google: Provide method to retrieve project ID configured on gcloud

[ahmetb]

(moved from googleapis/google-cloud-go#707)

It looks like Go client libraries do not provide a method do to this. I've been shelling out to gcloud myself but not sure what's the way guaranteed to work. It would be great if this library can provide a method that will keep working.

On a side note, when I use the FindCredentials() method on my dev machine, which has ADC enabled with gcloud auth application-default login, the ProjectID field of DefaultCredentials comes as empty string.

Looks like other Google Cloud libraries are using the following commands:

• gcloud config config-helper --format json
• gcloud -q config list core/project --format=json

Examples:

• Python: https://github.com/GoogleCloudPlatform/google-auth-library-python/blob/d020426e170d9d8ab5f9d8d37626c278fed4770c/google/auth/_cloud_sdk.py#L111-L133

• Node.js: https://github.com/google/google-auth-library-nodejs/blob/bd13376281a3af6e73fb729ea867950739c3c899/ts/lib/auth/googleauth.ts#L157-L160

[rakyll]

/cc @zombiezen

[vsimon]

Friendly bump, also seeing when we use FindDefaultCredentials() method on a local dev machine, the ProjectID field of DefaultCredentials comes as empty string.

[zombiezen]

The behavior of FindDefaultCredentials is working as intended here: the ProjectID field of Credentials is the project ID of the role. User-level credentials do not have an associated project.

Shelling out to gcloud in the manner described above doesn't seem unreasonable to ask someone to do to obtain the project ID information from gcloud. Typically project ID is passed along to an application via environment variable or command-line flag, not obtained from the gcloud CLI.

/cc @deKlerk

[Sytten]

Bump, I also think there should be a way to retrieve the project ID in local like you can with other languages. This is quite annoying for some instances like secrets that require the project ID to be set.

[pwen]

Bump as well.

[arikkfir]

I think it's not unreasonable to ask that "Application Default Credentials" would include a project ID. Almost every GCP API requires (and almost every resource is associated with) a project, so having a default project seems to fit the bill here.

Once we agree on that, I think it becomes a no-brainer that the application default credentials Go SDK API would provide that project ID as well.

I think it's also self-evident that the FindDefaultCredentials method returns a Credentials object, which includes a ProjectID - sounds like this was in someone's mind all along anyway, and even if not - sounds to me (and I'm sure to almost every other GCP developer out there) to be a reasonable choice.