functions/Get-DbaUptime.ps1

function Get-DbaUptime {
    <#
        .SYNOPSIS
            Returns the uptime of the SQL Server instance, and if required the hosting windows server
             
        .DESCRIPTION
            By default, this command returns for each SQL Server instance passed in:
            SQL Instance last startup time, Uptime as a PS TimeSpan, Uptime as a formatted string
            Hosting Windows server last startup time, Uptime as a PS TimeSpan, Uptime as a formatted string
             
        .PARAMETER SqlInstance
            The SQL Server instance that you're connecting to.
 
        .PARAMETER SqlCredential
            Allows you to login to servers using SQL Logins instead of Windows Authentication (AKA Integrated or Trusted). To use:
 
            $scred = Get-Credential, then pass $scred object to the -SqlCredential parameter.
             
            Windows Authentication will be used if SqlCredential is not specified. SQL Server does not accept Windows credentials being passed as credentials.
             
            To connect to SQL Server as a different Windows user, run PowerShell as that user.
 
        .PARAMETER WindowsCredential
            Allows you to authenticate to Windows servers using alternate credentials.
 
            $wincred = Get-Credential, then pass $wincred object to the -WindowsCredential parameter.
             
        .PARAMETER Silent
            If this switch is enabled, the internal messaging functions will be silenced.
 
        .NOTES
            Tags: CIM
            Author: Stuart Moore (@napalmgram), stuart-moore.com
             
            dbatools PowerShell module (https://dbatools.io, clemaire@gmail.com)
            Copyright (C) 2016 Chrissy LeMaire
            License: GNU GPL v3 https://opensource.org/licenses/GPL-3.0
 
        .LINK
            https://dbatools.io/Get-DbaUptime
 
        .EXAMPLE
            Get-DbaUptime -SqlInstance SqlBox1\Instance2
 
            Returns an object with SQL Server start time, uptime as TimeSpan object, uptime as a string, and Windows host boot time, host uptime as TimeSpan objects and host uptime as a string for the sqlexpress instance on winserver
 
        .EXAMPLE
            Get-DbaUptime -SqlInstance winserver\sqlexpress, sql2016
 
            Returns an object with SQL Server start time, uptime as TimeSpan object, uptime as a string, and Windows host boot time, host uptime as TimeSpan objects and host uptime as a string for the sqlexpress instance on host winserver and the default instance on host sql2016
             
        .EXAMPLE
            Get-DbaRegisteredServerName -SqlInstance sql2014 | Get-DbaUptime
 
            Returns an object with SQL Server start time, uptime as TimeSpan object, uptime as a string, and Windows host boot time, host uptime as TimeSpan objects and host uptime as a string for every server listed in the Central Management Server on sql2014
             
    #>

    [CmdletBinding(DefaultParameterSetName = "Default")]
    Param (
        [parameter(Mandatory = $true, ValueFromPipeline = $true)]
        [Alias("ServerInstance", "SqlServer", "ComputerName")]
        [DbaInstanceParameter[]]$SqlInstance,
        [Alias("Credential")]
        [PSCredential]$SqlCredential,
        [PSCredential]$WindowsCredential,
        [switch]$Silent
    )
    
    begin {
        $nowutc = (Get-Date).ToUniversalTime()
    }
    process {
        foreach ($instance in $SqlInstance) {
            $SqlOnly = $false;
            if ($instance.Gettype().FullName -eq [System.Management.Automation.PSCustomObject] ) {
                $servername = $instance.SqlInstance
            }
            elseif ($instance.Gettype().FullName -eq [Microsoft.SqlServer.Management.Smo.Server]) {
                $servername = $instance.NetName
            }
            else {
                $servername = $instance.ComputerName;
            }

            try {
                Write-Message -Level Verbose -Message "Connecting to $instance"
                $server = Connect-SqlInstance -SqlInstance $instance -SqlCredential $sqlcredential
            }
            catch {
                Stop-Function -Message "Failure" -Category ConnectionError -ErrorRecord $_ -Target $instance -Continue
            }
            Write-Message -Level Verbose -Message "Getting start times for $servername"
            #Get tempdb creation date
            $SQLStartTime = $server.Databases["tempdb"].CreateDate
            $SQLUptime = New-TimeSpan -Start $SQLStartTime.ToUniversalTime() -End $nowutc
            $SQLUptimeString = "{0} days {1} hours {2} minutes {3} seconds" -f $($SQLUptime.Days), $($SQLUptime.Hours), $($SQLUptime.Minutes), $($SQLUptime.Seconds)
            
            $WindowsServerName = (Resolve-DbaNetworkName $servername -Credential $WindowsCredential).FullComputerName

            try {
                Write-Message -Level Verbose -Message "Getting WinBootTime via CimInstance for $servername"
                $WinBootTime = (Get-DbaOperatingSystem -ComputerName $windowsServerName -Credential $WindowsCredential -ErrorAction SilentlyContinue).LastBootTime
                $WindowsUptime = New-TimeSpan -start $WinBootTime.ToUniversalTime() -end $nowutc
                $WindowsUptimeString = "{0} days {1} hours {2} minutes {3} seconds" -f $($WindowsUptime.Days), $($WindowsUptime.Hours), $($WindowsUptime.Minutes), $($WindowsUptime.Seconds)
            }
            catch {
                try {
                    Write-Message -Level Verbose -Message "Getting WinBootTime via CimInstance DCOM"
                    $CimOption = New-CimSessionOption -Protocol DCOM
                    $CimSession = New-CimSession -Credential:$WindowsCredential -ComputerName $WindowsServerName -SessionOption $CimOption
                    $WinBootTime = ($CimSession | Get-CimInstance -ClassName Win32_OperatingSystem).LastBootUpTime
                    $WindowsUptime = New-TimeSpan -start $WinBootTime.ToUniversalTime() -end $nowutc
                    $WindowsUptimeString = "{0} days {1} hours {2} minutes {3} seconds" -f $($WindowsUptime.Days), $($WindowsUptime.Hours), $($WindowsUptime.Minutes), $($WindowsUptime.Seconds)
                }
                catch {
                    Stop-Function -Message "Failure getting WinBootTime" -ErrorRecord $_ -Target $instance -Continue
                }
            }
                
            [PSCustomObject]@{
                ComputerName     = $WindowsServerName
                InstanceName     = $server.ServiceName
                SqlServer        = $server.Name
                SqlUptime        = $SQLUptime
                WindowsUptime    = $WindowsUptime
                SqlStartTime     = $SQLStartTime
                WindowsBootTime  = $WinBootTime
                SinceSqlStart    = $SQLUptimeString
                SinceWindowsBoot = $WindowsUptimeString
            }
        }
    }
}