Image section

(Required) Defines the operating system for the cluster.

Image:
  Os: string
  CustomAmi: string

Image properties

Os (Required, String)

Specifies the operating system to use for the cluster. The supported values are alinux2, centos7, ubuntu1804, and ubuntu2004.

Other than the specific AWS Regions mentioned in the following table that don't support centos7. All other AWS commercial Regions support all of the following operating systems.

Partition (AWS Regions)	alinux2	centos7	ubuntu1804 and ubuntu2004
Commercial (All AWS Regions not specifically mentioned)	True	True	True
AWS GovCloud (US-East) (us-gov-east-1)	True	False	True
AWS GovCloud (US-West) (us-gov-west-1)	True	False	True
China (Beijing) (cn-north-1)	True	False	True
China (Ningxia) (cn-northwest-1)	True	False	True

Update policy: If this setting is changed, the update is not allowed.

CustomAmi (Optional, String)

Specifies the ID of a custom AMI to use for the head and compute nodes instead of the default AMI. For more information, see AWS ParallelCluster AMI customization.

If the custom AMI requires additional permissions for its launch, these permissions must be added to both the user and head node policies.

For example, if a custom AMI has an encrypted snapshot associated with it, the following additional policies are required in both the user and head node policies:

{
   "Version": "2012-10-17",
   "Statement": [
       {
           "Effect": "Allow",
           "Action": [
               "kms:DescribeKey",
               "kms:ReEncrypt*",
               "kms:CreateGrant",
               "kms:Decrypt"
           ],
           "Resource": [
               "arn:aws:kms:<AWS_REGION>:<AWS_ACCOUNT_ID>:key/<AWS_KMS_KEY_ID>"
           ]                                                    
       }
   ]
}

To troubleshoot custom AMI validation warnings, see Troubleshooting custom AMI issues.

Update policy: If this setting is changed, the update is not allowed.