function Get-CachedInstances {
<#
.SYNOPSIS
    Get the cached instance data. Defaults to dev data

.PARAMETER ProfileName
    A valid ProfileName
#>
    [CmdletBinding()]
    [OutputType([object[]])]
    param (
        [Parameter(Mandatory = $false)]
        [string]$ProfileName = (Get-LocalCachedAWSProfile),
        [Parameter(Mandatory = $false)]
        [ValidateScript({
            $ProfileName = Get-Coalesce $PSCmdlet.MyInvocation.BoundParameters["ProfileName"], (Get-LocalCachedAWSProfile)
            (Get-Designations -ProfileName $ProfileName) -contains $_
        })]
        [string]$Designation,
        [Parameter()]
        [switch]$MIC,
        [Parameter()]
        [switch]$WEB,
        [Parameter()]
        [switch]$APP,
        [Parameter()]
        [switch]$TeamCity,
        [Parameter()]
        [switch]$IncludeDR,
        [Parameter()]
        [switch]$OnlyDR
    )

    $logLead = (Get-LogLeadName)

    # if no server types were selected, then we want all server types
    $noServerTypesSelected = $false
    if (-not $WEB -and -not $MIC -and -not $APP -and -not $TeamCity) {
        $noServerTypesSelected = $true
    }
    # true up selection as required
    $WEB = $WEB -or $noServerTypesSelected
    $MIC = $MIC -or $noServerTypesSelected
    $APP = $APP -or $noServerTypesSelected
    $TeamCity = $TeamCity -or $noServerTypesSelected

    if ($OnlyDR -and $IncludeDR) {
        Write-Warning "$logLead : You can not select OnlyDR and IncludeDR. Opting for IncludeDR."
        $OnlyDR = $false
    }

    $designationSpecified = -not [string]::IsNullOrWhiteSpace($Designation)

    Assert-ValidAWSProfileName -ProfileName $ProfileName

    $cachePath = Get-CachePathEC2Instance -ProfileName $ProfileName

    if (!(Test-Path -Path $cachePath)) {
        Write-Warning "$logLead : No file found at [$cachePath]. You probably should call Checkpoint-EC2Instances -ProfileName $ProfileName"
        return @()
    }

    if (Test-WasFileModifiedWithin -Path $cachePath -Last Week) {
        if (Test-IsCurrentAWSUserSessionValid -ProfileName $ProfileName) {
            Write-Information "$logLead : Instance information is more than 7 days out of date, and you have a valid session token. Updating EC2 instance information."
            Checkpoint-EC2Instances -ProfileName $ProfileName
        } else {
            Write-Warning "$logLead : Your $ProfileName designations file is more than 7 days out of date. Do you need to run [Checkpoint-EC2Instances -ProfileName $ProfileName] again?"
        }
    }

    $instances = Get-Json -Path $cachePath | Where-Object {
        $instance = $_
        $result = $false
        if ($WEB) { $result = $result -or "$($instance.Hostname)".ToLower().StartsWith('web') }
        if ($MIC) { $result = $result -or "$($instance.Hostname)".ToLower().StartsWith('mic') }
        if ($APP) { $result = $result -or "$($instance.Hostname)".ToLower().StartsWith('app') }
        if ($TeamCity) { $result = $result -or "$($instance.Hostname)".ToLower().StartsWith('tea') }
        if ($noServerTypesSelected) { $result = $true }
        $result
    } | Where-Object {
        $instance = $_
        if ($OnlyDR) {
            $instance.tags."alk:env" -eq "dr"
        } else {
            if ($IncludeDR) {
                $true
            } else {
                $instance.tags."alk:env" -ne "dr"
            }
        }
    } | Where-Object {
        $instance = $_
        if ($designationSpecified) { $instance.Designation -eq $Designation }
        else { $true }
    }

    return ($instances | ConvertTo-Instance)
}