Spring Cloud Azure resource handling

Article
06/07/2024

This article applies to: ✅ Version 4.19.0 ✅ Version 5.19.0

The Spring project provides a Spring Resources abstraction to access a number of low-level resources. The project provides interfaces like Resource, ResourceLoader and ResourcePatternResolver. Spring Cloud Azure implements these interfaces for Azure Storage services, which allows you to interact with Azure storage Blob and File Share using the Spring programming model. Spring Cloud Azure provides spring-cloud-azure-starter-storage-blob and spring-cloud-azure-starter-storage-file-share to auto-configure Azure Storage Blob and Azure Storage File Share.

The following table lists Azure Storage related libraries:

Starter	Service	Description
spring-cloud-azure-starter-storage-blob	Azure Storage Blob	Allows unstructured data to be stored and accessed at a massive scale in block blobs.
spring-cloud-azure-starter-storage-file-share	Azure Storage File Share	Offers fully managed cloud file shares that you can access from anywhere via the industry standard Server Message Block (SMB) protocol.

Dependency setup

<dependencies>
    <dependency>
        <groupId>com.azure.spring</groupId>
        <artifactId>spring-cloud-azure-starter-storage-blob</artifactId>
    </dependency>
    <dependency>
        <groupId>com.azure.spring</groupId>
        <artifactId>spring-cloud-azure-starter-storage-file-share</artifactId>
    </dependency>
</dependencies>

The spring-cloud-azure-starter-storage-blob dependency is only required when you're using Azure Storage Blob.

The spring-cloud-azure-starter-storage-file-share dependency is only required when you're using Azure Storage File Share.

Tip

We also provide spring-cloud-azure-starter-storage to support all the features of Storage. If you choose to use it, spring.cloud.azure.storage.enable is the property to configure and the default value is true. You can then use spring.cloud.azure.storage.<storage-service>.enable to disable unneeded services.

Configuration

Note

If you use a security principal to authenticate and authorize with Microsoft Entra ID for accessing an Azure resource, be sure the security principal has been granted sufficient permission to access the Azure resource. For more information, see Authorize access with Microsoft Entra ID.

The following table lists the configurable properties of spring-cloud-azure-starter-storage-blob:

Property	Default	Description
spring.cloud.azure.storage.blob.enabled	true	A value that indicates whether an Azure Blob Storage service is enabled.
spring.cloud.azure.storage.blob.endpoint		The URI to connect to Azure Blob Storage.
spring.cloud.azure.storage.blob.account-key		The private key to connect to Azure Blob Storage.
spring.cloud.azure.storage.blob.account-name		The Azure Storage Blob account name.

The following table lists the configurable properties of spring-cloud-azure-starter-storage-file-share:

Property	Default	Description
spring.cloud.azure.storage.fileshare.enabled	true	A value that indicates whether Azure File Storage service is enabled.
spring.cloud.azure.storage.fileshare.endpoint		The URI to connect to Azure File Storage.
spring.cloud.azure.storage.fileshare.account-key		The private key to connect to Azure File Storage.
spring.cloud.azure.storage.fileshare.account-name		The Azure Storage File Share account name.

Basic usage

Add the following properties to your application.yml file:

spring:
  cloud:
    azure:
      storage:
        blob:
          account-name: ${STORAGE_ACCOUNT_NAME}
          account-key: ${STORAGE_ACCOUNT_KEY}
          endpoint: ${STORAGE_BLOB_ENDPOINT}
        fileshare:
          account-name: ${STORAGE_ACCOUNT_NAME}
          account-key: ${STORAGE_ACCOUNT_KEY}
          endpoint:  ${STORAGE_FILESHARE_ENDPOINT}

Get a resource

Get a resource with @Value

You can use the annotation of @Value("azure-blob://[your-container-name]/[your-blob-name]") to autowire a blob resource, as shown in the following example:

@Value("azure-blob://[your-container-name]/[your-blob-name]")
private Resource storageBlobResource;

You can use the annotation of @Value("azure-file://[your-fileshare-name]/[your-file-name]") to autowire a file resource, as shown in the following example:

@Value("azure-file://[your-fileshare-name]/[your-file-name]")
private Resource storageFileResource;

Get a resource with ResourceLoader

@Autowired
private ResourceLoader resourceLoader;
...
// Get a BlobResource.
Resource storageBlobResource = resourceLoader.getResource("azure-blob://[your-container-name]/[your-blob-name]");

// Get a FileResource.
Resource storageFileResource = resourceLoader.getResource("azure-file://[your-fileshare-name]/[your-file-name]");

Get resources by searching pattern

You can use an implementation class of ResourcePatternResolver to search resources. Use AzureStorageBlobProtocolResolver to search blob resources and AzureStorageFileProtocolResolver to search file resources.

For pattern search, the searchPattern should start with azure-blob:// or azure-file://. For example, azure-blob://**/** means to list all blobs in all containers, and azure-blob://demo-container/** means to list all blobs in the demo-container container, including any sub-folder.
For location search, the searchLocation should start with azure-blob:// or azure-file:// and the remaining file path should exist, otherwise an exception will be thrown.

@Autowired
private AzureStorageBlobProtocolResolver azureStorageBlobProtocolResolver;

@Autowired
private AzureStorageFileProtocolResolver azureStorageFileProtocolResolver;

// Get all text blobs.
Resource[] blobTextResources = azureStorageBlobProtocolResolver.getResources("azure-blob://[container-pattern]/*.txt");

// Get all text files.
Resource[] fileTextResources = azureStorageFileProtocolResolver.getResources("azure-file://[fileshare-pattern]/*.txt");

Handling with resource

Download data from specific resource

You can download a resource from Azure Storage Blob or File Share with the getInputStream() method of Resource.

@Value("azure-blob://[your-container-name]/[your-blob-name]")
private Resource storageBlobResource;

@Value("azure-file://[your-fileshare-name]/[your-file-name]")
private Resource storageFileResource;

//...

// Download data as a stream from a blob resource.
InputStream inputblobStream = storageBlobResource.getInputStream();

// Download data as a stream from a file resource.
InputStream inputfileStream = storageFileResource.getInputStream();

Upload data to specific resource

You can upload to a resource to Azure Blob or file storage by casting the Spring Resource to WritableResource, as shown in the following example:

@Value("azure-blob://[your-container-name]/[your-blob-name]")
private Resource storageBlobResource;

@Value("azure-file://[your-fileshare-name]/[your-file-name]")
private Resource storageFileResource;

String data = "sampledata";

// Upload string data to a blob.
try (OutputStream blobos = ((WritableResource) this.storageBlobResource).getOutputStream()) {
    blobos.write(data.getBytes());
}

// Upload string data to a file.
try (OutputStream fileos = ((WritableResource) this.storageFileResource).getOutputStream()) {
    fileos.write(data.getBytes());
}

Multipart upload

Files larger than 4 MiB will be uploaded to Azure Storage in parallel.

Samples

See the storage-blob-sample and storage-file-sample repositories on GitHub.

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