View cluster instances in Amazon EC2 - Amazon EMR
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View cluster instances in Amazon EC2

To help you manage your resources, Amazon EC2 allows you to assign metadata to resources in the form of tags. Each Amazon EC2 tag consists of a key and a value. Tags allow you to categorize your Amazon EC2 resources in different ways: for example, by purpose, owner, or environment.

You can search and filter resources based on the tags. The tags that you assign to resources through your Amazon account are available only to you. Other accounts that share the same resource can't view your tags.

Amazon EMR automatically tags each EC2 instance that it launches with key-value pairs. The keys identify the cluster and the instance group to which the instance belongs. This makes it easy to filter your EC2 instances to show, for example, only those instances that belong to a particular cluster, or to show all of the currently running instances in the instance group for the task. This is especially useful if you run several clusters concurrently or manage large numbers of EC2 instances.

These are the predefined key-value pairs that Amazon EMR assigns:

Key Value Value definition


The ID of the cluster that the instance is provisioned for. It appears in the format j-XXXXXXXXXXXXX and can be up to 256 characters long.



The type of instance group, entered as one of the following values: master, core, or task.

You can view and filter on the tags that Amazon EMR adds. For more information, see Using tags in the Amazon EC2 User Guide for Linux Instances. Because the tags set by Amazon EMR are system tags and cannot be edited or deleted, the sections on displaying and filtering tags are the most relevant.


Amazon EMR adds tags to the EC2 instance when its status updates to Running. If latency occurs between the time that the EC2 instance is provisioned and the time that its status is set to Running, the tags that Amazon EMR sets will appear once the instance starts. If you don't see the tags, wait for a few minutes and refresh the view.