[Feature Request] Region auto enable on env variable

[bgavrilMS]

Region auto-enable

1. On creation of a ConfidentialClientApplication, MSAL shall detect env variable MSAL_FORCE_REGION, which will be set to a specific region (e.g. westus1)
2. If this env variable is set, MSAL shall opt-in to ESTS-R with the value of this variable.

Disabling the behavior

If region is explicitly set in MSAL to the string "DisableMsalForceRegion`, then the above no longer applies

Conflicts with WithAzureRegion(xyz)

Use of the api WithRegion(xyz) takes precedence over the env variable.

Acceptance tests

For all of the tests, assume env variable MSAL_FORCE_REGION=eastus

1. No other config is used. ACTUAL region used: eastus
2. App developer configures region "westus" in MSAL. ACTUAL region used: westus
3. App developer configures region "DisableMsalForceRegion" in MSAL. ACTUAL region used: none

Alternatives

No response

[weinong]

It already does, no?
https://review.learn.microsoft.com/en-us/identity/microsoft-identity-platform/msal-net-regional-adoption?branch=main#providing-a-region-with-azureidentity

[bgavrilMS]

It already does, no? https://review.learn.microsoft.com/en-us/identity/microsoft-identity-platform/msal-net-regional-adoption?branch=main#providing-a-region-with-azureidentity

No. Today app developers must explicitly opt-in to ESTS-R by using the API WithAzureRegion(string). They can either inject the region name directly, or they can use "TryAutoDetect" and MSAL has an algorithm to detect the region.

This proposal is for MSAL to auto-detect an env var, eliminating the need for app developer to use WithAzureRegion API.

[rayluo]

This proposal is for MSAL to auto-detect an env var, eliminating the need for app developer to use WithAzureRegion API.

This line shall be inserted into the very beginning of this feature description as a "Problem Statement" or a "WHY". :-)

Disabling the behavior

If region is explicitly set in MSAL to the string "DisableMsalForceRegion`, then the above no longer applies

Why do we need this special case? Wouldn't it be much more intuitive (and easier to implement) to do "if the env var MSAL_FORCE_REGION is absent or empty, then the above no longer applies"?