Move off deprecated GoogleCredential IAM authentication method to IAM credentials

[igouss]

Project should use this dependency instead for GCP IAM authentication
https://github.com/googleapis/google-auth-library-java

[mp911de]

Feel free to submit a pull request adding another variant of GcpIamAuthentication using the mentioned library.

[igouss]

Can you take a look?
https://github.com/spring-projects/spring-vault/compare/master...igouss:UpdateGcpCredentialSupplier?expand=1

I have trouble running tests locally. But I did not really try.

[INFO] Scanning for projects...
[ERROR] [ERROR] Some problems were encountered while processing the POMs:
[ERROR] Non-resolvable import POM: Could not find artifact org.springframework.vault:spring-vault-dependencies:pom:2.3.0-SNAPSHOT @ org.springframework.vault:spring-vault-parent:2.3.0-SNAPSHOT, /home/igoussev/spring-vault/pom.xml, line 108, column 16

One issue: see // TODO: Figure out how to set httpTransport on IamCredentialsClient

[igouss]

I found this warning while working on this. Sounds like this project will be affected.

https://cloud.google.com/iam/docs/migrating-to-credentials-api

The IAM API also contains methods for signing JWTs and binary blobs. As of July 1, 2020, these methods are deprecated in the REST API and in all client libraries for the IAM API. You must migrate to the Service Account Credentials API before July 1, 2021.

[mp911de]

This issue went unnoticed. Starting with a pull request is a good idea. Instead of changing the existing GcpIamAuthentication, I'd suggest to introduce a new variant to not break existing code.

[andreasgebauer]

Would be nice to have the support for the IAM credentials API available in the next release. I created a PR yesterday. Please let me know if this works for you

[mp911de]

Thanks a lot. Will have a look in the next few days.

[mp911de]

It makes sense to backport this change into the next service release given that the IAM API will stop working as of July this year.