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Concepts

The bucket holds secrets, but your role can only look.

Andrios Robert

• 1 min read

A proof of concept for AWS S3 read-only roles is a fast way to validate permissions before pushing changes into production. The goal: let approved identities list and get objects without any chance of overwriting, deleting, or adding new data. This protects critical files while giving users the visibility they need.

Step 1: Create the Read-Only IAM Policy
Define a policy with the minimum required actions. Use s3:GetObject and s3:ListBucket on the exact bucket ARN. For example:

{
 "Version": "2012-10-17",
 "Statement": [
 {
 "Effect": "Allow",
 "Action": [
 "s3:GetObject",
 "s3:ListBucket"
 ],
 "Resource": [
 "arn:aws:s3:::your-bucket-name",
 "arn:aws:s3:::your-bucket-name/*"
 ]
 }
 ]
}

Step 2: Attach Policy to a Role
Create a role in AWS IAM. Attach the read-only policy. Set the trusted entities to AWS services or cloud principals you expect to read data.

Step 3: Test the Role
Use the AWS CLI or SDK to assume the role. Run aws s3 ls s3://your-bucket-name and aws s3 cp s3://your-bucket-name/object-key ./local-file. Confirm that write operations fail with AccessDenied.

Step 4: Monitor Access Logs
Enable S3 server access logging or CloudTrail data events. This ensures visibility into who accessed which object, and when. Read-only doesn’t mean untracked—log everything.

Key AWS S3 Read-Only Role Benefits

  • Prevents accidental deletes or overwrites.
  • Limits blast radius in case of credential leaks.
  • Enables secure data sharing for audits, analytics, or reporting.
  • Quick proof of concept before full-scale access rollouts.

A strong proof of concept makes policy errors obvious early. Lock permissions down from the start. Validate them with targeted role tests, then ship only once you’re certain the S3 access model matches business intent.

See it live in minutes—build and verify AWS S3 read-only roles instantly at hoop.dev.

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