Write IAM Policies with Least Privilege Actions
Scope the IAM policy to exact actions and resources so a leaked key can only read one bucket not the whole account.
Task
Configure aws iam put-role-policy --policy-document file://least-privilege.json so the cloud resource enforces the control automatically without manual console steps.
When to use this
An audit finds that aws iam put-role-policy --policy-document file://least-privilege.json was configured manually and drifted, leaving a resource exposed for two weeks.
Prerequisites
- Terraform or IaC tooling installed
- Cloud provider credentials with target permissions
Steps
1. Configure aws iam put-role-policy --policy-document file://least-privilege.json in the project configuration file with the recommended defaults.
aws iam put-role-policy --policy-document file://least-privilege.json
Expected output: The configuration is accepted and aws iam put-role-policy --policy-document file://least-privilege.json runs without errors on the first invocation.
2. Run the check locally to verify aws iam put-role-policy --policy-document file://least-privilege.json produces the expected result before pushing.
pnpm test
Expected output: Local run matches CI behavior; no surprises after push.
3. Add the gate to the CI pipeline so aws iam put-role-policy --policy-document file://least-privilege.json blocks merge on failure.
- name: Run add iam least privilege policy
run: pnpm test
Expected output: Pull requests with failing aws iam put-role-policy --policy-document file://least-privilege.json are blocked from merging.
Troubleshooting
Problem
The check passes locally but fails in CI
Solution
Pin dependency versions and the runtime to match CI exactly; reproduce with the same Docker image or act.
Problem
Configuration is rejected with a schema error
Solution
Check the tool version matches the config schema; older versions may not support newer fields.
Limitations
- The gate only runs on events that trigger the workflow; locally pushed commits bypass it.
- Configuration drift is possible if someone edits settings outside version control.
Codify the control
Start by measuring the problem. Scope the IAM policy to exact actions and resources so a leaked key can only read one bucket not the whole account. The most common mistake is adding the gate without first confirming it catches the issue you care about. Run aws iam put-role-policy –policy-document file://least-privilege.json against the current codebase and inspect the output before wiring it into CI.
aws iam put-role-policy --policy-document file://least-privilege.jsonDetect drift
Once the gate is in place, make failures actionable. A failing aws iam put-role-policy –policy-document file://least-privilege.json should point to the exact file and line, not a generic error. Pin the tool version in the lockfile so a upstream release does not silently change behavior. Review the gate output in every pull request just like a test result.