Download Blob From Blob Storage Using Python

Question

I am trying to download an excel file on a blob. However, it keeps generating the error "The specified blob does not exist". This error happens at blob_client.download_blob() although I can get the blob_client. Any idea why or other ways I can connect using managed identity?

default_credential = DefaultAzureCredential()
 
blob_url = BlobServiceClient('url', credential = default_credential)
   
container_client = blob_url.get_container_client('xx-xx-data')

blob_client = container_client.get_blob_client('TEST.xlsx')

downloaded_blob = blob_client.download_blob()

df=pd.read_excel(downloaded_blob.content_as_bytes(), sheet_name='Test',skiprows=2)

Can you please confirm if TEST.xlsx blob exists in it-dashboards-data blob container? — Gaurav Mantri
– Gaurav Mantri, Commented May 3, 2021 at 11:10
Please note that blob names are case sensitive. Blob should be exactly named TEST.xlsx. — Gaurav Mantri
– Gaurav Mantri, Commented May 3, 2021 at 11:20
Is the url simple blob URL like https://account.blob.core.windows.net/container/blob or is it a SAS URL? — Gaurav Mantri
– Gaurav Mantri, Commented May 3, 2021 at 11:24

Kelly · Accepted Answer · 2021-05-04 03:01:45Z

1

Turns out that I have to also provide 'Reader' access on top of 'Storage Blob Data Contributor' to be able to identify the blob. There was no need for SAS URL.

answered May 4, 2021 at 3:01

Kelly

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Gaurav Mantri · Accepted Answer · 2021-05-03 12:34:31Z

0

The reason you're getting this error is because each request to Azure Blob Storage must be an authenticated request. Only exception to this is when you're reading (downloading) a blob from a public blob container. In all likelihood, the blob container holding this blob is having a Private ACL and since you're sending an unauthenticated request, you're getting this error.

I would recommend using a Shared Access Signature (SAS) URL for the blob with Read permission instead of simple blob URL. Since a SAS URL has authorization information embedded in the URL itself (sig portion), you should be able to download the blob provided SAS is valid and has not expired.

Please see this for more information on Shared Access Signature: https://learn.microsoft.com/en-us/rest/api/storageservices/delegate-access-with-shared-access-signature.

answered May 3, 2021 at 12:34

Gaurav Mantri

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3 Comments

Kelly Over a year ago

Is there a way to create SAS URL using DefaultAzureCredential()? I have to just download a blob using managed identity. I'd read through the link and can't seem to get it working.

Gaurav Mantri Over a year ago

Can you confirm if managed identity is working for you? Are you running the code in Azure or locally?

Kelly Over a year ago

Yes it’s working correctly. I’m already using managed identity for authenticating with SQL. Just that I’m having issues with storage blob. I’m testing locally and in Azure, both seems to have issues

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