zf-sql/backup.ps1

param(
    [Parameter(Mandatory=$true)]
    [string]$SqlInstance,
    
    [Parameter(Mandatory=$false)]
    [string]$Directory,
    
    [Parameter(Mandatory=$false)]
    [switch]$Force
)

#
# backup.ps1
#
# TODO: Parallelize backups for multiple DBs in the instance
# TODO: Use PowerShell SQL module instead of sqlcmd

$instanceName = $SqlInstance.Split('\')[1]

# Use provided directory parameter or default to instance-based path
if ($Directory) {
    $directory = $Directory
    Write-Host "INFO: Using provided directory: $directory"
} else {
    $directory = "C:\Rubrik\$instanceName"
    Write-Host "INFO: Using default directory: $directory"
}

$fullBackupDay = 'Thursday'
$fullBackupOverdueDays = 7  # Force full backup if last full backup is older than this many days
$checkCluster = $false
#$logFile = "C:\Rubrik\backup-$instanceName.log"
$logFile = "H:\Backup\backup-$instanceName.log"

$fullFlag = $directory + "\last_full.flag"
$diffFlag = $directory + "\last_diff.flag"
$today = (Get-Date).Date

function FlagTakenToday($flagPath) {
    if (Test-Path $flagPath) {
        $flagDate = (Get-Content $flagPath | Out-String).Trim()
        return ($flagDate -eq $today.ToString("yyyy-MM-dd"))
    }
    return $false
}

function GetLastFullBackupDate($flagPath) {
    if (Test-Path $flagPath) {
        $flagDate = (Get-Content $flagPath | Out-String).Trim()
        try {
            return [DateTime]::ParseExact($flagDate, "yyyy-MM-dd", $null)
        }
        catch {
            Write-Log "WARNING: Could not parse last full backup date from flag file: $flagDate"
            return $null
        }
    }
    return $null
}

function IsFullBackupOverdue($flagPath, $overdueDays) {
    $lastFullDate = GetLastFullBackupDate $flagPath
    if ($null -eq $lastFullDate) {
        Write-Log "WARNING: No last full backup date found. Full backup is considered overdue."
        return $true
    }
    
    $daysSinceLastFull = ($today - $lastFullDate).Days
    $isOverdue = $daysSinceLastFull -gt $overdueDays
    
    Write-Log "INFO: Last full backup was $daysSinceLastFull days ago on $($lastFullDate.ToString('yyyy-MM-dd')). Overdue threshold: $overdueDays days."
    
    return $isOverdue
}

function Write-Log($message) {
    $timestamp = Get-Date -Format "yyyy-MM-dd HH:mm:ss"
    $logEntry = "$timestamp $message"
    Add-Content -Path $logFile -Value $logEntry
    Write-Host $logEntry
}

# Check if directory exists and is a symbolic link (unless -Force is specified)
if (-not (Test-Path $directory)) {
    Write-Log "ERROR: Directory '$directory' does not exist. Exiting script."
    exit 1
}

if (-not $Force) {
    $directoryInfo = Get-Item $directory
    if (-not ($directoryInfo.Attributes -band [System.IO.FileAttributes]::ReparsePoint)) {
        Write-Log "ERROR: Directory '$directory' is not a symbolic link. Exiting script."
        exit 1
    }
    Write-Log "INFO: Directory '$directory' exists and is a symbolic link. Target: $($directoryInfo.Target). Proceeding."
} else {
    Write-Log "INFO: Force parameter specified. Skipping symbolic link check for directory '$directory'."
}

if ($checkCluster) {
    # Check if SQL instance is running locally
    $localNode = $env:COMPUTERNAME
    
    $clusterInstance = Get-ClusterResource | Where-Object { $_.ResourceType -eq "SQL Server" -and $_.Name -eq "SQL Server ($instanceName)" }
    if ($clusterInstance) {
        $ownerNode = $clusterInstance.OwnerNode.Name
        if ($ownerNode -ne $localNode) {
            Write-Log "SQL instance '$SqlInstance' is not running on local node '$localNode'. Exiting script."
            exit 1
        } else {
            Write-Log "SQL instance '$SqlInstance' is running on local node '$localNode'. Proceeding."
        }
    } else {
        Write-Log "ERROR: SQL instance '$SqlInstance' not found in cluster resources."
        exit 1
    }
} else {
    Write-Log "INFO: Cluster check is disabled. Proceeding without verification."
}

# Check if full backup is overdue regardless of the day
$isFullBackupOverdue = IsFullBackupOverdue $fullFlag $fullBackupOverdueDays

if ((Get-Date).DayOfWeek -eq $fullBackupDay) {
    if (-not (FlagTakenToday $fullFlag)) {
        $backupType = "FULL"
        $cleanupTime = 168
        Set-Content $fullFlag $today.ToString("yyyy-MM-dd")
        Write-Log "Selected FULL backup (scheduled day). Flag updated."
    } else {
        $backupType = "LOG"
        $cleanupTime = 24
        Write-Log "FULL backup already taken today. Selected LOG backup."
    }
} elseif ($isFullBackupOverdue) {
    if (-not (FlagTakenToday $fullFlag)) {
        $backupType = "FULL"
        $cleanupTime = 168
        Set-Content $fullFlag $today.ToString("yyyy-MM-dd")
        Write-Log "Selected FULL backup (overdue - forcing full backup). Flag updated."
    } else {
        $backupType = "LOG"
        $cleanupTime = 24
        Write-Log "FULL backup already taken today (was overdue). Selected LOG backup."
    }
} else {
    if (-not (FlagTakenToday $diffFlag)) {
        $backupType = "DIFF"
        $cleanupTime = 168
        Set-Content $diffFlag $today.ToString("yyyy-MM-dd")
        Write-Log "Selected DIFF backup. Flag updated."
    } else {
        $backupType = "LOG"
        $cleanupTime = 24
        Write-Log "DIFF backup already taken today. Selected LOG backup."
    }
}

$query = "EXECUTE [dbo].[DatabaseBackup] @Databases = 'ALL_DATABASES', @Directory = '$directory', @BackupType = '$backupType', @Verify = 'N', @CleanupTime = $cleanupTime, @CheckSum = 'Y', @LogToTable = 'Y'"
Write-Log "Executing backup type: $backupType"

$sqlcmdOutput = & sqlcmd -S $SqlInstance -Q $query 2>&1
$sqlcmdExitCode = $LASTEXITCODE

if ($sqlcmdExitCode -eq 0) {
    foreach ($line in $sqlcmdOutput) {
        Write-Log $line
    }
    Write-Log "$backupType Backup execution completed."
} else {
    Write-Log "ERROR: Backup execution failed. Exit code: $sqlcmdExitCode. Output: $sqlcmdOutput"
}