Programming Amazon Web Services

Controlling Instances

The EC2 service provides API operations for managing the lifecycle of your instances. We will start by looking at how you can terminate your running instances; it is wise to know how to do this before you start launching instances that will incur fees for every hour they run.

Stop Running Instances

The TerminateInstances operation shown in Table 5-10 terminates one or more instances running in your EC2 account. An instance can be terminated multiple times without any ill effects.

Table 5-10. TerminateInstances request parameters

Parameter Name	Value	Required?
Action	TerminateInstances	Yes
InstanceId (Indexed)	The identifiers of one or more instances to terminate	Yes

Here is an XML document returned by the operation:

<TerminateInstancesResponse 
                          xmlns='http://ec2.amazonaws.com/doc/2007-08-29/'>
  <instancesSet>
    <item>
      <instanceId>i-ec43a885</instanceId>
      <shutdownState>
        <code>32</code>
        <name>shutting-down</name>
      </shutdownState>
      <previousState>
        <code>16</code>
        <name>running</name>
      </previousState>
    </item>
  </instancesSet>
</TerminateInstancesResponse>

The response document returned by the operation includes a listing of the instances that were acted upon by the operation with information about the instance’s prior status and its status as a result of the TerminateInstances operation. Each item element in the XML document describes the status of one instance, Table 5-11 lists the contents of this element.

Table 5-11. TerminateInstancesResponseInfoType element

Element Name	Description ...