How to resolve issues with Azure Function App failing to copy data to certain Cosmos VC destination folders in ADF pipelines?

Question

I have an Azure Function App with a function called CopySSFile. I typically use this function in an ADF pipeline to copy data to a specified directory. The destination folder is usually a path in my team's Cosmos VC, such as https://www.cosmos08.osdinfra.net/cosmos/Bingads.algo.prod.IntentMatching/local, often under the /local/Team/ directory.

I recently discovered that CopySSFile runs successfully when the destination folder is a normal intenral path under the Cosmos VC, such as /my/ or /local/. However, when the destination folder is a path like /shares/bingads.algo.IntentMatching/Team/ or share folders to another VC, then the operation fails.

How can I resolve this issue?

Answer 1

Hi ,

Thanks for reaching out to Microsoft Q&A.

The issue seems to be related to permissions or the differences in how Azure Func App interacts with normal internal paths versus shared paths in Cosmos VC. Here are some steps to resolve the problem:

1. Check Cosmos VC Permissions

• Ensure that the Azure Function App identity (MI or Service Principal) has the required permissions to access the shared folders in Cosmos VC.
• Verify permissions explicitly for the paths where the operation fails. You might need to grant access to both read and write for the respective directories.

2. Validate Function App Credentials

• If the Azure Function App uses specific credentials to access Cosmos VC, ensure that these credentials have access to shared folders.
• Re-authenticate or re-validate the credentials to ensure they are up to date and have not expired.

3. Update ADF Linked Service Configuration

• If the Azure Function App is called as part of an ADF pipeline, ensure that the ADF pipeline's linked service or connection to Cosmos VC also has the necessary permissions to interact with shared folders.

4. Check Path Formatting

• Cosmos VC might have specific requirements for how paths to shared directories are structured.
• Ensure that the destination paths used for the shared folders are correctly formatted and compatible with the API or SDK that the Function App is using.

5. Investigate File or Path Locks

• Shared folders may sometimes have restrictions due to concurrent access or locks applied by other processes. Check if the target folder is locked or being used by another service.

6. Update Function Logic

• The CopySSFile function might have internal logic that handles standard paths but not shared paths. Review the function's code to ensure it can handle shared folder paths properly.
• You may need to adjust API calls or configuration within the function to support shared paths.

7. Enable Verbose Logging

• Turn on detailed logging for the Azure Function App to capture errors or issues when writing to shared folders.
• Check the Azure Monitor or Application Insights logs for any specific error messages.

8. Consult Cosmos VC Documentation

• Review the official Cosmos VC documentation to check for any restrictions or special requirements for accessing shared folders via external applications.

9. Test with a Direct API Call

• Try using a simple tool or script (e.g., Azure SDK or REST API) to manually perform a write operation to the problematic shared folders. This can help identify whether the issue is specific to the Azure Function App or a broader permission/configuration problem.

10. Consider Using a Proxy Service

• If the Function App cannot handle shared paths directly due to SDK or API limitations, consider creating a proxy service that can interface with Cosmos VC and handle both standard and shared paths uniformly.

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