sdk/azcore: TokenCredential should not be internal

[ItalyPaleAle]

Bug Report

In sdk/azcore, the TokenCredential interface, as well as related structs such as TokenRequestOptions are in an internal package and cannot be used by third-party code.

We are working with APIs that are not supported by the SDKs yet, including some that have no roadmap to be supported. In order to interact with them, we need to retrieve access tokens. Because the TokenRequestOptions is internal, we cannot invoke GetToken on an azcore.TokenCredential object and retrieve an access token. Thus, we cannot make API calls without having to also re-implement the entire auth flow.

• import path of package in question, e.g. sdk/azcore
• SDK version e.g. 0.23.0
• output of go version: go version go1.18 linux/amd64

[chlowell]

TokenCredential and TokenRequestOptions are exported, though from different packages, so it's possible to implement custom credential types and acquire a token from any credential type in azidentity:

package main

import (
    "context"

    "github.com/Azure/azure-sdk-for-go/sdk/azcore"
    "github.com/Azure/azure-sdk-for-go/sdk/azcore/policy"
    "github.com/Azure/azure-sdk-for-go/sdk/azidentity"
)

// implementing TokenCredential
type CustomCredential struct {}

func (c *CustomCredential) GetToken(ctx context.Context, options policy.TokenRequestOptions) (*azcore.AccessToken, error) {
	return nil, nil
}

var _ azcore.TokenCredential = (*CustomCredential)(nil)

// calling GetToken()
func main() {
	cred, err := azidentity.NewDefaultAzureCredential(nil)
	if err != nil {
		panic(err)
	}
	tk, err := cred.GetToken(
		context.TODO(), policy.TokenRequestOptions{Scopes: []string{"https://management.azure.com/.default"}},
	)
	if err != nil {
		panic(err)
	}
}

[ghost]

Hi @ItalyPaleAle. Thank you for opening this issue and giving us the opportunity to assist. We believe that this has been addressed. If you feel that further discussion is needed, please add a comment with the text “/unresolve” to remove the “issue-addressed” label and continue the conversation.

[ghost]

Hi @ItalyPaleAle. Thank you for opening this issue and giving us the opportunity to assist. We believe that this has been addressed. If you feel that further discussion is needed, please add a comment with the text “/unresolve” to remove the “issue-addressed” label and continue the conversation.

[ItalyPaleAle]

Thanks for the explanation. I'll take a look at that and will let you know if I run into any issue.

[jhendrixMSFT]

For some additional context, there are two reasons why we have internal types that are exported via type aliases.

• To break cyclic dependencies.
• To offer a type in one package (e.g. azcore) but its usage in another (e.g. runtime).

I've refactored the internal content that's actually exported under an internal/exported package to make it clear. In this process, it was discovered that we didn't actually need to do this with TokenCredential and its related types, so those are now defined in the packages from where they're exported.

[ghost]

Hi @ItalyPaleAle, since you haven’t asked that we “/unresolve” the issue, we’ll close this out. If you believe further discussion is needed, please add a comment “/unresolve” to reopen the issue.