# ResolveSsmParameterAtLaunchImage

Select the image based on a given SSM parameter at instance launch time.

This Machine Image comes with an imageId as `resolve:ssm:parameter-name` or `resolve:ssm:parameter-name:version` format
as described in the document:

Extends: ResolveSsmParameterAtLaunchImage
Implements: IMachineImage

- Source: [`aws-ec2/lib/machine-image/machine-image.ts`](https://github.com/aws/aws-cdk/blob/v2.273.0/packages/aws-cdk-lib/aws-ec2/lib/machine-image/machine-image.ts#L247)
- Type last changed: v2.209.0 · 5 Aug 2025

## Example

```ts
// The code below shows an example of how to instantiate this type.
// The values are placeholders you should change.
import { aws_ec2 as ec2 } from 'aws-cdk-lib';

declare const userData: ec2.UserData;
const resolveSsmParameterAtLaunchImage = new ec2.ResolveSsmParameterAtLaunchImage('parameterName', /* all optional props */ {
  additionalCacheKey: 'additionalCacheKey',
  cachedInContext: false,
  os: ec2.OperatingSystemType.LINUX,
  parameterVersion: 'parameterVersion',
  userData: userData,
});
```

## Initializer

```ts
new ResolveSsmParameterAtLaunchImage(parameterName: string, props?: SsmParameterImageOptions)
```

## Properties

- `parameterName`: string (required) — Name of the SSM parameter we're looking up.

## Methods

- `getImage(_scope: Construct): MachineImageConfig` — Return the image to use in the given context.