/articles/storage-python-how-to-use-blob-storage.md

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# How to Use the Blob Storage Service from Python
This guide will show you how to perform common scenarios using the
Azure Blob storage service. The samples are written using the
Python API. The scenarios covered include **uploading**, **listing**,
**downloading**, and **deleting** blobs. For more information on blobs,
see the [Next Steps][] section.

## Table of Contents

[What is Blob Storage?][]   
 [Concepts][]   
 [Create an Azure Storage Account][]   
 [How To: Create a Container][]   
 [How To: Upload a Blob into a Container][]   
 [How To: List the Blobs in a Container][]   
 [How To: Download Blobs][]   
 [How To: Delete a Blob][]   
 [How To: Upload and Download Large Blobs][]   
 [Next Steps][]

[WACOM.INCLUDE [howto-blob-storage](../includes/howto-blob-storage.md)]

## <a name="create-account"> </a>Create an Azure Storage Account

[WACOM.INCLUDE [create-storage-account](../includes/create-storage-account.md)]

## <a name="create-container"> </a>How to: Create a Container

**Note:** If you need to install Python or the Client Libraries, please see the [Python Installation Guide](../python-how-to-install/).


The **BlobService** object lets you work with containers and blobs. The
following code creates a **BlobService** object. Add the following near
the top of any Python file in which you wish to programmatically access Azure Storage:

	from azure.storage import *

The following code creates a **BlobService** object using the storage account name and account key.  Replace 'myaccount' and 'mykey' with the real account and key.

	blob_service = BlobService(account_name='myaccount', account_key='mykey')

All storage blobs reside in a container. You can use a **BlobService** object to create the container if it doesn't exist:

	blob_service.create_container('mycontainer')

By default, the new container is private, so you must specify your storage access key (as you did above) to download blobs from this container. If you want to make the files within the container available to everyone, you can create the container and pass the public access level using the following code:

	blob_service.create_container('mycontainer', x_ms_blob_public_access='container') 

Alternatively, you can modify a container after you have created it using the following code:

	blob_service.set_container_acl('mycontainer', x_ms_blob_public_access='container')

After this change, anyone on the Internet can see blobs in a public
container, but only you can modify or delete them.

## <a name="upload-blob"> </a>How to: Upload a Blob into a Container

To upload a file to a blob, use the **put_blob** method
to create the blob, using a file stream as the contents of the blob.
First, create a file called **task1.txt** (arbitrary content is fine)
and store it in the same directory as your Python file.

	myblob = open(r'task1.txt', 'r').read()
	blob_service.put_blob('mycontainer', 'myblob', myblob, x_ms_blob_type='BlockBlob')

## <a name="list-blob"> </a>How to: List the Blobs in a Container

To list the blobs in a container, use the **list_blobs** method with a
**for** loop to display the name of each blob in the container. The
following code outputs the **name** and **url** of each blob in a container to the
console.

	blobs = blob_service.list_blobs('mycontainer')
	for blob in blobs:
		print(blob.name)
		print(blob.url)

## <a name="download-blobs"> </a>How to: Download Blobs

To download blobs, use the **get_blob** method to transfer the
blob contents to a stream object that you can then persist to a local
file.

	blob = blob_service.get_blob('mycontainer', 'myblob')
	with open(r'out-task1.txt', 'w') as f:
		f.write(blob)

## <a name="delete-blobs"> </a>How to: Delete a Blob

Finally, to delete a blob, call **delete_blob**.

	blob_service.delete_blob('mycontainer', 'myblob') 

## <a name="large-blobs"> </a>How to: Upload and Download Large Blobs

The maximum size for a block blob is 200 GB.  For blobs smaller than 64 MB, the blob can be uploaded or downloaded using a single call to **put\_blob** or **get\_blob**, as shown previously.  For blobs larger than 64 MB, the blob needs to be uploaded or downloaded in blocks of 4 MB or smaller.

The following code shows examples of functions to upload or download block blobs of any size.

    import base64

    chunk_size = 4 * 1024 * 1024

    def upload(blob_service, container_name, blob_name, file_path):
        blob_service.create_container(container_name, None, None, False)
        blob_service.put_blob(container_name, blob_name, '', 'BlockBlob')

        block_ids = []
        index = 0
        with open(file_path, 'rb') as f:
            while True:
                data = f.read(chunk_size)
                if data:
                    length = len(data)
                    block_id = base64.b64encode(str(index))
                    blob_service.put_block(container_name, blob_name, data, block_id)
                    block_ids.append(block_id)
                    index += 1
                else:
                    break

        blob_service.put_block_list(container_name, blob_name, block_ids)

    def download(blob_service, container_name, blob_name, file_path):
        props = blob_service.get_blob_properties(container_name, blob_name)
        blob_size = int(props['content-length'])

        index = 0
        with open(file_path, 'wb') as f:
            while index < blob_size:
                chunk_range = 'bytes={}-{}'.format(index, index + chunk_size - 1)
                data = blob_service.get_blob(container_name, blob_name, x_ms_range=chunk_range)
                length = len(data)
                index += length
                if length > 0:
                    f.write(data)
                    if length < chunk_size:
                        break
                else:
                    break

If you need blobs larger than 200 GB, you can use a page blob instead of a block blob.  The maximum size of a page blob is 1 TB, with pages that align to 512-byte page boundaries.  Use **put\_blob** to create a page blob, **put\_page** to write to it, and **get\_blob** to read from it.

## <a name="next-steps"> </a>Next Steps

Now that you’ve learned the basics of blob storage, follow these links
to learn how to do more complex storage tasks.

-   See the MSDN Reference: [Storing and Accessing Data in Azure][]
-   Visit the [Azure Storage Team Blog][]

  [Next Steps]: #next-steps
  [What is Blob Storage?]: #what-is
  [Concepts]: #concepts
  [Create an Azure Storage Account]: #create-account
  [How To: Create a Container]: #create-container
  [How To: Upload a Blob into a Container]: #upload-blob
  [How To: List the Blobs in a Container]: #list-blob
  [How To: Download Blobs]: #download-blobs
  [How To: Delete a Blob]: #delete-blobs
  [How To: Upload and Download Large Blobs]: #large-blobs
  [Storing and Accessing Data in Azure]: http://msdn.microsoft.com/en-us/library/windowsazure/gg433040.aspx
  [Azure Storage Team Blog]: http://blogs.msdn.com/b/windowsazurestorage/