In today’s cloud-driven world, identity federation simplifies authentication across various platforms. For organizations leveraging multiple cloud services, integrating a single sign-on (SSO) solution, such as Google as an identity provider, can streamline user management and security protocols. This blog post will guide you through utilizing Google as an Identity Provider (IdP) for AWS, including setup, authentication, and leveraging temporary AWS credentials.

Introduction to AWS Identity Federation

AWS Identity Federation allows external identities, such as those from Google, to access AWS services without creating separate AWS Identity and Access Management (IAM) users. This is achieved by trusting an external identity provider, allowing users to sign in once and access both Google and AWS services. The integration simplifies credential management and enhances security by reducing the number of separate login systems.

Identity federation with AWS can be implemented using Security Token Service (STS), which issues temporary credentials for accessing AWS resources based on the user’s identity token obtained from Google.

Setting Up Google as an Identity Provider

To configure Google as an identity provider in AWS, follow these steps:

  1. Create a Google API Console Project: Log into the Google Cloud Console, create a new project, and enable the Google Identity service.
  2. Configure OAuth Consent Screen: Set up the OAuth consent screen in Google Console, providing basic app details like app name, email, and domain. Add necessary scopes for authentication.
  3. Create OAuth 2.0 Credentials: Generate OAuth 2.0 client credentials in Google Console. Note the Client ID and Client Secret, which are essential for later steps.
  4. Configure AWS as a Service Provider (SP): Configure the identity provider in AWS IAM by adding Google as an external IdP. Use the Client ID and Client Secret obtained earlier to complete the connection.
  5. Create an IAM Role for Federated Users: Create an IAM role with policies that grant federated users access to specific AWS services.

Authenticating Users with Google and Capturing Identity Tokens

Once Google is set up as an IdP, users can authenticate via Google, and the identity tokens will be used to obtain temporary credentials for AWS access. Here’s a step-by-step process:

  1. User Logs In via Google: When users attempt to log in to your app, redirect them to the Google sign-in page.
  2. Capture Identity Token: Once authenticated, Google returns an identity token (JWT), which includes user information like email and a unique identifier. This token will be exchanged for AWS credentials.

Obtaining Temporary AWS Credentials Using STS

AWS Security Token Service (STS) enables the exchange of Google’s identity token for temporary AWS credentials. Here’s how it works:

  1. Invoke the AssumeRoleWithWebIdentity API: Using the identity token captured from Google, invoke AWS STS’s AssumeRoleWithWebIdentity API to assume the IAM role you configured for federated access.
  2. Retrieve Temporary Credentials: The response includes temporary security credentials (Access Key, Secret Access Key, and Session Token) that users can use to interact with AWS services.

Example Code Snippet:

aws sts assume-role-with-web-identity \

    –role-arn “arn:aws:iam::123456789012:role/WebIdentityRole” \

    –role-session-name “GoogleFederationSession” \

    –web-identity-token $IDENTITY_TOKEN \

    –duration-seconds 3600

Interacting with AWS Services Using Temporary Credentials

With temporary credentials, the user can interact with AWS services based on the permissions attached to the IAM role. These credentials typically expire after an hour, providing a secure and limited-time window for access.

For example, users who want to access an S3 bucket can configure the AWS CLI or SDK with their temporary credentials and make the appropriate API calls.

aws s3 ls –region us-west-2

This process ensures that users authenticated through Google have limited and secure access to AWS services without the need to manage long-term IAM credentials.

Summary: Benefits and Best Practices of AWS Identity Federation

Utilizing Google as an identity provider for AWS offers several key benefits:

  • Enhanced Security: Reducing the need for multiple sets of credentials minimizes the risk of account compromise. Google’s secure OAuth 2.0 authentication system adds another layer of protection.
  • Simplified User Management: Organizations can manage user identities from a centralized Google Workspace, which eases onboarding and access control processes.
  • Temporary Credentials: STS issues time-limited credentials, which minimize exposure to long-term access keys and enhance security.
  • Reduced Administrative Overhead: Identity federation minimizes the number of credentials and roles that need to be manually managed in AWS.

Best Practices:

  • Use Least Privilege: Ensure that IAM roles for federated access follow the principle of least privilege by only granting necessary permissions.
  • Monitor and Rotate OAuth Credentials: To prevent security vulnerabilities, regularly review and rotate the Google OAuth credentials used in AWS.
  • Enable MFA: To add security, implement multi-factor authentication (MFA) for Google accounts, further safeguarding AWS access.
  • Audit Access Logs: Leverage AWS CloudTrail to monitor and audit federated access patterns, ensuring only authorized users interact with AWS resources.

References

How to use Google Workspace as an external identity provider for AWS IAM Identity Center

Access AWS using a Google Cloud Platform native workload identity