gcloud-auth

Authorize Google Cloud access for the gcloud CLI with Google Cloud user credentials and set the current account as active

$ gcloud auth login

$ gcloud auth activate-service-account

$ gcloud auth application-default

$ gcloud auth list

$ gcloud auth print-access-token

$ gcloud auth revoke

gcloud auth SUBCOMMAND [GLOBAL_OPTIONS]

login
    Authenticates the gcloud CLI with user credentials via a web browser flow.

activate-service-account
    Authenticates using a service account key file, typically for automated environments.

list
    Lists all authenticated accounts and indicates the currently active one.

print-access-token
    Prints the access token for the currently active account to standard output.

application-default login
    Authenticates for Application Default Credentials (ADC) using user credentials.

revoke
    Revokes access credentials for specified authenticated accounts, logging them out.

configure-docker
    Configures Docker to use gcloud credentials for authenticating to Google Container Registry (GCR) or Artifact Registry.

--project=[PROJECT_ID]
    A global option specifying the Google Cloud project for the command to operate within.

--account=[ACCOUNT]
    A global option specifying which authenticated account to use for the command.

--quiet | -q
    A global option that disables interactive prompts for non-destructive commands.

--format=[FORMAT]
    A global option setting the output format of the command (e.g., json, text, yaml).

The gcloud auth command is a crucial component of the Google Cloud SDK, designed to manage authentication to Google Cloud APIs and resources. It provides a comprehensive set of subcommands to handle various authentication methods, including user accounts, service accounts, and Application Default Credentials (ADC). Users commonly employ gcloud auth login for interactive browser-based authentication, while gcloud auth activate-service-account is utilized for non-interactive scenarios, such as in CI/CD pipelines or virtual machines, by leveraging service account key files. The command also facilitates listing active accounts, revoking credentials, and printing access tokens for direct API interactions. Proper use of gcloud auth ensures secure and authorized access to Google Cloud services like Compute Engine, Cloud Storage, and BigQuery. It serves as the primary interface for configuring the SDK's credentials, enabling the gcloud CLI to interact with your cloud projects effectively.

Credential Security: Service account key files grant powerful access and must be handled with extreme care. Avoid committing them to version control systems.
Token Expiration: Access tokens obtained are temporary but are automatically refreshed by the SDK. However, long-lived service account keys should be rotated periodically for security.
Application Default Credentials (ADC): Be aware of the ADC lookup order. Using gcloud auth application-default login can set user credentials as ADC, potentially overriding other service account credentials in an environment.
Permissions: The authenticated account or service account requires appropriate IAM roles and permissions to perform actions on Google Cloud resources. Insufficient permissions will result in 'Permission Denied' errors.
Multiple Accounts: While gcloud auth list shows multiple accounts, only one can be active at a time for general gcloud commands unless explicitly specified with the --account flag per command.

For interactive user access, gcloud auth login is the standard method, providing a seamless browser-based authentication experience. For automated processes, such as CI/CD pipelines or scripts running outside Google Cloud infrastructure, using gcloud auth activate-service-account with a service account key file is a common practice. However, when running applications or services directly on Google Cloud infrastructure (e.g., Compute Engine, Cloud Run, GKE), leveraging the instance's built-in service account via the metadata service is the most secure and recommended approach, as it eliminates the need to manage sensitive key files.

When authenticating, especially with gcloud auth login, the permissions granted are often tied to OAuth 2.0 scopes. For instance, a broad scope like https://www.googleapis.com/auth/cloud-platform grants extensive access. While gcloud typically handles the necessary scopes automatically for its commands, understanding scopes is critical for developing custom applications and for fine-tuning security permissions, as they define the specific set of resources and actions an authenticated principal is allowed to perform.

The gcloud auth command is a fundamental part of the Google Cloud SDK, which has undergone continuous evolution since its initial release. Its development has paralleled the rapid expansion of Google Cloud services, leading to a unified and flexible authentication interface that consolidates various underlying methods. Historically, authentication to Google Cloud APIs involved disparate approaches. gcloud auth streamlined this process, providing robust support for user accounts, service accounts, and more recently, advanced features like Workload Identity federation. The command's evolution also reflects Google's emphasis on Application Default Credentials (ADC) as a preferred authentication strategy for applications, making gcloud auth application-default login a key entry point for developers. Its ongoing refinement ensures secure, efficient, and user-friendly access to Google Cloud resources.

gcloud config(1), gcloud projects(1), gsutil(1), kubectl(1), docker(1)