Incorrect instance count when using SSM

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What issue did you see ? I used the following to extract all the SSM-managed instances in the account:

ssm_instances = [i['InstanceId'] for i in boto3.client('ssm').describe_instance_information()['InstanceInformationList']]

In the AWS SSM Fleet Manager, the total number of instances is 43 but the output of the command above is only 10. I’m not sure why this is happening.

Steps to reproduce

import boto3
ssm_instances = [i['InstanceId'] for i in boto3.client('ssm').describe_instance_information()['InstanceInformationList']]
print(ssm_instances)

[prandelicious]

Thank you for looking into this! I can confirm that this was indeed due to lack of pagination. I have included pagination support since then and can confirm that I’m getting the correct count of instances in SSM. Appreciate your effort in validating this, @stobrien89!

[stobrien89]

Hi again @prandelicious,

I reviewed this with a teammate and realized it did not occur to me that this could be due to lack of pagination. It could be that the MaxResults default for this operation is 10 (it isn’t listed on the API reference page). Have you tried adding a paginator/iterator to the client?