Cross-region reading of SSM parameter values.

SSMParameterReader.fs

open Constructs
open Amazon.CDK.CustomResources

type SSMParameterReaderProps
  (
    ParameterName : string,
    Region: string
  ) =

  member _.ParameterName = ParameterName
  member _.Region = Region

/// Cross-region reading of SSM parameter values.
// Based on
//  - https://stackoverflow.com/a/59774628/1259408
//  - https://docs.aws.amazon.com/cdk/api/latest/docs/custom-resources-readme.html#get-the-latest-version-of-a-secure-ssm-parameter
type SSMParameterReader(scope : Construct, id : string, props : SSMParameterReaderProps) =
  inherit AwsCustomResource(scope, id,
    AwsCustomResourceProps(
      Policy =
        AwsCustomResourcePolicy.FromSdkCalls(
          SdkCallsPolicyOptions(
            Resources = AwsCustomResourcePolicy.ANY_RESOURCE
          )
        ),
      OnUpdate =
        AwsSdkCall(
          Service = "SSM",
          Action = "getParameter",
          Parameters = dict [
            "Name", props.ParameterName
          ],
          Region = props.Region,
          // Update physical id to always fetch the latest version
          PhysicalResourceId = PhysicalResourceId.Of(System.DateTime.Now.ToString("o"))
        )
    )
  )

  member this.GetParameterValue() = this.GetResponseField("Parameter.Value")