Federation with AWS S3 Read-Only Roles

The request hit the terminal. S3 buckets filled with data, locked behind AWS permissions. You need federation with read-only roles—fast, precise, and secure.

AWS supports federated access to S3 through IAM roles tied to identity providers. The goal is clear: allow specific users or groups to read data, and nothing more. This means configuring trust relationships, scoped policies, and session controls that enforce strict limits.

Start with your identity provider—AWS IAM roles can integrate with providers via SAML or OIDC. Create a role that trusts the provider. In the trust policy, allow the federation principal. Limit permissions using an IAM policy granting only s3:GetObject and, if needed, s3:ListBucket. Avoid wildcard permissions. Point the policy to exact bucket ARNs and object prefixes.

Apply session duration constraints to limit how long access lasts—short windows reduce exposure. Configure the role’s trust relationship to require specific attributes or conditions from the identity provider. This can include user group tags or IP restrictions.

Test access using the AWS CLI or SDK with temporary credentials from the federated login. Run aws s3 ls s3://bucket-name to verify the scope. If the command returns only allowed paths and disallows writes, you’ve locked the role down properly.

Strong federation design for AWS S3 read-only roles prevents escalation and protects data from accidental or malicious modification. Use narrow permissions, precise trust policies, and continuous audit logging from AWS CloudTrail to verify compliance.

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