I am looking at SSM instance ping status (PingStatus) information, as returned by the describe_instance_information boto3 calls or as displayed in the SSM console for Managed Instances. But it is not clear to me what the values represent in all cases. From documentation such as this I understand there are 3 status values:
"Online" seems pretty self explanatory, and I can make a relatively safe guess at what "ConnectionLost" means, but then what does "Inactive" mean? What exactly do each of these ping status values indicate? I want to understand what is different about "ConnectionLost" and "Inactive" so I can respond more appropriately to the status when I see it.
You can read at the bottom of the same documentation.
If the status is
Online
Then your instance is ready to be managed using Run Command.
Inactive
The instance has one or more of the following problems.
SSM Agent is not installed.
The instance does not have outbound internet connectivity.
The instance was not launched with an IAM role that enables it to communicate with the SSM API, or the permissions for the IAM role are not correct for Run Command. For more information, see Create an IAM Instance Profile for Systems Manager.
The above document does not contain more information about connection lost, but here is something relevant.
connection lost
If an instance fails a health check, AWS OpsWorks Stacks autoheals registered Amazon EC2 instances and changes the status of registered on-premises instances to connection lost.