Update a golden AMI using Automation, AWS Lambda, and Parameter Store - AWS Systems Manager

Update a golden AMI using Automation, AWS Lambda, and Parameter Store

The following example uses the model where an organization maintains and periodically patches their own, proprietary AMIs rather than building from Amazon Elastic Compute Cloud (Amazon EC2) AMIs.

The following procedure shows how to automatically apply operating system (OS) patches to an AMI that is already considered to be the most up-to-date or latest AMI. In the example, the default value of the parameter SourceAmiId is defined by a AWS Systems Manager Parameter Store parameter called latestAmi. The value of latestAmi is updated by an AWS Lambda function invoked at the end of the automation. As a result of this Automation process, the time and effort spent patching AMIs is minimized because patching is always applied to the most up-to-date AMI. Parameter Store and Automation are capabilities of AWS Systems Manager.

Before you begin

Configure Automation roles and, optionally, Amazon EventBridge for Automation. For more information, see Setting up Automation.

Task 1: Create a parameter in Systems Manager Parameter Store

Create a string parameter in Parameter Store that uses the following information:

  • Name: latestAmi.

  • Value: An AMI ID. For example: ami-188d6e0e.

For information about how to create a Parameter Store string parameter, see Creating Systems Manager parameters.

Task 2: Create an IAM role for AWS Lambda

Use the following procedure to create an IAM service role for AWS Lambda. These policies give Lambda permission to update the value of the latestAmi parameter using a Lambda function and Systems Manager.

To create an IAM service role for Lambda
  1. Sign in to the AWS Management Console and open the IAM console at https://console.aws.amazon.com/iam/.

  2. In the navigation pane, choose Policies, and then choose Create policy.

  3. Choose the JSON tab.

  4. Replace the default contents with the following policy. Replace each example resource placeholder with your own information.

    { "Version": "2012-10-17", "Statement": [ { "Effect": "Allow", "Action": "logs:CreateLogGroup", "Resource": "arn:aws:logs:region:123456789012:*" }, { "Effect": "Allow", "Action": [ "logs:CreateLogStream", "logs:PutLogEvents" ], "Resource": [ "arn:aws:logs:region:123456789012:log-group:/aws/lambda/function name:*" ] } ] }
  5. Choose Next: Tags.

  6. (Optional) Add one or more tag-key value pairs to organize, track, or control access for this policy.

  7. Choose Next: Review.

  8. On the Review policy page, for Name, enter a name for the inline policy, such as amiLambda.

  9. Choose Create policy.

  10. Repeat steps 2 and 3.

  11. Paste the following policy. Replace each example resource placeholder with your own information.

    { "Version": "2012-10-17", "Statement": [ { "Effect": "Allow", "Action": "ssm:PutParameter", "Resource": "arn:aws:ssm:region:123456789012:parameter/latestAmi" }, { "Effect": "Allow", "Action": "ssm:DescribeParameters", "Resource": "*" } ] }
  12. Choose Next: Tags.

  13. (Optional) Add one or more tag-key value pairs to organize, track, or control access for this policy.

  14. Choose Next: Review.

  15. On the Review policy page, for Name, enter a name for the inline policy, such as amiParameter.

  16. Choose Create policy.

  17. In the navigation pane, choose Roles, and then choose Create role.

  18. Immediately under Use case, choose Lambda, and then choose Next.

  19. On the Add permissions page, use the Search field to locate the two policies you created earlier.

  20. Select the check box next to the policies, and then choose Next.

  21. For Role name, enter a name for your new role, such as lambda-ssm-role or another name that you prefer.

    Note

    Because various entities might reference the role, you cannot change the name of the role after it has been created.

  22. (Optional) Add one or more tag key-value pairs to organize, track, or control access for this role, and then choose Create role.

Task 3: Create an AWS Lambda function

Use the following procedure to create a Lambda function that automatically updates the value of the latestAmi parameter.

To create a Lambda function
  1. Sign in to the AWS Management Console and open the AWS Lambda console at https://console.aws.amazon.com/lambda/.

  2. Choose Create function.

  3. On the Create function page, choose Author from scratch.

  4. For Function name, enter Automation-UpdateSsmParam.

  5. For Runtime, choose Python 3.8.

  6. For Architecture, select the type of computer processor for Lambda to use to run the function, x86_64 or arm64,

  7. In the Permissions section, expand Change default execution role.

  8. Choose Use an existing role, and then choose the service role for Lambda that you created in Task 2.

  9. Choose Create function.

  10. In the Code source area, on the lambda_function tab, delete the pre-populated code in the field, and then paste the following code sample.

    from __future__ import print_function import json import boto3 print('Loading function') #Updates an SSM parameter #Expects parameterName, parameterValue def lambda_handler(event, context): print("Received event: " + json.dumps(event, indent=2)) # get SSM client client = boto3.client('ssm') #confirm parameter exists before updating it response = client.describe_parameters( Filters=[ { 'Key': 'Name', 'Values': [ event['parameterName'] ] }, ] ) if not response['Parameters']: print('No such parameter') return 'SSM parameter not found.' #if parameter has a Description field, update it PLUS the Value if 'Description' in response['Parameters'][0]: description = response['Parameters'][0]['Description'] response = client.put_parameter( Name=event['parameterName'], Value=event['parameterValue'], Description=description, Type='String', Overwrite=True ) #otherwise just update Value else: response = client.put_parameter( Name=event['parameterName'], Value=event['parameterValue'], Type='String', Overwrite=True ) responseString = 'Updated parameter %s with value %s.' % (event['parameterName'], event['parameterValue']) return responseString
  11. Choose File, Save.

