【PowerShell】プロセスを監視して自動再起動する方法｜ログ・多重起動防止

$ProcessName = "SampleApp"
$ExePath = "C:\Apps\SampleApp\SampleApp.exe"
$IntervalSeconds = 60

while ($true) {
    $process = Get-Process -Name $ProcessName -ErrorAction SilentlyContinue

    if (-not $process) {
        Start-Process -FilePath $ExePath
    }

    Start-Sleep -Seconds $IntervalSeconds
}

$ExePath = "C:\Apps\SampleApp\SampleApp.exe"
$ProcessFile = Split-Path -Path $ExePath -Leaf

Get-CimInstance Win32_Process -Filter "Name = '$ProcessFile'" |
    Where-Object { $_.ExecutablePath -eq $ExePath } |
    Select-Object ProcessId, Name, ExecutablePath, CommandLine

param(
    [string]$ExePath = "C:\Apps\SampleApp\SampleApp.exe",
    [string]$WorkingDirectory = "C:\Apps\SampleApp",
    [string[]]$ArgumentList = @(),
    [int]$IntervalSeconds = 60,
    [int]$RestartCooldownSeconds = 300,
    [int]$MaxRestarts = 3,
    [int]$RestartWindowMinutes = 60,
    [int]$StartupGraceSeconds = 10,
    [string]$LogPath = "C:\Logs\process-monitor.log"
)

$ErrorActionPreference = "Stop"

if (-not (Test-Path -LiteralPath $ExePath)) {
    throw "Executable file was not found: $ExePath"
}

if (-not (Test-Path -LiteralPath $WorkingDirectory)) {
    throw "Working directory was not found: $WorkingDirectory"
}

$logDirectory = Split-Path -Path $LogPath -Parent
if ($logDirectory -and -not (Test-Path -LiteralPath $logDirectory)) {
    New-Item -Path $logDirectory -ItemType Directory -Force | Out-Null
}

$processFile = Split-Path -Path $ExePath -Leaf
$mutexName = "Global\ProcessMonitor_$($processFile -replace '[^a-zA-Z0-9_]', '_')"
$createdNew = $false
$mutex = [System.Threading.Mutex]::new($true, $mutexName, [ref]$createdNew)

if (-not $createdNew) {
    "Another monitor is already running. Mutex: $mutexName" |
        Out-File -FilePath $LogPath -Append -Encoding UTF8
    exit 2
}

function Write-MonitorLog {
    param([string]$Message)

    $line = "{0} {1}" -f (Get-Date -Format "yyyy-MM-dd HH:mm:ss"), $Message
    $line | Out-File -FilePath $LogPath -Append -Encoding UTF8
}

function Get-TargetProcess {
    Get-CimInstance Win32_Process -Filter "Name = '$processFile'" |
        Where-Object { $_.ExecutablePath -eq $ExePath }
}

function Start-TargetProcess {
    try {
        $startParams = @{
            FilePath = $ExePath
            WorkingDirectory = $WorkingDirectory
            PassThru = $true
        }

        if ($ArgumentList.Count -gt 0) {
            $startParams.ArgumentList = $ArgumentList
        }

        $started = Start-Process @startParams
        Write-MonitorLog "Start command succeeded. PID=$($started.Id) Path=$ExePath"

        Start-Sleep -Seconds $StartupGraceSeconds
        $verified = @(Get-TargetProcess)

        if ($verified.Count -eq 0) {
            throw "The process stopped within ${StartupGraceSeconds}s after startup."
        }

        $pids = ($verified | Select-Object -ExpandProperty ProcessId) -join ","
        Write-MonitorLog "Startup verified. PID=$pids"
        return $true
    }
    catch {
        Write-MonitorLog "Restart failed. Error=$($_.Exception.Message)"
        return $false
    }
}

$lastRestartAt = [datetime]::MinValue
$lastState = ""
$restartHistory = [System.Collections.Generic.Queue[datetime]]::new()

try {
    Write-MonitorLog "Monitor started. Target=$ExePath Interval=${IntervalSeconds}s MaxRestarts=$MaxRestarts/${RestartWindowMinutes}min"

    while ($true) {
        try {
            $now = Get-Date
            $windowStart = $now.AddMinutes(-$RestartWindowMinutes)

            while ($restartHistory.Count -gt 0 -and $restartHistory.Peek() -lt $windowStart) {
                [void]$restartHistory.Dequeue()
            }

