Reference: ec2messages, ssmmessages, and Other API Calls
If you monitor API calls, you might see calls to the following APIs.
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ec2messages:AcknowledgeMessage
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ec2messages:DeleteMessage
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ec2messages:FailMessage
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ec2messages:GetEndpoint
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ec2messages:GetMessages
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ec2messages:SendReply
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ssmmessages:CreateControlChannel
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ssmmessages:CreateDataChannel
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ssmmessages:OpenControlChannel
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ssmmessages:OpenDataChannel
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UpdateInstanceInformation
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ListInstanceAssociations
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DescribeInstanceProperties
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DescribeDocumentParameters
These special calls are used by Systems Manager for various operations.
ec2messages API calls
Calls to ec2messages:* APIs are calls to the ec2messages
endpoint. Systems Manager uses this endpoint to make calls from SSM Agent to the Systems
Manager service in
the cloud. This endpoint is required to send and receive commands.
ssmmessages API calls
Systems Manager uses the ssmmessages endpoint to to make calls from SSM Agent to the
Session Manager service in the cloud. This endpoint is required to create and delete
session
channels with the Session Manager service in the cloud.
Instance-related API calls
UpdateInstanceInformation: SSM Agent calls the Systems Manager service
in the cloud every five minutes to provide heartbeat information. This call is necessary
to maintain a heartbeat with the agent so that the service knows the agent is
functioning as expected.
ListInstanceAssociations: The agent calls this API to see if a
new Systems Manager State Manager association is available. This API is required for
State Manager to
function.
DescribeInstanceProperties and DescribeDocumentParameters: Systems Manager calls these APIs to render specific nodes in
the Amazon EC2 console. The DescribeInstanceProperties API displays
the Managed Instances node in the left navigation. The DescribeDocumentParameters API displays the
Documents node in the left navigation.
