Using service-linked roles for Systems Manager
Amazon Systems Manager uses Amazon Identity and Access Management (IAM) service-linked roles. A service-linked role is a unique type of IAM role that is linked directly to Systems Manager. Service-linked roles are predefined by Systems Manager and include all the permissions that the service requires to call other Amazon Web Services on your behalf.
Note
A service role role differs from a service-linked role. A service role is a type of Amazon Identity and Access Management (IAM) role that grants permissions to an Amazon Web Service so that the service can access Amazon resources. Only a few Systems Manager scenarios require a service role. When you create a service role for Systems Manager, you choose the permissions to grant so that it can access or interact with other Amazon resources.
A service-linked role makes setting up Systems Manager easier because you don’t have to manually add the necessary permissions. Systems Manager defines the permissions of its service-linked roles, and unless defined otherwise, only Systems Manager can assume its roles. The defined permissions include the trust policy and the permissions policy, and that permissions policy can't be attached to any other IAM entity.
You can delete a service-linked role only after first deleting their related resources. This protects your Systems Manager resources because you can't inadvertently remove permission to access the resources.
Note
For non-EC2 nodes in a hybrid and multicloud environment , you need an additional IAM role
that allows those machines to communicate with the Systems Manager service. This is
the IAM service role for Systems Manager. This role grants Amazon Security Token Service (Amazon STS)
AssumeRole trust to the Systems Manager
service. The AssumeRole action returns a set of temporary security
credentials (consisting of an access key ID, a secret access key, and a security
token). You use these temporary credentials to access Amazon resources that you might
not normally have access to. For more information, see Create an IAM service role for a hybrid environment and
AssumeRole in the Amazon Security Token Service API Reference.
For information about other services that support service-linked roles, see Amazon Web Services that work with IAM and look for the services that have Yes in the Service-linked roles column. Choose a Yes with a link to view the service-linked role documentation for that service.