            $processes = @(Get-TargetProcess)

            if ($processes.Count -gt 0) {
                $pids = ($processes | Select-Object -ExpandProperty ProcessId) -join ","
                if ($lastState -ne "RUNNING") {
                    Write-MonitorLog "Process is running. PID=$pids"
                    $lastState = "RUNNING"
                }
            }
            else {
                $secondsSinceRestart = ($now - $lastRestartAt).TotalSeconds

                if ($restartHistory.Count -ge $MaxRestarts) {
                    if ($lastState -ne "LIMIT_REACHED") {
                        Write-MonitorLog "Restart limit reached. Attempts=$($restartHistory.Count) Window=${RestartWindowMinutes}min"
                        $lastState = "LIMIT_REACHED"
                    }
                }
                elseif ($secondsSinceRestart -lt $RestartCooldownSeconds) {
                    if ($lastState -ne "COOLDOWN") {
                        Write-MonitorLog "Process is stopped, but restart is in cooldown."
                        $lastState = "COOLDOWN"
                    }
                }
                else {
                    Write-MonitorLog "Process is stopped. Restarting..."
                    $lastRestartAt = Get-Date
                    $restartHistory.Enqueue($lastRestartAt)

                    if (Start-TargetProcess) {
                        $lastState = "RESTARTED"
                    }
                    else {
                        $lastState = "RESTART_FAILED"
                    }
                }
            }
        }
        catch {
            Write-MonitorLog "Monitoring check failed. Error=$($_.Exception.Message)"
            $lastState = "MONITOR_ERROR"
        }

        Start-Sleep -Seconds $IntervalSeconds
    }
}
finally {
    if ($createdNew) {
        $mutex.ReleaseMutex()
    }
    $mutex.Dispose()
    Write-MonitorLog "Monitor stopped."
}

.\monitor-process.ps1 `
  -ExePath "C:\Apps\ReportTool\ReportTool.exe" `
  -WorkingDirectory "C:\Apps\ReportTool" `
  -ArgumentList @("--config", "C:\Apps\ReportTool\prod.json") `
  -IntervalSeconds 60 `
  -RestartCooldownSeconds 300 `
  -MaxRestarts 3 `
  -RestartWindowMinutes 60 `
  -StartupGraceSeconds 10 `
  -LogPath "C:\Logs\report-tool-monitor.log"

プログラム:
powershell.exe

引数:
-NoProfile -ExecutionPolicy Bypass -File "C:\Scripts\monitor-process.ps1" -ExePath "C:\Apps\SampleApp\SampleApp.exe" -WorkingDirectory "C:\Apps\SampleApp" -LogPath "C:\Logs\sampleapp-monitor.log"

開始:
C:\Scripts

$today = Get-Date -Format "yyyyMMdd"
$LogPath = "C:\Logs\process-monitor-$today.log"

2026-06-09 09:00:00 Monitor started. Target=C:\Apps\SampleApp\SampleApp.exe Interval=60s MaxRestarts=3/60min
2026-06-09 09:01:00 Process is stopped. Restarting...
2026-06-09 09:01:00 Start command succeeded. PID=1234 Path=C:\Apps\SampleApp\SampleApp.exe
2026-06-09 09:01:10 Startup verified. PID=1234
2026-06-09 10:15:00 Restart failed. Error=The process stopped within 10s after startup.
2026-06-09 10:25:00 Restart limit reached. Attempts=3 Window=60min

$targets = @(
    @{
        ExePath = "C:\Apps\AppA\AppA.exe"
        WorkingDirectory = "C:\Apps\AppA"
        LogPath = "C:\Logs\appa-monitor.log"
    },
    @{
        ExePath = "C:\Apps\AppB\AppB.exe"
        WorkingDirectory = "C:\Apps\AppB"
        LogPath = "C:\Logs\appb-monitor.log"
    }
)

foreach ($target in $targets) {
    .\monitor-process.ps1 @target
}

$targets = @(
    @{ Name = "AppA"; ExePath = "C:\Apps\AppA\AppA.exe"; WorkingDirectory = "C:\Apps\AppA" },
    @{ Name = "AppB"; ExePath = "C:\Apps\AppB\AppB.exe"; WorkingDirectory = "C:\Apps\AppB" }
)

while ($true) {
    foreach ($target in $targets) {
        # 対象ごとに Get-CimInstance で存在確認し、
        # 停止していれば Start-Process する
    }

    Start-Sleep -Seconds 60
}