IAM SignBlob and SignJwt decommissioned.

[emmanuel-gcp]

Is your feature request related to a problem? Please describe.
I received a notification from GCP alerting that SignBlob and SignJwt will be decommissioned and this library still using it.
Describe the solution you'd like
The alert recommends the change
both authentication methods on:
https://iam.googleapis.com
Instead, it should use: https://iamcredentials.googleapis.com
Describe alternatives you've considered
since google will discontinue these methods I have considered look for another library or build a new one
Additional context
I'm using the class Signer which is the one that has a dependency on these endpoints.

[busunkim96]

Thanks for the heads up! It looks like we need to update the code in https://github.com/googleapis/google-auth-library-python/blob/37141e4dffc2ba3f3f57c5914544fb8b9cf7d017/google/auth/iam.py

Copying the text of the email for details:

Starting July 1, 2021, your calls to SignBlob and SignJwt (also known as JSON Web Tokens (JWT)) on the IAM API will no longer be supported and may fail. We are deprecating both authentication methods on https://iam.googleapis.com. You can now use https://iamcredentials.googleapis.com, instead.

You must migrate your projects off the IAM API to the new IAMCredentials API to avoid a service disruption. The IAMCredentials API supports higher traffic volumes across the network, giving you better access and reliability.

What do I need to know?

SignBlob and SignJwt are currently running and serving real-time traffic. You can migrate your projects at any time without a service disruption. Both methods have full replacements.

Notable syntactic and semantic differences between the old IAM API and the new IAMCredentials API include the following:

Request and response fields are slightly different.

New API doesn’t allow project-id in the resource name, and only allows a dash (-).

New API demands the expiration time (exp) field to be set in the JWT that is to be signed.

Review the migration guide and learn more about the differences between the old and new API.

What do I need to do?

Start using the new IAMCredentials API immediately. Follow these instructions to move your projects from the IAM API to the new IAMCredentials API before July 1, 2021.

For authentication details, refer to the IAM Credentials SignBlob API and IAM Credentials SignJwt API documentation.