config-iis-log-format.ps1

# ref: https://docs.microsoft.com/en-us/iis/configuration/system.applicationhost/sites/site/logfile/
# ref: https://forums.iis.net/t/1205491.aspx?Add+IIS+8+5+Custom+Logging+Fields+with+Powershell

function Set-WebSiteIISLogFormat {
    param (
        $Site
    )

    $logExtFileFlags = 'Date,Time,ClientIP,UserName,ServerIP,Method,UriStem,UriQuery,HttpStatus,Win32Status,TimeTaken,ServerPort,UserAgent,Referer,Host,HttpSubStatus'
    Set-ItemProperty -Path "IIS:\Sites\$Site" -Name logfile.logExtFileFlags -Value $logExtFileFlags

    $customFields = Get-ItemProperty -Path "IIS:\Sites\$Site" -Name logfile.customFields.collection

    if (-not ($customFields | Where-Object logFieldName -eq X-Forwarded-For)) {
        New-ItemProperty -Path "IIS:\Sites\$Site" -Name logfile.customFields.collection -Value @{
            logFieldName = 'X-Forwarded-For'
            sourceName   = 'X-Forwarded-For'
            sourceType   = 'RequestHeader'
        }
    }
}

function Set-DefaultIISLogFormat {
    $logExtFileFlags = 'Date,Time,ClientIP,UserName,ServerIP,Method,UriStem,UriQuery,HttpStatus,Win32Status,TimeTaken,ServerPort,UserAgent,Referer,Host,HttpSubStatus'
    Set-ItemProperty -Path IIS: -Name siteDefaults.logfile.logExtFileFlags -Value $logExtFileFlags

    $customFields = Get-ItemProperty -Path IIS: -Name siteDefaults.logfile.customFields.collection

    if (-not ($customFields | Where-Object logFieldName -eq X-Forwarded-For)) {
        New-ItemProperty -Path IIS: -Name siteDefaults.logfile.customFields.collection -Value @{
            logFieldName = 'X-Forwarded-For'
            sourceName   = 'X-Forwarded-For'
            sourceType   = 'RequestHeader'
        }
    }
}