bug: azdls backend doesn't load Azure credentials from environment variables

[rohankmr414]

Describe the bug

The azdls backend does not load Azure credentials from environment variables, unlike the azblob backend. Specifically, it's not calling AzureStorageConfig::default().from_env(), which means Azure Workload Identity environment variables are never loaded.

This causes authentication to fail in environments like Azure Kubernetes Service (AKS) with Workload Identity enabled, where credentials are provided via environment variables rather than explicit configuration.

Steps to Reproduce

1. Deploy an application using the azdls backend in AKS with Workload Identity enabled
2. Set up the following environment variables (automatically injected by Azure Workload Identity):
   • AZURE_FEDERATED_TOKEN_FILE
   • AZURE_CLIENT_ID
   • AZURE_TENANT_ID
   • AZURE_AUTHORITY_HOST
3. Try to access Azure Data Lake Storage Gen2 without explicitly configuring credentials in code
4. Authentication fails and falls back to IMDS, which doesn't work in AKS

Expected Behavior

The azdls backend should automatically load Azure credentials from environment variables, just like the azblob backend does (as implemented in PR #4705).

Additional Context

PR #4705 fixed this issue for the azblob backend to close #4704, but the same fix was not applied to the azdls backend. The two backends should have consistent behavior for credential loading.

Are you willing to submit a PR to fix this bug?

• Yes, I would like to submit a PR.

[dosubot]

Thanks for the detailed bug report! I can confirm this issue — the azdls backend is indeed missing the from_env() call that azblob has.

The difference:

• azblob correctly starts with AzureStorageConfig::default().from_env() and then overrides with explicit config values
• azdls creates the config directly without loading environment variables first

Interestingly, the azdls documentation states "OpenDAL will try load credential from the env" — but the code doesn't actually implement this.

The fix should follow the azblob pattern: start with AzureStorageConfig::default().from_env() then override with any explicitly configured values. Since you've indicated you'd like to submit a PR, that pattern should be straightforward to replicate!

To reply, just mention @dosu.

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