: ['blockBlob']
              prefixMatch: ['videos/', 'images/', 'exports/']
            }
            actions: {
              baseBlob: {
                tierToCool: { daysAfterModificationGreaterThan: 60 }
                tierToCold: { daysAfterModificationGreaterThan: 180 }
                // intentionally NO tierToArchive — needs rehydration
              }
            }
          }
        }
      ]
    }
  }
}