Issue

In the Datadog Agent v6 and v7, the default Agent in-app hostname for UNIX platforms on EC2 is the instance-id. For Windows hosts, the default Agent in-app hostname is the operating system hostname that starts with EC2AMAZ-.

For v6.18.0+ and v7.18.0+, the Agent logs the following warning for Windows hosts on EC2 where the hostname starts with EC2AMAZ-:

You may want to use the EC2 instance-id for the in-app hostname. For more information: https://docs.datadoghq.com/ec2-use-win-prefix-detection

Resolution

If you see the warning message above, your options are:

• Continue using the in-app hostname (do nothing)
• Use the instance-id by following the instructions below

EC2 instance-id for Windows host on EC2

For v6.15.0+ and v7.15.0+, the Agent supports the configuration option ec2_use_windows_prefix_detection (default: false). When set to true, the in-app hostname for a Windows EC2 host is the instance-id for:

• New hosts (enabling this option works immediately)
• Hosts already reporting to Datadog. After enabling, message Datadog support to change the in-app hostname to the EC2 instance-id.