Logging in powershell with log rotation

logger.ps1

# all logging settins are here on top
$logFile = "log-$(gc env:computername).log"
$logLevel = "DEBUG" # ("DEBUG","INFO","WARN","ERROR","FATAL")
$logSize = 1mb # 30kb
$logCount = 10
# end of settings

function Write-Log-Line ($line) {
    Add-Content $logFile -Value $Line
    Write-Host $Line
}

# http://stackoverflow.com/a/38738942
Function Write-Log {
    [CmdletBinding()]
    Param(
    [Parameter(Mandatory=$True)]
    [string]
    $Message,
    
    [Parameter(Mandatory=$False)]
    [String]
    $Level = "DEBUG"
    )

    $levels = ("DEBUG","INFO","WARN","ERROR","FATAL")
    $logLevelPos = [array]::IndexOf($levels, $logLevel)
    $levelPos = [array]::IndexOf($levels, $Level)
    $Stamp = (Get-Date).toString("yyyy/MM/dd HH:mm:ss:fff")

    if ($logLevelPos -lt 0){
        Write-Log-Line "$Stamp ERROR Wrong logLevel configuration [$logLevel]"
    }
    
    if ($levelPos -lt 0){
        Write-Log-Line "$Stamp ERROR Wrong log level parameter [$Level]"
    }

    # if level parameter is wrong or configuration is wrong I still want to see the 
    # message in log
    if ($levelPos -lt $logLevelPos -and $levelPos -ge 0 -and $logLevelPos -ge 0){
        return
    }

    $Line = "$Stamp $Level $Message"
    Write-Log-Line $Line
}

# https://gallery.technet.microsoft.com/scriptcenter/PowerShell-Script-to-Roll-a96ec7d4
function Reset-Log 
{ 
    # function checks to see if file in question is larger than the paramater specified 
    # if it is it will roll a log and delete the oldes log if there are more than x logs. 
    param([string]$fileName, [int64]$filesize = 1mb , [int] $logcount = 5) 
     
    $logRollStatus = $true 
    if(test-path $filename) 
    { 
        $file = Get-ChildItem $filename 
        if((($file).length) -ige $filesize) #this starts the log roll 
        { 
            $fileDir = $file.Directory 
            #this gets the name of the file we started with 
            $fn = $file.name
            $files = Get-ChildItem $filedir | ?{$_.name -like "$fn*"} | Sort-Object lastwritetime 
            #this gets the fullname of the file we started with 
            $filefullname = $file.fullname
            #$logcount +=1 #add one to the count as the base file is one more than the count 
            for ($i = ($files.count); $i -gt 0; $i--) 
            {  
                #[int]$fileNumber = ($f).name.Trim($file.name) #gets the current number of 
                # the file we are on 
                $files = Get-ChildItem $filedir | ?{$_.name -like "$fn*"} | Sort-Object lastwritetime 
                $operatingFile = $files | ?{($_.name).trim($fn) -eq $i} 
                if ($operatingfile) 
                 {$operatingFilenumber = ($files | ?{($_.name).trim($fn) -eq $i}).name.trim($fn)} 
                else 
                {$operatingFilenumber = $null} 
 
                if(($operatingFilenumber -eq $null) -and ($i -ne 1) -and ($i -lt $logcount)) 
                { 
                    $operatingFilenumber = $i 
                    $newfilename = "$filefullname.$operatingFilenumber" 
                    $operatingFile = $files | ?{($_.name).trim($fn) -eq ($i-1)} 
                    write-host "moving to $newfilename" 
                    move-item ($operatingFile.FullName) -Destination $newfilename -Force 
                } 
                elseif($i -ge $logcount) 
                { 
                    if($operatingFilenumber -eq $null) 
                    {  
                        $operatingFilenumber = $i - 1 
                        $operatingFile = $files | ?{($_.name).trim($fn) -eq $operatingFilenumber} 
                        
                    } 
                    write-host "deleting " ($operatingFile.FullName) 
                    remove-item ($operatingFile.FullName) -Force 
                } 
                elseif($i -eq 1) 
                { 
                    $operatingFilenumber = 1 
                    $newfilename = "$filefullname.$operatingFilenumber" 
                    write-host "moving to $newfilename" 
                    move-item $filefullname -Destination $newfilename -Force 
                } 
                else 
                { 
                    $operatingFilenumber = $i +1  
                    $newfilename = "$filefullname.$operatingFilenumber" 
                    $operatingFile = $files | ?{($_.name).trim($fn) -eq ($i-1)} 
                    write-host "moving to $newfilename" 
                    move-item ($operatingFile.FullName) -Destination $newfilename -Force    
                } 
            } 
          } 
         else 
         { $logRollStatus = $false} 
    } 
    else 
    { 
        $logrollStatus = $false 
    } 
    $LogRollStatus 
} 

# to null to avoid output
$Null = @(
    Reset-Log -fileName $logFile -filesize $logSize -logcount $logCount
)

test.ps1

. .\logger.ps1

Write-Log "Started" "INFO"

for ($i = 100; $i -gt 0; $i--) 
{ 
    Write-Log "debug message"
    Write-Log "debug message2" "DEBUG"
    Write-Log "info message" "INFO"
    Write-Log "warn message" "WARN"
    Write-Log "error message" "ERROR"
    Write-Log "fatal message" "FATAL"
    Write-Log "message with wrong level" "WRONG"
}

@arberg
It seems like the roll only works when there are more than 1 file to start. Otherwise I get error "The property 'count' cannot be found on this object." Am I missing something? Sorry I don't have a fix for it at this point (except that I copy/renamed my log so it would have 2) but I'll be working on it as I get time.

@mntlfngs

Its probably because a list was one, and powershell interprets that by removing list unless using @(). I couldn't reproduce the problem, but I have added those, to be safe. I also fixed it so it works without extensions on log-file.

@arberg
Thanks. I got time to tinker and did some changes that made it work for me. Created a fork with my mods .

Just updated my fork with something that I think is working pretty slick now. Quite happy with it.