AWS Systems Manager
User Guide

Patch a Linux AMI (AWS CLI)

This Systems Manager Automation walkthrough shows you how to use the AWS CLI and the Systems Manager AWS-UpdateLinuxAmi document to automatically patch a Linux AMI with the latest versions of packages that you specify. You can update any of the following Linux versions using this walkthrough: Ubuntu, CentOS, RHEL, SLES, or Amazon Linux AMIs. The AWS-UpdateLinuxAmi document also automates the installation of additional site-specific packages and configurations.

The AWS-UpdateLinuxAmi document enables you to automate image-maintenance tasks without having to author the workflow in JSON or YAML. You can use the AWS-UpdateLinuxAmi document to perform the following types of tasks.

  • Upgrade all distribution packages and Amazon software on an Amazon Linux, Red Hat, Ubuntu, SLES, or Cent OS Amazon Machine Image (AMI). This is the default document behavior.

  • Install SSM Agent on an existing image to enable Systems Manager capabilities, such as remote command execution using Run Command or software inventory collection using Inventory.

  • Install additional software packages.

Before You Begin

Before you begin working with Automation documents, configure roles and, optionally, CloudWatch Events for Automation. For more information, see Setting Up Automation.

The AWS-UpdateLinuxAmi document accepts the following input parameters.

Parameter Type Description

SourceAmiId

String

(Required) The source AMI ID.

InstanceIamRole

String

(Optional) The name of the AWS Identity and Access Management (IAM) instance profile role you created in Setting Up Automation. The instance profile role gives Automation permission to perform actions on your instances, such as executing commands or starting and stopping services. The Automation document uses only the name of the instance profile role. If you specify the Amazon Resource Name (ARN), the Automation execution fails.

AutomationAssumeRole

String

(Optional) The name of the IAM service role you created in Setting Up Automation. The service role (also called an assume role) gives Automation permission to assume your IAM role and perform actions on your behalf. For example, the service role allows Automation to create a new AMI when executing the aws:createImage action in an Automation document. For this parameter, the complete ARN must be specified.

TargetAmiName

String

(Optional) The name of the new AMI after it is created. The default name is a system-generated string that includes the source AMI ID, and the creation time and date.

InstanceType

String

(Optional) The type of instance to launch as the workspace host. Instance types vary by region. The default type is t2.micro.

PreUpdateScript

String

(Optional) URL of a script to run before updates are applied. Default (\"none\") is to not run a script.

PostUpdateScript

String

(Optional) URL of a script to run after package updates are applied. Default (\"none\") is to not run a script.

IncludePackages

String

(Optional) Only update these named packages. By default (\"all\"), all available updates are applied.

ExcludePackages

String

(Optional) Names of packages to hold back from updates, under all conditions. By default (\"none\"), no package is excluded.

Automation Steps

The AWS-UpdateLinuxAmi document includes the following Automation steps, by default.

Step 1: launchInstance (aws:runInstances action)

This step launches an instance using Amazon EC2 userdata and an IAM instance profile role. Userdata installs the appropriate SSM Agent, based on the operating system. Installing SSM Agent enables you to utilize Systems Manager capabilities such as Run Command, State Manager, and Inventory.

Step 2: updateOSSoftware (aws:runCommand action)

This step runs the following commands on the launched instance:

  • Downloads an update script from Amazon S3.

  • Runs an optional pre-update script.

  • Updates distribution packages and Amazon software.

  • Runs an optional post-update script.

The execution log is stored in the /tmp folder for the user to view later.

If you want to upgrade a specific set of packages, you can supply the list using the IncludePackages parameter. When provided, the system attempts to update only these packages and their dependencies. No other updates are performed. By default, when no include packages are specified, the program updates all available packages.

If you want to exclude upgrading a specific set of packages, you can supply the list to the ExcludePackages parameter. If provided, these packages remain at their current version, independent of any other options specified. By default, when no exclude packages are specified, no packages are excluded.

Step 3: stopInstance (aws:changeInstanceState action)

This step stops the updated instance.

Step 4: createImage (aws:createImage action)

This step creates a new AMI with a descriptive name that links it to the source ID and creation time. For example: “AMI Generated by EC2 Automation on {{global:DATE_TIME}} from {{SourceAmiId}}” where DATE_TIME and SourceID represent Automation variables.

Step 5: terminateInstance (aws:changeInstanceState action)

This step cleans up the execution by terminating the running instance.

Output

The execution returns the new AMI ID as output.

Note

By default, when Automation runs the AWS-UpdateLinuxAmi document, the system creates a temporary instance in the default VPC (172.30.0.0/16). If you deleted the default VPC, you will receive the following error:

VPC not defined 400

To solve this problem, you must make a copy of the AWS-UpdateLinuxAmi document and specify a subnet ID. For more information, see VPC not defined 400.

To create a patched AMI using Automation

  1. Download the AWS CLI to your local machine.

  2. Run the following command to run the AWS-UpdateLinuxAmi document and run the Automation workflow. In the parameters section, In the parameters section, specify your Automation role, an AMI source ID, and an Amazon EC2 instance profile role.

    aws ssm start-automation-execution \ --document-name "AWS-UpdateLinuxAmi" \ --parameters \ SourceAmiId=ami-e6d5d2f1

    The command returns an execution ID. Copy this ID to the clipboard. You will use this ID to view the status of the workflow.

    { "AutomationExecutionId": "ID" }
  3. To view the workflow execution using the CLI, run the following command:

    aws ssm describe-automation-executions
  4. To view details about the execution progress, run the following command.

    aws ssm get-automation-execution --automation-execution-id ID

    The update process can take 30 minutes or more to complete.

    Note

    You can also monitor the status of the workflow in the console. In the execution list, choose the execution you just ran and then choose the Steps tab. This tab shows you the status of the workflow actions.

After the workflow finishes, launch a test instance from the updated AMI to verify changes.

Note

If any step in the workflow fails, information about the failure is listed on the Automation Executions page. The workflow is designed to terminate the temporary instance after successfully completing all tasks. If a step fails, the system might not terminate the instance. So if a step fails, manually terminate the temporary instance.