Azure Blob Storage Data Bus

Usage

endpointConfiguration.UseDataBus<AzureDataBus>();

Cleanup strategies

Discarding old Azure Data Bus attachments can be done in one of the following ways:

1. Using an Azure Durable Function
2. Using the Blob Lifecycle Management policy

Using an Azure Durable Function

Review the Azure Blob Storage Data Bus cleanup with Azure Functions sample to see how to use a durable function to clean up attachments.

Using the Blob Lifecycle Management policy

Attachment blobs can be cleaned up using the Blob Storage Lifecycle feature. This method allows configuring a single policy for all data bus-related blobs. Those blobs can be either deleted or archived. The policy does not require custom code and is deployed directly to the storage account. This feature can only be used on GPv2 and Blob storage accounts, not on GPv1 accounts.

How lifecycle rules relate to Azure Blob Storage Databus settings

When creating a rule the blob prefix match filter setting should be set to the value of databus/ by default. If the Container() or BasePath() configuration options have been specified when configuring the data bus the blob prefix match filter setting must be modified to take into account the configured container and/or base path values.

Manage the Blob Lifecycle policy via Azure portal

A lifecycle management policy can be set directly on the azure storage account via the portal. Additional information on the configuration, can be found in azure blob lifecycle management policy

Manage the Blob Lifecycle policy via the Azure Command-Line Interface (CLI)

The lifecycle management policy can be set in a JSON document via the Azure CLI.

{
  "rules": [
    {
      "enabled": true,
      "name": "delete-databus-files",
      "type": "Lifecycle",
      "definition": {
        "actions": {
          "version": {
            "delete": {
              "daysAfterCreationGreaterThan": 90
            }
          },
          "baseBlob": {
            "tierToCool": {
              "daysAfterModificationGreaterThan": 30
            },
            "tierToArchive": {
              "daysAfterModificationGreaterThan": 90,
              "daysAfterLastTierChangeGreaterThan": 7
            },
            "delete": {
              "daysAfterModificationGreaterThan": 2555
            }
          }
        },
        "filters": {
          "blobTypes": [
            "blockBlob"
          ],
          "prefixMatch": [
            "databus/"
          ]
        }
      }
    }
  ]
}

The data policy rules associated with the specified storage account can be created as follows.

az storage account management-policy create --account-name myaccount --policy @policy.json --resource-group myresourcegroup

Configuration

Configuring the BlobServiceClient

There are several ways to configure the BlobServiceClient.

Using a preconfigured BlobServiceClient

A fully configured BlobServiceClient can be set through the settings:

var serviceClient = new BlobServiceClient("connectionString");
endpointConfiguration.UseDataBus<AzureDataBus>()
                     .UseBlobServiceClient(serviceClient);

Using a custom provider

A custom provider can be declared that provides a fully configured BlobServiceClient:

public class CustomProvider : IProvideBlobServiceClient
{
    // Leverage dependency injection to use a custom-configured BlobServiceClient
    public CustomProvider(BlobServiceClient serviceClient)
    {
        Client = serviceClient;
    }

    public BlobServiceClient Client { get; }
}

The provider is then registered in the dependency injection container:

endpointConfiguration.UseDataBus<AzureDataBus>();
endpointConfiguration.RegisterComponents(services => services.RegisterSingleton(typeof(CustomProvider)));

Providing a connection string and container name

endpointConfiguration.UseDataBus<AzureDataBus>()
    .ConnectionString("connectionString")
    .Container("containerName");

Token-credentials

Enables usage of Microsoft Entra ID authentication such as managed identities for Azure resources instead of the shared secret in the connection string.

With a preconfigured BlobServiceClient

var serviceClient = new BlobServiceClient(new Uri("https://<account-name>.blob.core.windows.net"), new DefaultAzureCredential());
endpointConfiguration.UseDataBus<AzureDataBus>()
    .UseBlobServiceClient(serviceClient);

With Microsoft.Extensions.Azure

builder.Services.AddAzureClients(azureClients =>
{
    azureClients.AddBlobServiceClient(new Uri("https://<account-name>.blob.core.windows.net"));
    azureClients.UseCredential(new DefaultAzureCredential());
});
builder.Services.AddSingleton<IProvideBlobServiceClient, CustomProvider>();

Behavior

The following extension methods are available for changing the behavior of AzureDataBus defaults:

var dataBus = endpointConfiguration.UseDataBus<AzureDataBus>();
dataBus.ConnectionString(azureStorageConnectionString);
dataBus.Container(containerName);
dataBus.BasePath(basePathWithinContainer);
dataBus.MaxRetries(maxNumberOfRetryAttempts);
dataBus.NumberOfIOThreads(numberOfIoThreads);
dataBus.BackOffInterval(backOffIntervalBetweenRetriesInSecs);

• ConnectionString(): The connection string to the storage account for storing databus properties; defaults to UseDevelopmentStorage=true.
• Container(): Container name; defaults to databus.
• BasePath(): The blobs' base path in the container; defaults to an empty string.
• MaxRetries: Number of upload/download retries; defaults to 5 retries.
• NumberOfIOThreads: Number of blocks that will be simultaneously uploaded; defaults to 1 thread.
• BackOffInterval: The back-off time between retries; defaults to 30 seconds.