Verify Permissions for ROSA STS Deployment
Authors:
Tyler Stacey,
Kumudu Herath
Last Editor:
Dustin Scott
Published Date:
4 October 2022
Modified Date: 25 May 2023
To proceed with the deployment of a ROSA cluster, an account must support the required roles and permissions. AWS Service Control Policies (SCPs) cannot block the API calls made by the installer or operator roles.
Details about the IAM resources required for an STS-enabled installation of ROSA can be found here: https://docs.openshift.com/rosa/rosa_architecture/rosa-sts-about-iam-resources.html
This guide is validated for ROSA v4.11.X.
Prerequisites
Verify ROSA Permissions
To verify the permissions required for ROSA we can run the script below without ever creating any AWS resources.
The script uses the rosa, aws, and jq CLI commands to create files in the working directory that will be used to verify permissions in the account connected to the current AWS configuration.
The AWS Policy Simulator is used to verify the permissions of each role policy against the API calls extracted by jq; results are then stored in a text file appended with .results.
This script will verify the permissions for the current account and region.
#!/bin/bash
while getopts 'p:' OPTION; do
case "$OPTION" in
p)
PREFIX="$OPTARG"
;;
?)
echo "script usage: $(basename \$0) [-p PREFIX]" >&2
exit 1
;;
esac
done
shift "$(($OPTIND -1))"
rosa create account-roles --mode manual --prefix $PREFIX
INSTALLER_POLICY=$(cat sts_installer_permission_policy.json | jq )
CONTROL_PLANE_POLICY=$(cat sts_instance_controlplane_permission_policy.json | jq)
WORKER_POLICY=$(cat sts_instance_worker_permission_policy.json | jq)
SUPPORT_POLICY=$(cat sts_support_permission_policy.json | jq)
simulatePolicy () {
outputFile="${2}.results"
echo $2
aws iam simulate-custom-policy --policy-input-list "$1" --action-names $(jq '.Statement | map(select(.Effect == "Allow"))[].Action | if type == "string" then . else .[] end' "$2" -r) --output text > $outputFile
}
simulatePolicy "$INSTALLER_POLICY" "sts_installer_permission_policy.json"
simulatePolicy "$CONTROL_PLANE_POLICY" "sts_instance_controlplane_permission_policy.json"
simulatePolicy "$WORKER_POLICY" "sts_instance_worker_permission_policy.json"
simulatePolicy "$SUPPORT_POLICY" "sts_support_permission_policy.json"
Usage Instructions
To use the script, run the following commands in a bash terminal (the -p option defines a prefix for the roles):
mkdir scratch
cd scratch
curl https://raw.githubusercontent.com/rh-mobb/documentation/main/content/docs/rosa/verify-permissions/verify-permissions.sh --output verify-permissions.sh
chmod +x verify-permissions.sh
./verify-permissions.sh -p SimPolTest
After the script completes, review each results file to ensure that none of the required API calls are blocked:
$ cat sts_support_permission_policy.json.results
EVALUATIONRESULTS cloudtrail:DescribeTrails allowed *
MATCHEDSTATEMENTS PolicyInputList.1 IAM Policy
ENDPOSITION 6 159
STARTPOSITION 17 3
EVALUATIONRESULTS cloudtrail:LookupEvents allowed *
MATCHEDSTATEMENTS PolicyInputList.1 IAM Policy
ENDPOSITION 6 159
STARTPOSITION 17 3
EVALUATIONRESULTS cloudwatch:GetMetricData allowed *
MATCHEDSTATEMENTS PolicyInputList.1 IAM Policy
ENDPOSITION 6 159
STARTPOSITION 17 3
...
If any actions are blocked, review the error provided by AWS and consult with your Administrator to determine if SCPs are blocking the required API calls.