How to Download Blob from Azure in Python Using Client Credentials

Learn how to troubleshoot and resolve the Not Authorized error when downloading Blobs from Azure Blob Storage in Python using client credentials.
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This video is based on the question https://stackoverflow.com/q/76739122/ asked by the user 'Mayukh Chakravartti' ( https://stackoverflow.com/u/14081648/ ) and on the answer https://stackoverflow.com/a/76740220/ provided by the user 'Xiang Yan' ( https://stackoverflow.com/u/5886729/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Downloading Blob from Azure in Python Using Client Credentials

Azure Blob Storage can be an exciting and powerful feature for managing large amounts of unstructured data. However, developers often encounter obstacles such as authorization issues when attempting to access or manipulate these resources. One common challenge is receiving a "Not Authorized" error when trying to download a Blob using client credentials in Python. If you find yourself in this situation, you’re not alone, and this guide is here to help.

Understanding the Problem

You may have the following setup:

An Azure container filled with files.

An Azure AD account equipped with client credentials.

A Python script aimed at downloading a Blob, but you are met with a “Not Authorized” error.

Your initial code snippet may look similar to this:

[[See Video to Reveal this Text or Code Snippet]]

Despite following these steps, you might be left wondering what went wrong.

Potential Solutions

1. Verify Token Retrieval

First and foremost, ensure that you are retrieving the access token correctly. You should include a call to get_token like this:

[[See Video to Reveal this Text or Code Snippet]]

This line ensures that you are acquiring the necessary token for accessing Azure Blob Storage. If this command fails or returns an error, it suggests that there may be issues with the client credentials provided.

2. Check Permissions

If you successfully obtain a token, the next step is to verify the permissions attached to your service principal. Ensure that it is granted the following access rights:

Storage Blob Data Contributor – This role allows the service principal to read, write, and delete blobs.

Storage Blob Data Reader – This role enables the service principal to only read blob data.

Without the appropriate permissions, you will continue to encounter authorization problems.

3. Validate Credentials

Misconfiguration of the credentials can also lead to authentication failures. Hence, double-check that you've correctly input the following:

tenantId – Your Azure AD tenant ID.

clientId – The application (client) ID for your app registration.

clientSecret – The secret key associated with your app registration.

Confirm that the values you have used are accurate and correspond to the Azure AD application created for this purpose.

Conclusion

Encountering a "Not Authorized" error while trying to access Azure Blob Storage using client credentials can be frustrating. By following the steps above—verifying token retrieval, checking permissions, and validating your credentials—you can diagnose and resolve the issue effectively.

By understanding these elements, you will harness the power of Azure Blob Storage securely and efficiently. If you continue to experience difficulties after trying these solutions, consider reaching out to Azure support for additional assistance.

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