Token endpoints are hardcoded

[mauricehennig]

Describe the issue

The Teams SDK currently uses hardcoded URLs for BotFramework token exchange.
For example here:

teams.net/Libraries/Microsoft.Teams.Api/Clients/UserTokenClient.cs

Line 41 in 12758cc

var req = HttpRequest.Get($"https://token.botframework.com/api/usertoken/GetToken?{query}");

This makes it impossible to use other endpoints e.g. the european endpoints which are documented here: https://learn.microsoft.com/en-us/azure/bot-service/ref-oauth-redirect-urls?view=azure-bot-service-4.0

As a result, it is not possible for the bot backend to obtain a user token from botframework because the request is failing.

Expected behavior

The SDK should allow consumers to configure or override default endpoint URLs via:

• Environment variables
  or
• Configuration options during initialization
  or
• A documented override mechanism

Actual behavior

The URLs are currently hardcoded to https://token.botframework.com and cannot be changed without modifying the SDK source.

Suggested fix

Introduce configuration options to override default endpoint URLs. For example:

BOTFRAMEWORK_BASE_URL=https://europe.token.botframework.com

[corinagum]

Related to: microsoft/teams.ts#367

[Benjiiim]

What about introducing more environment variables to set the bot service location ("global", "westeurope", ...) in the azurebot.bicep file, to set the token service URL in the validDomains section of the app manifest, to set the right OAuth Redirect URL in the aad.manifest.json file, and maybe more (eg: europe.api.botframework.com might be required somewhere as well).