Version: Next

Azure Blob Storage

Overview

The RCommon.Azure.Blobs package wraps the official Azure Blob Storage SDK (Azure.Storage.Blobs) behind the IBlobStorageService interface. Your application code uses the provider-agnostic interface while the Azure implementation handles all SDK-specific details.

Multiple stores can be registered under different names, which is useful when different containers should use different credentials or service URIs (for example, a development emulator alongside a production account).

Installation

NuGet Package

dotnet add package RCommon.Azure.Blobs

This package depends on RCommon.Blobs and will bring it in automatically.

Configuration

Call WithBlobStorage<AzureBlobStorageBuilder> inside your AddRCommon() block. Use AddBlobStore to register each named store. Provide either a connection string or a service URI combined with a TokenCredential.

Using a connection string

A connection string is the simplest option for development and for environments where managed identity is not available.

using RCommon;
using RCommon.Azure.Blobs;

builder.Services.AddRCommon()
    .WithBlobStorage<AzureBlobStorageBuilder>(azure =>
    {
        azure.AddBlobStore("primary", opts =>
        {
            opts.ConnectionString = builder.Configuration
                .GetConnectionString("AzureStorage");
        });
    });

Typical appsettings.json:

{
  "ConnectionStrings": {
    "AzureStorage": "DefaultEndpointsProtocol=https;AccountName=myaccount;AccountKey=...;EndpointSuffix=core.windows.net"
  }
}

For local development with the Azurite emulator:

{
  "ConnectionStrings": {
    "AzureStorage": "UseDevelopmentStorage=true"
  }
}

Using a service URI with managed identity

Managed identity avoids storing credentials in configuration. Pass the storage account endpoint URI and a DefaultAzureCredential (or any other TokenCredential from Azure.Identity).

using Azure.Identity;
using RCommon;
using RCommon.Azure.Blobs;

builder.Services.AddRCommon()
    .WithBlobStorage<AzureBlobStorageBuilder>(azure =>
    {
        azure.AddBlobStore("primary", opts =>
        {
            opts.ServiceUri = new Uri(
                "https://myaccount.blob.core.windows.net");
            opts.Credential = new DefaultAzureCredential();
        });
    });

Registering multiple stores

builder.Services.AddRCommon()
    .WithBlobStorage<AzureBlobStorageBuilder>(azure =>
    {
        azure.AddBlobStore("uploads", opts =>
            opts.ConnectionString = uploadsConnectionString);

        azure.AddBlobStore("backups", opts =>
        {
            opts.ServiceUri = new Uri(
                "https://backupaccount.blob.core.windows.net");
            opts.Credential = new DefaultAzureCredential();
        });
    });

Usage

Inject IBlobStoreFactory and resolve the store by name, or inject IBlobStorageService directly when only one store is registered.

public class FileUploadService
{
    private readonly IBlobStorageService _storage;

    public FileUploadService(IBlobStoreFactory factory)
    {
        _storage = factory.Resolve("uploads");
    }

    public async Task UploadAsync(string fileName, Stream content,
        CancellationToken ct = default)
    {
        // Ensure the container exists before uploading.
        if (!await _storage.ContainerExistsAsync("user-files", ct))
            await _storage.CreateContainerAsync("user-files", ct);

        await _storage.UploadAsync(
            containerName: "user-files",
            blobName: fileName,
            content: content,
            options: new BlobUploadOptions { ContentType = "application/octet-stream" },
            token: ct);
    }

    public async Task<Stream> DownloadAsync(string fileName,
        CancellationToken ct = default)
    {
        return await _storage.DownloadAsync("user-files", fileName, ct);
    }
}

API Summary