Introduction to Event Capture

Azure Event Hubs is a highly scalable data streaming platform and event ingestion service. One of its powerful features is the ability to automatically capture the data in Event Hubs and archive it to an Azure Blob Storage or Azure Data Lake Storage account.

This guide will walk you through the process of setting up and configuring Event Hubs Capture for your event streams.

Why Use Event Hubs Capture?

  • Archiving: Provides a durable and cost-effective way to store event data for compliance, auditing, or batch processing.
  • Integration: Seamlessly integrates with other Azure services like Azure Databricks, Azure Synapse Analytics, and Azure Stream Analytics for downstream processing.
  • Batching: Data is captured in batches, optimized for analytical workloads.
  • Simplicity: Managed by Azure, requiring minimal configuration and operational overhead.

Prerequisites

  • An Azure subscription.
  • An existing Azure Event Hubs namespace and an Event Hub.
  • An Azure Blob Storage account or Azure Data Lake Storage Gen2 account with a container.

Enabling Event Hubs Capture

You can enable Event Hubs Capture through the Azure portal, Azure CLI, or ARM templates.

Using the Azure Portal

  1. Navigate to your Event Hubs namespace in the Azure portal.
  2. In the left-hand menu, under "Settings", select "Features".
  3. Find the "Capture" section and click "Enable".
  4. Configure the following settings:
    • Destination: Choose either "Azure Blob Storage" or "Azure Data Lake Storage Gen2".
    • Storage Account: Select your storage account.
    • Container: Choose the container where data will be archived.
    • Capture interval (minutes): Set how often data should be captured (e.g., every 5 minutes).
    • Encoding: Select the desired file encoding (e.g., Avro, Parquet). Avro is the default and recommended for many analytical scenarios.
  5. Click "Save".

Using Azure CLI

You can enable capture using the following Azure CLI command. Replace placeholders with your actual values.

az eventhubs namespace update --resource-group <YourResourceGroup> --name <YourNamespaceName> --enable-capture true --capture-storage-account <YourStorageAccountName> --capture-container <YourContainerName> --capture-interval <IntervalInMinutes> --capture-encoding <EncodingFormat>

Understanding Captured Data Format

When Capture is enabled, Event Hubs writes events to the configured storage account. The data is organized into files with a specific naming convention and format:

  • File Naming: The files are typically named using a pattern that includes the namespace, event hub, partition ID, capture start time, capture end time, and a sequence number. For example: yournamespace/your-eventhub/PT5M/2023/10/27/10/14/0000000000.avro
  • Avro Format: By default, events are captured in Apache Avro format. This is a binary format that is efficient for storage and processing, and it preserves the schema of your events.
  • Parquet Format: You can also choose to capture data in Apache Parquet format, which is columnar and optimized for analytical queries.

Monitoring Captured Data

After enabling Capture, you can monitor the archived data directly in your Blob Storage or Data Lake Storage account. The files will appear periodically based on your configured capture interval.

Best Practices

  • Choose the Right Interval: Balance the need for timely archiving with storage costs. Shorter intervals mean more frequent, smaller files.
  • Select Appropriate Encoding: Avro is generally recommended for broad compatibility, while Parquet excels in analytical performance.
  • Secure Your Storage Account: Ensure your storage account has appropriate access policies and network security configured.
  • Monitor Storage Usage: Keep an eye on your storage account's capacity and costs.

Conclusion

Azure Event Hubs Capture provides a robust and effortless solution for archiving your event streams. By following these steps, you can ensure your valuable event data is reliably stored for future analysis and compliance needs.