Managing Google Cloud Authentication with 'gcloud auth' (with examples)

The gcloud auth command is an essential part of the Google Cloud SDK, allowing users to manage authentication credentials for accessing Google Cloud resources. Through this command, users can grant or revoke authorization for the Google Cloud CLI (gcloud), manage credentials, and interact with cloud accounts seamlessly. Below, we explore various use cases for gcloud auth with detailed examples.

Use case 1: Authorize Google Cloud access for the gcloud CLI with Google Cloud user credentials and set the current account as active

Code:

gcloud auth login

Motivation: Using gcloud auth login is the first step for anyone wishing to interact with Google Cloud services through the command line. When you run this command, it opens a browser window prompting you to sign in with your Google account. This command is perfect for users who need to perform tasks across different Google Cloud projects or resources using their personal or organizational Google account.

Explanation:

• gcloud: This is the command-line interface tool for interacting with Google Cloud. It allows for a wide range of functionalities, including authentication, configuration, and management.
• auth: This component deals with authentication, giving users the tools to manage how they are verified and authorized within Google Cloud.
• login: This command specifically asks for authentication using a web-based login, associating your Google account with the gcloud CLI.

Example Output: Upon running this command, a new browser tab will open for Google’s authentication page. After successful login, you should see a confirmation similar to:

You are now logged in as [your-email@example.com].
Your current project is [None]. You can change this setting by running:
  $ gcloud config set project PROJECT_ID

Use case 2: Authorize Google Cloud access similar to gcloud auth login but with service account credentials

Code:

gcloud auth activate-service-account --key-file=/path/to/key-file.json

Motivation: This use case is vital for automated systems or scripts that need consistent access to Google Cloud resources. Instead of relying on user-based login, service accounts provide a way for applications or virtual machines to authenticate and access resources securely. It’s particularly useful in production environments where human interaction should be minimized for security and reliability.

Explanation:

• gcloud: As before, this signifies the usage of the Google Cloud command-line tool.
• auth: Pertaining to authentication.
• activate-service-account: This command sets up service account credentials for use with the gcloud command and API calls.
• --key-file=/path/to/key-file.json: This argument specifies the path to a JSON file that contains the service account key. The key file is a vital component, containing credentials necessary for the service account to identify itself and authenticate.

Example Output: On executing this command, you will see a confirmation that the service account is activated:

Activated service account credentials for: [service-account-email@project-id.iam.gserviceaccount.com]

Use case 3: Manage Application Default Credentials (ADC) for Cloud Client Libraries

Code:

gcloud auth application-default login

Motivation: Application Default Credentials (ADC) are crucial for developers working with Google Cloud Client Libraries. By configuring ADC, developers can ensure that their applications correctly authenticate and authorize against Google Cloud services without manual intervention or complex setups. This simplifies the development process when collaborating across systems or environments.

Explanation:

• gcloud: Indicating usage of Google Cloud CLI.
• auth: Deals with setting up authentication.
• application-default: Focuses on managing default application credentials, which are used by various clients and libraries to authenticate service usage.
• login: Initiates the process of setting up ADC through a web-based user login flow.

Example Output: Executing this command opens a browser window, and following successful login, results in:

Credentials saved to file: [/home/user/.config/gcloud/application_default_credentials.json]
These credentials will be used by any library supporting Application Default Credentials.

Use case 4: Display a list of Google Cloud accounts currently authenticated on your system

Code:

gcloud auth list

Motivation: When managing multiple Google Cloud accounts, it’s crucial to have a clear overview of which accounts are currently authenticated on your system. This command helps users switch between accounts seamlessly and ensures tasks are performed under the correct account, thereby adhering to organizational policies and ensuring security compliance.

Explanation:

• gcloud: Relates to the Google Cloud SDK tool.
• auth: pertains to the authentication processes.
• list: Requests a listing of all accounts currently authenticated against the Google Cloud CLI on your system.

Example Output: Running this command yields a list summarizing all user accounts configured for gcloud:

Credentialed Accounts:
 - [first-account@example.com]
 - [second-account@example.com] *(active)*

Use case 5: Display the current account’s access token

Code:

gcloud auth print-access-token

Motivation: Access tokens are essential for making authenticated requests to Google Cloud services. This command allows users to retrieve the current active account’s access token, which can then be used in APIs or scripts demanding temporary explicit authentication. It’s particularly useful in debugging or integrating with non-Google tools that require Google Cloud access tokens.

Explanation:

• gcloud: The main tool in the Google Cloud SDK.
• auth: Concerning authentication tasks.
• print-access-token: Outputs the current active account’s access token to the terminal, allowing it to be used elsewhere as needed.

Example Output: Upon execution, the command outputs a token string:

ya29.c.KqgB1oZ7m4mXe_3xHkRR-sveEfJxzL6... (truncated)

Use case 6: Remove access credentials for an account

Code:

gcloud auth revoke [ACCOUNT]

Motivation: Security best practices often necessitate the removal of credentials that are no longer needed, perhaps due to role changes or the conclusion of a project. Revoking access for a specific account prevents unauthorized access and ensures better credential hygiene. This command is crucial for maintaining the security posture of an organization’s cloud presence.

Explanation:

• gcloud: Google Cloud’s command-line tool.
• auth: Related to the authentication aspect.
• revoke: Indicates the action of removing authentication credentials.
• [ACCOUNT]: This represents the specific Google account from which to revoke access. It is replaced with the email address of the account in question.

Example Output: After executing this command, the specified account’s credentials are removed:

Revoked credentials for: [revoked-account@example.com]

Conclusion:

The gcloud auth command provides robust options for authenticating and managing access credentials in Google Cloud environments. Whether managing user or service account access, switching between accounts, or ensuring credentials remain current, gcloud auth plays an essential role in cloud administration and security. Each use case, from setting up application default credentials to revoking access, exemplifies vital steps in efficient cloud resource management.