WopiHost.AzureStorageProvider 8.0.0

WopiHost.AzureStorageProvider

IWopiStorageProvider + IWopiWritableStorageProvider backed by Azure Blob Storage. WOPI files map directly to blobs; folders are virtual prefixes with a hidden zero-byte marker so empty folders remain addressable.

Suitable for production multi-instance deployments. Use with WopiHost.AzureLockProvider for distributed locking.

Install

dotnet add package WopiHost.AzureStorageProvider

Configure

Two authentication modes — connection string (Azurite, dev) and TokenCredential (managed identity, service principal):

// appsettings.json — connection string
"Wopi": {
  "StorageProvider": {
    "ConnectionString": "UseDevelopmentStorage=true",
    "ContainerName": "wopi-files"
  }
}

// appsettings.json — DefaultAzureCredential
"Wopi": {
  "StorageProvider": {
    "ServiceUri": "https://my-account.blob.core.windows.net",
    "ContainerName": "wopi-files"
  }
}

When ServiceUri is used the provider resolves a TokenCredential from DI; if none is registered, DefaultAzureCredential is created automatically. Register your own to override:

builder.Services.AddSingleton<TokenCredential>(new ManagedIdentityCredential(clientId));

The container is created on first use if it doesn't exist.

Register

builder.Services.AddAzureStorageProvider(builder.Configuration);
builder.Services.AddWopi(o =>
{
    o.ClientUrl = new Uri("https://your-office-online-server.com");
});

The runnable sample exposes a small Sample:StorageProvider discriminator (FileSystem / Azure) and dispatches to the chosen provider's typed extension — see sample/WopiHost/ServiceCollectionExtensions.cs.

How it maps to Blob Storage

The provider scans the container at first access to populate the in-memory id-to-path map. Identifiers are stable across process restarts (deterministic from path) but not across renames — a rename re-points the existing id to the new path so the WOPI URL doesn't break mid-edit.

Caveats

• Folder rename / delete-folder are O(N) over the children — plain Blob has no atomic prefix rename. If you do this often, consider switching to ADLS Gen2 (not currently supported, see issue #26) for atomic rename via the DFS endpoint.
• Empty folders are materialised by writing a zero-byte .wopi.folder blob. Listings filter it out; deleting an empty folder removes the marker and drops the id.
• SHA-256 is computed streaming on upload via HashingBlobWriteStream and stored as metadata. Pre-existing blobs that were not written through this provider will return null from Checksum until they are next written.
• Owner is read from blob metadata; the provider doesn't set an owner on its own. Hosts that care about ownership should set wopi_owner themselves (e.g. via a custom write pipeline that enriches metadata after GetWriteStream).

Local development

The provider works against Azurite. The repo's Aspire AppHost runs Azurite as a container resource when AppHost:UseAzureStorage=true:

AppHost__UseAzureStorage=true dotnet run --project infra/WopiHost.AppHost

The Aspire orchestrator forwards the emulator connection string into WopiHost as ConnectionStrings:BlobStorage, which you can map into Wopi:StorageProvider:ConnectionString via standard configuration substitution.

License

See the repo README.