Skip to content
BranchesTags

Repository files navigation

IIS Monitor

Enterprise-Grade IIS Health Monitoring & Auto-Recovery

Lightweight · Real-Time · Zero Dependency on .NET 4.5+

License .NET 4.0 Platform IIS Tests Release

Table of Contents

Why IIS Monitor?

Running IIS on legacy Windows Server environments shouldn't mean sacrificing observability. IIS Monitor fills the gap where modern monitoring tools can't reach — it targets .NET Framework 4.0, runs natively on Windows Server 2008 R2 SP1, and requires no external dependencies beyond the IIS management API that's already on your server.

Problem Solution
IIS app pools silently crash at 3 AM Automatic detection & recovery with configurable thresholds
No visibility into worker process memory/connection leaks Real-time app pool performance dashboard
Legacy servers can't run .NET 4.5+ monitoring tools Built for .NET 4.0 — runs everywhere IIS runs
Recovery actions cause cascading failures Smart backoff prevents restart storms
Need to check multiple servers manually Centralized dashboard with tray icon health indicators

Features

Core Monitoring Engine

  • App Pool Health Check — Detects Stopped / Started / Unknown states via Microsoft.Web.Administration
  • HTTP/HTTPS Availability — Deep health checks with keyword matching and configurable timeouts
  • 9 Recovery Strategies — From gentle app pool recycling to full IIS restart cascades
  • Failure Threshold — Require N consecutive failures before triggering recovery (avoids false positives)
  • Recovery Backoff — Max 3 recoveries per 5 minutes per target, preventing restart storms

App Pool Performance Dashboard

Real-time metrics for every application pool on the server:

Metric Source Description
Worker Process PID ServerManager.WorkerProcesses Active worker process IDs
Memory (MB) Process.WorkingSet64 Total working set memory per pool
Active Requests W3SVC_W3WP Counter Current in-flight requests
Requests/sec W3SVC_W3WP Counter Request throughput
Queue Length ASP.NET Counter Pending request queue depth

Auto-refreshes every 10 seconds. Manual refresh button available. Idle pools show "Idle (no requests)" instead of misleading zeros.

Observability & Alerts

  • Live Health Chart — Real-time line chart for CPU / Memory / Disk usage trends
  • SMTP Email Alerts — Configurable SMTP server, recipients, and subject templates
  • Webhook Alerts — POST JSON payloads to Slack, Teams, DingTalk, or custom endpoints
  • Alert Cooldown — Prevents notification floods during sustained outages
  • CSV & HTML Reports — Export historical health data for offline analysis

User Experience

  • Dual-Tab Layout — Switch between monitoring logs and app pool performance at a glance
  • Dark Mode — Full dark theme with persistent preference
  • System Tray — Green / Yellow / Red icon reflects overall health status
  • Auto-Minimize — Minimize to tray on monitoring start
  • Quick Select — Pick sites and app pools directly from local IIS configuration
  • Double-Click Test — Instantly test any site or app pool by double-clicking its row

Architecture

┌─────────────────────────────────────────────────────────┐
│                      MainForm (UI)                       │
│  ┌──────────┐  ┌──────────┐  ┌────────────────────────┐ │
│  │ Tab: Logs │  │Tab: Pools│  │   Health Chart (Live)  │ │
│  └──────────┘  └──────────┘  └────────────────────────┘ │
└─────────────┬───────────────────────────┬───────────────┘
              │ Events                    │ Events
┌─────────────▼───────────────────────────▼───────────────┐
│                   MonitorService                         │
│  ┌─────────────┐  ┌──────────────┐  ┌────────────────┐  │
│  │ HealthCheck  │  │ResourceMonitor│  │ MetricsTimer   │  │
│  │ (Timer)      │  │ (CPU/Mem/Disk)│  │ (10s interval) │  │
│  └──────┬──────┘  └──────────────┘  └───────┬────────┘  │
│         │                                    │           │
│  ┌──────▼────────────────────────────────────▼────────┐  │
│  │                   IISHelper                         │  │
│  │  • ServerManager API  • PerformanceCounters         │  │
│  │  • App Pool CRUD      • HTTP Health Checks          │  │
│  │  • Worker Process     • IIS Restart                 │  │
│  └─────────────────────────────────────────────────────┘  │
└──────────────────────────────────────────────────────────┘
              │
┌─────────────▼──────────────────────────────────────────┐
│                   Infrastructure                         │
│  ┌──────────┐  ┌─────────────┐  ┌────────────────────┐ │
│  │  Logger   │  │ AlertService│  │  ReportExporter    │ │
│  │ (Async)   │  │ (SMTP/Hook) │  │  (CSV / HTML)     │ │
│  └──────────┘  └─────────────┘  └────────────────────┘ │
└─────────────────────────────────────────────────────────┘

Key Design Decisions:

  • Zero external process dependencies — Uses Microsoft.Web.Administration API directly, no PowerShell or appcmd.exe calls
  • Async logging — BlockingCollection<T> + dedicated writer thread, never blocks the monitoring loop
  • Thread-safe counters — ConcurrentDictionary for failure tracking across timer callbacks
  • PerformanceCounter dual-sampling — Rate counters (NextValue()) require two samples; handled automatically with configurable sleep intervals

Quick Start

Prerequisites

Requirement Version
Windows Server 2008 R2 SP1 or later
.NET Framework 4.0 Runtime
IIS 7.0 or later
Permissions Administrator (required for IIS management)

Build & Run

# Clone
git clone https://github.com/xuu1998/IISMonitor.git
cd IISMonitor

# Build (NuGet packages auto-restore)
dotnet build IISMonitor\IISMonitor.csproj -c Release

# Run as Administrator
IISMonitor\bin\Release\IISMonitor.exe

First Run

  1. Click "从本机选站点" / "从本机选应用池" to import IIS configuration
  2. Set check interval (default: 5 seconds) and failure threshold (default: 2)
  3. Choose a restart strategy from the dropdown
  4. Click "启动监控"
  5. (Optional) Enable "启动时自动监控" for hands-free operation

Configuration

Configuration is auto-saved to MonitorConfig.xml on first run.

