function Invoke-MinimizeDesignation {
<#
.SYNOPSIS
This wraps the APIGateway/Lambda for scaling environments.  Scales the environment down to a 1x1x1.

.DESCRIPTION
Sends shutdown commands to EC2 instances where the alk:designation tag value = parameter Designation, keeping 1 each of App, Mic and Web running.  1x1x1.

.PARAMETER Fqdn
Fully Qualified Domain Name of the API Gateway.  Each environment/account has a unique API Gateway endpoint.

.PARAMETER Designation
alk:designation tag to filter which instances to query. Case sensitive.

.PARAMETER ApiGatewayKey
Unique key for authenticating to the API Gateway.

.PARAMETER IsTest
Switch to determine if it should actually send the commands to the EC2 instances, or just report back what it will do, without actually sending instance commands.

.PARAMETER ExclusionListCSV
Comma-seperated list of alk:hostname strings to exclude from the shutdown command. Case sensitive.

.EXAMPLE
Invoke-MinimizeDesignation -fqdn "vyq7hqcx55.execute-api.us-east-1.amazonaws.com" -designation "ci1" -apiGatewayKey "123456789" -isTest $true -exclusionList "app2778144"

returns JSON:
[
    {
        "IsExcluded": false,
        "IsApp": false,
        "IsMic": false,
        "IsWeb": true,
        "IsRunning": false,
        "IsStopped": true,
        "InstanceId": "i-0fa21749b4e4b81ea",
        "Designation": "ci1",
        "HostName": "web27425",
        "Environment": "dev",
        "Service": "orb"
    }
]

.NOTES
Dev FQDN : vyq7hqcx55.execute-api.us-east-1.amazonaws.com
Staging FQDN : cox3133b67.execute-api.us-east-1.amazonaws.com
Qa FQDN :
#>
    [CmdletBinding()]

    Param (
        [Parameter(Mandatory = $true)]
        [string] $Fqdn,
        [Parameter(Mandatory = $true)]
        [string] $Designation,
        [Parameter(Mandatory = $true)]
        [string] $ApiGatewayKey,
        [Parameter(Mandatory = $true)]
        [string] $IsTest,
        [Parameter(Mandatory = $false)]
        [AllowEmptyString()]
        [string] $ExclusionListCSV
    )

    [System.Net.ServicePointManager]::SecurityProtocol = "Tls12"

    $ExclusionListCSV = $ExclusionListCSV.Replace(',', '","')


    $jsonBody = '{"Designation":"' + $Designation + '","ExclusionList":["' + $ExclusionListCSV + '"],"IsTest":"' + $IsTest + '"}'
    #Write-Host "Calling Invoke-MinimizeEnvironment with: $jsonBody"
    $response = Invoke-RestMethod -Uri "https://$Fqdn/Prod/MinimizeDesignation" -Headers @{"x-api-key" = $ApiGatewayKey} -Method POST -body $jsonBody -ContentType "application/json"

    return $response
}