Add support for token exchange login method

[bclouser]

Signed-off-by: Ben Clouser [email protected]

For your consideration...

I don't necessarily expect this to get merged as is. This API method requires a feature be enabled in keycloak to allow a token exchange... I am not sure what you do with features like this.

Additionally, since it requires a custom feature in keycloak, i didnt include the test i wrote, since it fails due to 501 (not implemented)

FWIW We use this feature in our keycloak service, so i figured I would try to upstream the feature 🤷

[Nerzal]

We could change the API of the function to expect the GrantType as parameter possibly?
Then it could be usable for more than only your custom function

[bclouser]

you know, looking at this a little more clearly, maybe this shouldnt even exist at all. If we make the grant-type customizable, we might as well just call client.GetToken() directly and pass in the TokenOptions{} ... and maybe that's what i should just do in my own code and forget about adding this function.

That being said, LoginClientTokenExchange() is a nice convenience function for future API users looking to retrieve a user's tokens via API, and prevents having to dig through keycloak docs to learn of the correct grant-type and oidc params.

I'd propose renaming the function to GetUserToken() though, as it's much more clear.

Thoughts?

[Nerzal]

LGTM, thanks for your contribution

[Nerzal]

Hi, thank you for your contribution, now merging.
The release of a new tag will take some more time, as the build pipelines are currently broken.