function Checkpoint-EC2Instances {
<#
.SYNOPSIS
    Get the EC2 instances for the specified profile and save them in the cached files

.PARAMETER ProfileName
    A valid ProfileName
#>
    [CmdletBinding()]
    [OutputType([object[]])]
    param(
        [Parameter(Mandatory = $true)]
        [string]$ProfileName
    )

    $activityLabel = "Gathering instances"

    Assert-ValidAWSProfileName -ProfileName $ProfileName

    if (!(Test-IsCurrentAWSUserSessionValid -ProfileName $ProfileName)) {
        throw "User session is invalid. Please run Update-AWSProfile $($ProfileName.Replace('temp-',''))"
    }

    $PercentComplete = 1
    Write-ProgressHelper -Activity $activityLabel -Status "Starting" -PercentComplete $PercentComplete
    $PercentComplete += 1

    $allInstances = @()
    foreach ($region in (Get-AWSRegions)) {
        Write-ProgressHelper -Activity $activityLabel -Status $Region -PercentComplete $PercentComplete
        $instances = Get-EC2Instance -Region $region -ProfileName $ProfileName
        $PercentComplete += 20
        Write-ProgressHelper -Activity $activityLabel -Status $Region -PercentComplete $PercentComplete

        $allInstances += ConvertFrom-EC2Instance -Instances $instances.Instances

        $PercentComplete += 4
        Write-ProgressHelper -Activity $activityLabel -Status $Region -PercentComplete $PercentComplete
    }

    $ProfileName = $ProfileName.Replace("temp-","").ToLower()

    Write-ProgressHelper -Activity $activityLabel -Status "Saving instance file" -PercentComplete 98
    $cacheFile = Get-CachePathEC2Instance -ProfileName $ProfileName
    ConvertTo-Json $allInstances -Depth 10 | Set-Content -Path $cacheFile

    Write-ProgressHelper -Activity $activityLabel -Status "Saving designation file" -PercentComplete 99
    $cacheFile = Get-CachePathDesignations -ProfileName $ProfileName
    $allInstances.Designation | Sort-Object | Get-Unique | Set-Content -Path $cacheFile

    Write-Progress -Activity $activityLabel -Completed
}