Manage container properties and metadata with Python
Blob containers support system properties and user-defined metadata, in addition to the data they contain. This article shows how to manage system properties and user-defined metadata with the Azure Storage client library for Python.
To learn about managing properties and metadata using asynchronous APIs, see Set container metadata asynchronously.
Prerequisites
- This article assumes you already have a project set up to work with the Azure Blob Storage client library for Python. To learn about setting up your project, including package installation, adding
import
statements, and creating an authorized client object, see Get started with Azure Blob Storage and Python. - The authorization mechanism must have permissions to work with container properties or metadata. To learn more, see the authorization guidance for the following REST API operations:
About properties and metadata
System properties: System properties exist on each Blob Storage resource. Some of them can be read or set, while others are read-only. Behind the scenes, some system properties correspond to certain standard HTTP headers. The Azure Storage client library for Python maintains these properties for you.
User-defined metadata: User-defined metadata consists of one or more name-value pairs that you specify for a Blob storage resource. You can use metadata to store additional values with the resource. Metadata values are for your own purposes only, and don't affect how the resource behaves.
Metadata name/value pairs are valid HTTP headers and should adhere to all restrictions governing HTTP headers. For more information about metadata naming requirements, see Metadata names.
Retrieve container properties
To retrieve container properties, use the following method:
The following code example fetches a container's system properties and writes the property values to a console window:
def get_properties(self, blob_service_client: BlobServiceClient, container_name):
container_client = blob_service_client.get_container_client(container=container_name)
properties = container_client.get_container_properties()
print(f"Public access type: {properties.public_access}")
print(f"Lease status: {properties.lease.status}")
print(f"Lease state: {properties.lease.state}")
print(f"Has immutability policy: {properties.has_immutability_policy}")
Set and retrieve metadata
You can specify metadata as one or more name-value pairs on a blob or container resource. To set metadata, use the following method:
Setting container metadata overwrites all existing metadata associated with the container. It's not possible to modify an individual name-value pair.
The following code example sets metadata on a container:
def set_metadata(self, blob_service_client: BlobServiceClient, container_name):
container_client = blob_service_client.get_container_client(container=container_name)
# Retrieve existing metadata, if desired
metadata = container_client.get_container_properties().metadata
more_metadata = {'docType': 'text', 'docCategory': 'reference'}
metadata.update(more_metadata)
# Set metadata on the container
container_client.set_container_metadata(metadata=metadata)
To retrieve metadata, call the following method:
The following example reads in metadata values:
def get_metadata(self, blob_service_client: BlobServiceClient, container_name):
container_client = blob_service_client.get_container_client(container=container_name)
# Retrieve existing metadata, if desired
metadata = container_client.get_container_properties().metadata
for k, v in metadata.items():
print(k, v)
Set container metadata asynchronously
The Azure Blob Storage client library for Python supports managing container properties and metadata asynchronously. To learn more about project setup requirements, see Asynchronous programming.
Follow these steps to set container metadata using asynchronous APIs:
Add the following import statements:
import asyncio from azure.identity.aio import DefaultAzureCredential from azure.storage.blob.aio import BlobServiceClient
Add code to run the program using
asyncio.run
. This function runs the passed coroutine,main()
in our example, and manages theasyncio
event loop. Coroutines are declared with the async/await syntax. In this example, themain()
coroutine first creates the top levelBlobServiceClient
usingasync with
, then calls the method that sets the container metadata. Note that only the top level client needs to useasync with
, as other clients created from it share the same connection pool.async def main(): sample = ContainerSamples() # TODO: Replace <storage-account-name> with your actual storage account name account_url = "https://<storage-account-name>.blob.core.windows.net" credential = DefaultAzureCredential() async with BlobServiceClient(account_url, credential=credential) as blob_service_client: await sample.set_metadata(blob_service_client, "sample-container") if __name__ == '__main__': asyncio.run(main())
Add code to set the container metadata. The code is the same as the synchronous example, except that the method is declared with the
async
keyword and theawait
keyword is used when calling theget_container_properties
andset_container_metadata
methods.async def set_metadata(self, blob_service_client: BlobServiceClient, container_name): container_client = blob_service_client.get_container_client(container=container_name) # Retrieve existing metadata, if desired metadata = (await container_client.get_container_properties()).metadata more_metadata = {'docType': 'text', 'docCategory': 'reference'} metadata.update(more_metadata) # Set metadata on the container await container_client.set_container_metadata(metadata=metadata)
With this basic setup in place, you can implement other examples in this article as coroutines using async/await syntax.
Resources
To learn more about setting and retrieving container properties and metadata using the Azure Blob Storage client library for Python, see the following resources.
REST API operations
The Azure SDK for Python contains libraries that build on top of the Azure REST API, allowing you to interact with REST API operations through familiar Python paradigms. The client library methods for setting and retrieving properties and metadata use the following REST API operations:
- Get Container Properties (REST API)
- Set Container Metadata (REST API)
- Get Container Metadata (REST API)
The get_container_properties
method retrieves container properties and metadata by calling both the Get Container Properties operation and the Get Container Metadata operation.
Code samples
- View synchronous or asynchronous code samples from this article (GitHub)
Client library resources
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