  12. To test the Lambda function, from the Test menu, choose Configure test event.

  13. For Event name, enter a name for the test event, such as MyTestEvent.

  14. Replace the existing text with the following JSON. Replace AMI ID with your own information to set your latestAmi parameter value.

    { "parameterName":"latestAmi", "parameterValue":"AMI ID" }
  15. Choose Save.

  16. Choose Test to test the function. On the Execution result tab, the status should be reported as Succeeded, along with other details about the update.

Task 4: Create a runbook and patch the AMI

Use the following procedure to create and run a runbook that patches the AMI you specified for the latestAmi parameter. After the automation completes, the value of latestAmi is updated with the ID of the newly-patched AMI. Subsequent automations use the AMI created by the previous execution.

To create and run the runbook
  1. Open the AWS Systems Manager console at https://console.aws.amazon.com/systems-manager/.

  2. In the navigation pane, choose Documents.

  3. For Create document, choose Automation.

  4. For Name, enter UpdateMyLatestWindowsAmi.

  5. Choose the Editor tab, and then choose Edit.

  6. Choose OK when prompted.

  7. In the Document editor field, replace the default content with the following YAML sample runbook content.

    --- description: Systems Manager Automation Demo - Patch AMI and Update ASG schemaVersion: '0.3' assumeRole: '{{ AutomationAssumeRole }}' parameters: AutomationAssumeRole: type: String description: '(Required) The ARN of the role that allows Automation to perform the actions on your behalf. If no role is specified, Systems Manager Automation uses your IAM permissions to execute this document.' default: '' SourceAMI: type: String description: The ID of the AMI you want to patch. default: '{{ ssm:latestAmi }}' SubnetId: type: String description: The ID of the subnet where the instance from the SourceAMI parameter is launched. SecurityGroupIds: type: StringList description: The IDs of the security groups to associate with the instance that's launched from the SourceAMI parameter. NewAMI: type: String description: The name of of newly patched AMI. default: 'patchedAMI-{{global:DATE_TIME}}' InstanceProfile: type: String description: The name of the IAM instance profile you want the source instance to use. SnapshotId: type: String description: (Optional) The snapshot ID to use to retrieve a patch baseline snapshot. default: '' RebootOption: type: String description: '(Optional) Reboot behavior after a patch Install operation. If you choose NoReboot and patches are installed, the instance is marked as non-compliant until a subsequent reboot and scan.' allowedValues: - NoReboot - RebootIfNeeded default: RebootIfNeeded Operation: type: String description: (Optional) The update or configuration to perform on the instance. The system checks if patches specified in the patch baseline are installed on the instance. The install operation installs patches missing from the baseline. allowedValues: - Install - Scan default: Install mainSteps: - name: startInstances action: 'aws:runInstances' timeoutSeconds: 1200 maxAttempts: 1 onFailure: Abort inputs: ImageId: '{{ SourceAMI }}' InstanceType: m5.large MinInstanceCount: 1 MaxInstanceCount: 1 IamInstanceProfileName: '{{ InstanceProfile }}' SubnetId: '{{ SubnetId }}' SecurityGroupIds: '{{ SecurityGroupIds }}' - name: verifyInstanceManaged action: 'aws:waitForAwsResourceProperty' timeoutSeconds: 600 inputs: Service: ssm Api: DescribeInstanceInformation InstanceInformationFilterList: - key: InstanceIds valueSet: - '{{ startInstances.InstanceIds }}' PropertySelector: '$.InstanceInformationList[0].PingStatus' DesiredValues: - Online onFailure: 'step:terminateInstance' - name: installPatches action: 'aws:runCommand' timeoutSeconds: 7200 onFailure: Abort inputs: DocumentName: AWS-RunPatchBaseline Parameters: SnapshotId: '{{SnapshotId}}' RebootOption: '{{RebootOption}}' Operation: '{{Operation}}' InstanceIds: - '{{ startInstances.InstanceIds }}' - name: stopInstance action: 'aws:changeInstanceState' maxAttempts: 1 onFailure: Continue inputs: InstanceIds: - '{{ startInstances.InstanceIds }}' DesiredState: stopped - name: createImage action: 'aws:createImage' maxAttempts: 1 onFailure: Continue inputs: InstanceId: '{{ startInstances.InstanceIds }}' ImageName: '{{ NewAMI }}' NoReboot: false ImageDescription: Patched AMI created by Automation - name: terminateInstance action: 'aws:changeInstanceState' maxAttempts: 1 onFailure: Continue inputs: InstanceIds: - '{{ startInstances.InstanceIds }}' DesiredState: terminated - name: updateSsmParam action: aws:invokeLambdaFunction timeoutSeconds: 1200 maxAttempts: 1 onFailure: Abort inputs: FunctionName: Automation-UpdateSsmParam Payload: '{"parameterName":"latestAmi", "parameterValue":"{{createImage.ImageId}}"}' outputs: - createImage.ImageId
  8. Choose Create automation.

  9. In the navigation pane, choose Automation, and then choose Execute automation.

  10. In the Choose document page, choose the Owned by me tab.

  11. Search for the UpdateMyLatestWindowsAmi runbook, and select the button in the UpdateMyLatestWindowsAmi card.

  12. Choose Next.

  13. Choose Simple execution.

  14. Specify values for the input parameters.

  15. Choose Execute.

  16. After the automation completes, choose Parameter Store in the navigation pane and confirm that the new value for latestAmi matches the value returned by the automation. You can also verify the new AMI ID matches the Automation output in the AMIs section of the Amazon EC2 console.