AWS System Manager Agent is installed by default on Ubuntu 16.04 LTS and 18.04 LTS AMIs

The AWS System Manager Agent is preinstalled on Ubuntu 16.04 LTS or the later versions and Amazon Machine Image 18.04 LTS. When the AWS System Manager agent is pre-installed the users can then use AWS System manager features such as State Manager, Run Command, Patch and Inventory Manager. The agent is installed by default will help you to save time by eradicating the need for manually logging into each instance and install the agent. The AWS System Manager Agent is an open source and it is available on GitHub so you can customize the System Manager as required. You will need to apply AWS Identity and Access Management policies to the instance to use the AWS System Manager and there will be no additional configuration involved