fix: Replace DefaultAzureCredential with ManagedIdentityCredential for production-safe authentication

[Prasanjeet-Microsoft]

Purpose

This pull request introduces a significant refactor to replace the usage of DefaultAzureCredential with a custom utility function get_azure_credential across the codebase. It also adds a new environment variable APP_ENV to differentiate between development and production environments. The most important changes are grouped below by theme.

Credential Management Refactor:

• Introduced get_azure_credential and get_azure_credential_async in azure_credential_utils.py to dynamically select between DefaultAzureCredential and ManagedIdentityCredential based on the APP_ENV environment variable ([code/backend/batch/utilities/helpers/azure_credential_utils.pyR1-R48](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-7da5073cced326c7dced13c0768484d67ae146b74dd907b44ebc20eb78bb9a7bR1-R48)).
• Replaced DefaultAzureCredential with get_azure_credential in multiple files, including database_factory.py, postgresdbservice.py, azure_blob_storage_client.py, azure_computer_vision_client.py, azure_form_recognizer_helper.py, azure_postgres_helper.py, azure_search_helper.py, env_helper.py, llm_helper.py, azure_search_datasource.py, azure_search_index.py, and azure_search_indexer.py ([[1]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-a92ad8584f19aec266f80fe1d5decb9f8603008378f3c9c9cca31dc1401b3e29L5-R5), [[2]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-a92ad8584f19aec266f80fe1d5decb9f8603008378f3c9c9cca31dc1401b3e29L28-R28), [[3]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-e7dfe35613384cb3374f9b90a8ec2f7effb9e3f09f6c693636cce07fa4904987L4-R4), [[4]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-e7dfe35613384cb3374f9b90a8ec2f7effb9e3f09f6c693636cce07fa4904987L24-R24), [[5]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-0501618008f86eacf193f09a72a1f5ec7bf348b4b19e5c937657d62e039a75f3L15-R15), [[6]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-0501618008f86eacf193f09a72a1f5ec7bf348b4b19e5c937657d62e039a75f3L28-R28), [[7]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-0501618008f86eacf193f09a72a1f5ec7bf348b4b19e5c937657d62e039a75f3L59-R59), [[8]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-b228a7a21f60cbc2f450086e1f8b430ab70df4579c1dae4c91dcc9d60477804fL3-R4), [[9]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-b228a7a21f60cbc2f450086e1f8b430ab70df4579c1dae4c91dcc9d60477804fL59-R60), [[10]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-c2f405722abb3fba86580c300caa1b9e14ea410594b11765a470cdbb703f5011L4-R4), [[11]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-c2f405722abb3fba86580c300caa1b9e14ea410594b11765a470cdbb703f5011L22-R22), [[12]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-50e3408b3f05e1cdccee7e3d8138209baebda958477121fe6a7e7c8289b89060L4-R4), [[13]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-50e3408b3f05e1cdccee7e3d8138209baebda958477121fe6a7e7c8289b89060L27-R27), [[14]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-8acbb6b44f9a1c4104fd339b585d57d8d628f8ceace3ccc6db9266b23c3106a7L5-R5), [[15]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-8acbb6b44f9a1c4104fd339b585d57d8d628f8ceace3ccc6db9266b23c3106a7L52-R55), [[16]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-8acbb6b44f9a1c4104fd339b585d57d8d628f8ceace3ccc6db9266b23c3106a7L64-R64), [[17]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-8acbb6b44f9a1c4104fd339b585d57d8d628f8ceace3ccc6db9266b23c3106a7L288-R288), [[18]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-7503275e90a545dba3519622ff9d0866a73e814ddbfbb61156137721bf2a6552L6-R7), [[19]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-7503275e90a545dba3519622ff9d0866a73e814ddbfbb61156137721bf2a6552L219-R220), [[20]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-7503275e90a545dba3519622ff9d0866a73e814ddbfbb61156137721bf2a6552L419-R420), [[21]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-7503275e90a545dba3519622ff9d0866a73e814ddbfbb61156137721bf2a6552L431-R432), [[22]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-43896759bad4bc2119807845cbb205a535d9caec19b671e07dcb6cfe73ec421aL11-R11), [[23]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-43896759bad4bc2119807845cbb205a535d9caec19b671e07dcb6cfe73ec421aL169-R169), [[24]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-191306cd0087ff3adec6be22022a25f09ad71cd8596aebb0050de612ec0b091eL10-R10), [[25]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-191306cd0087ff3adec6be22022a25f09ad71cd8596aebb0050de612ec0b091eL22-R22), [[26]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-9110c8709dac7271099ab02556bef8c9a110c6413badfff59eb0119c570d91a7L24-R24), [[27]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-9110c8709dac7271099ab02556bef8c9a110c6413badfff59eb0119c570d91a7L42-R42), [[28]](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-5a2966c08715e2d467100ebf3b4a58b5fc3a34159aee19f22c0341d50a929dfcL5-R5)).

Environment Configuration:

• Added a new APP_ENV variable to .env.sample to specify the application environment (e.g., dev or prod) ([.env.sampleR66-R67](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-088d9f35d23a4347d221d71dd49b02b95001dff4abe637a40fe0bc04d502049cR66-R67)).

Bug Fix:

• Fixed a typo in the environment variable name from SEMENTIC_KERNEL_SYSTEM_PROMPT to SEMANTIC_KERNEL_SYSTEM_PROMPT in env_helper.py ([code/backend/batch/utilities/helpers/env_helper.pyL364-R366](https://github.com/Azure-Samples/chat-with-your-data-solution-accelerator/pull/1872/files#diff-7503275e90a545dba3519622ff9d0866a73e814ddbfbb61156137721bf2a6552L364-R366)).

These changes improve the flexibility of credential management by supporting both development and production environments while maintaining security best practices.

Does this introduce a breaking change?

• Yes
• No

How to Test

• Get the code

git clone [repo-address]
cd [repo-name]
git checkout [branch-name]
npm install

What to Check

Verify that the following are valid:

• All usages of DefaultAzureCredential replaced
• Authentication logic tested locally or in a dev environment
• Regression tested (i.e., existing functionality relying on authentication continues to work)
• Confirmed no hardcoded secrets or fallback dev credentials remain