[Storage] Investigate OAuth2 scopes for storage clients

[jeremymeng]

Currently we use a scope of https://storage.azure.com/.default for storage clients

example: https://github.com/azure/azure-sdk-for-js/blob/feature%2Fstorage/sdk/storage/storage-blob/src/Pipeline.ts#L232

Is it possible to have other scopes (e.g., for different Azure stack).

[jeremymeng]

It probably should be an array of strings that users can customize.

[XiaoningLiu]

@jeremymeng Link seems broken "https://github.com/azure/azure-sdk-for-js/blob/feature%2Fstorage/sdk/storage/storage-blob/src/Pipeline.ts#L232".

Why scope value has to be defined in storage SDK?

[jeremymeng]

@XiaoningLiu It was moved to

azure-sdk-for-js/sdk/storage/storage-blob/src/utils/constants.ts

Line 12 in 21ecc3f

export const DefaultStorageScope: string = "https://storage.azure.com/.default";

. It looks specific to storage. I saw some sample C# code that has it as a string array.

[jeremymeng]

I was thinking that there might be other possible values for the scope. If not we can close this issue.

[XiaoningLiu]

I'm thinking scope variables should be provided by customer when creating token credentials. Is this limitation from @azure/identity?

    if (!isAnonymousCreds) {
      factories[2] = isTokenCredential(credential)	      factories[2] = isTokenCredential(credential)
        ? bearerTokenAuthenticationPolicy(credential, "https://storage.azure.com/.default")	        ? bearerTokenAuthenticationPolicy(credential, DefaultStorageScope)
        : credential;	        : credential;
    }	    }

[jeremymeng]

I'm thinking scope variables should be provided by customer when creating token credentials. Is this limitation from @azure/identity?

@daviwil do you have more insights?

[jeremymeng]

@XiaoningLiu In the future we might provide a global preset of known default settings in @azure/identity to be used by various SDK libraries. At this point it is better to have a option on the client to specify the default one for storage and allow customization later.