File Location Purpose
MonitorConfig.xml App directory Runtime configuration
logs\IISMonitor_YYYYMMDD.log logs\ Daily rotating logs (10MB max, 30-day retention)
logs\health_results.jsonl logs\ Structured health check data (for report export)

Restart Strategies

Choose the recovery approach that matches your tolerance for downtime vs. impact:

Strategy Impact When to Use
AppPoolOnly Minimal — recycles single pool Default for most scenarios
AppPoolRecycleOnly Minimal — graceful recycle When you want soft recycling only
SiteRestartOnly Low — restarts single site When pool recycling isn't enough
AppPoolThenIIS Medium — escalates to full IIS When pool issues persist
AppPoolThenSite Low-Medium — tries pool first Balanced escalation
SiteThenAppPool Low-Medium — tries site first When site config is the issue
SiteThenIIS Medium — escalates to full IIS When site restart isn't enough
IISOnly High — affects ALL sites Last resort, server-level issues
All High — tries everything Maximum recovery coverage

Warning: IISOnly and All strategies will briefly interrupt all websites on the server. Use with caution in production.

Performance Monitoring

The App Pool Performance tab provides real-time visibility into worker process behavior:

┌─────────────────────────────────────────────────────────────┐
│  [Refresh]                                                    │
├──────────┬───────┬──────┬─────────┬──────────┬───────┬──────┤
│ App Pool │  PID  │ WPs  │ Mem(MB) │ Active   │ Req/s │Queue │
├──────────┼───────┼──────┼─────────┼──────────┼───────┼──────┤
│ Default  │ 1234  │  1   │   128.5 │     5    │  12.3 │   0  │
│ ApiPool  │ 5678  │  2   │   256.0 │    42    │  87.1 │   0  │
│ AppPool2 │   -   │  0   │     -   │     -    │   -   │   -  │
│ AppPool3 │ 9012  │  1   │    64.2 │     0    │   0.0 │   0  │
└──────────┴───────┴──────┴─────────┴──────────┴───────┴──────┘
  • Auto-refresh every 10 seconds (independent of health check interval)
  • Manual refresh via button for on-demand snapshots
  • "-" indicates the pool is idle (no active worker process) or stopped
  • Performance counters use dual-sampling to handle rate-based metrics correctly

Project Structure

IISMonitor/
├── IISMonitor/
│   ├── Models/
│   │   ├── HealthRecord.cs           # Health check result model
│   │   └── AppPoolMetrics.cs         # App pool performance snapshot
│   ├── Services/
│   │   ├── ResourceMonitor.cs        # CPU/Memory/Disk monitoring
│   │   └── AlertService.cs           # SMTP & Webhook alerting
│   ├── Export/
│   │   └── ReportExporter.cs         # CSV & HTML report generation
│   ├── UI/
│   │   └── HealthChart.cs            # LiveCharts2 real-time chart
│   ├── Infrastructure/
│   │   ├── ThemeManager.cs           # Light/Dark theme engine
│   │   └── EnumExtensions.cs         # Enum Description attribute helpers
│   ├── libs/                         # Vendored DLLs (MWA, Newtonsoft.Json)
│   ├── MainForm.cs                   # Main window logic & event wiring
│   ├── MainForm.Designer.cs          # WinForms layout (auto-generated)
│   ├── MonitorService.cs             # Core monitoring loop & orchestration
│   ├── MonitorConfig.cs              # Configuration model & XML persistence
│   ├── IISHelper.cs                  # IIS API wrapper (ServerManager + Counters)
│   └── Logger.cs                     # Async file logger with rotation
├── IISMonitor.Tests/                 # Unit tests (26 tests)
├── LICENSE                           # MIT License
└── README.md

FAQ

Q: Why target .NET 4.0 instead of a newer framework?

Many enterprise Windows Server 2008 R2 environments cannot upgrade to .NET 4.5+. By targeting .NET 4.0, IIS Monitor runs on the widest range of servers without requiring framework upgrades.

Q: Why are performance counters showing zeros?

Rate-based counters (like Total Requests/Sec) require two samples to calculate. IIS Monitor handles this with automatic dual-sampling. If values are still zero, the app pool may be idle (no active worker process) — check the "PID" column for "-".

Q: Can I run this as a Windows Service?

The current version is a WinForms application with system tray support. For unattended server operation, enable "启动时自动监控" + "启动时最小化" in settings, and configure a Windows Task Scheduler entry to run at logon.

Q: Does it support remote IIS servers?

Not yet. IIS Monitor uses Microsoft.Web.Administration which operates on the local IIS instance. For remote monitoring, deploy an instance on each server.

Contributing

Contributions are welcome! Please open an issue first to discuss what you'd like to change.

  1. Fork the repository
  2. Create a feature branch (git checkout -b feature/amazing-feature)
  3. Commit your changes (git commit -m 'Add amazing feature')
  4. Push to the branch (git push origin feature/amazing-feature)
  5. Open a Pull Request

License

This project is licensed under the MIT License — see the LICENSE file for details.

You are free to use, modify, and distribute this software for any purpose, including commercial use.

About

轻量级 IIS 健康监控与自动恢复工具，支持应用池性能实时监控，兼容 Windows Server 2008+ / .NET 4.0

Resources

Readme
MIT license
Activity

Stars

0 stars

Watchers

0 watching

Forks

0 forks
Report repository

Releases

Packages

Contributors

Languages