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Health checks and process supervision on Windows

Verified 1 min read

Design liveness vs readiness endpoints, supervise Node/Python/Go services, and tune IIS app-pool ping/rapid-fail without crash loops.

Tested onStandard / Datacenter · Build 26100.33650 · x64
E1
Build
26100.33650
Edition
Standard / Datacenter
Architecture
x64
Support
Documentation (E1)
Evidence
E1Official documentation
Verified
2026-10-29
Page type
Task

The short answer

Section titled “The short answer”

Two different checks:

  • Liveness — is the process alive? Restart if not.
  • Readiness — can it serve? Remove from the proxy if not.

Do not use one endpoint for both. A readiness check that hits the database will fail during a DB outage and cause a restart loop that makes it worse.

Endpoints

Section titled “Endpoints”
  • /healthz — process alive, no dependencies; cheap.
  • /readyz — can serve: DB/cache/storage with short timeouts; returns 503 when not ready.
  • Never expose internal details (versions, connection strings) publicly; restrict to localhost/proxy.

IIS app pool

Section titled “IIS app pool”
  • Ping: PingEnabled, PingInterval (default 30s), PingResponseTime.
  • Rapid-fail protection: RapidFailProtection, RapidFailProtectionMaxCrashes (default 5 in 5 min). When tripped, the pool stops — a good safety valve, but it means “down until fixed”.
  • Start mode: OnDemand vs AlwaysRunning; AlwaysRunning + preload for latency-sensitive sites.
  • Idle timeout: disabling keeps the app warm but hides leaks; monitor.
Terminal window
Get-ItemProperty IIS:\AppPools\apppool | Select-Object name,startMode,processModel

Windows services

Section titled “Windows services”
  • NSSM/WinSW onfailure restart with a delay (10s+), not an instant loop.
  • Set a restart throttle/limit so a permanently broken app does not spin forever.
  • Log the exit code; restart without a reason is not a fix.

Proxy health

Section titled “Proxy health”
  • Nginx OSS: passive checks (max_fails, fail_timeout); active checks are in NGINX Plus.
  • ARR farm: health test path + interval.
  • Remove a failing node from rotation; alert on repeated failures.

Verify

Section titled “Verify”
Terminal window
curl.exe -I http://127.0.0.1:3000/healthz
curl.exe -I http://127.0.0.1:3000/readyz
Get-IISAppPool apppool | Select-Object Name,State
Get-WinEvent -LogName Application -MaxEvents 20 | Where-Object ProviderName -match 'Application Error'

Lab boundary

Section titled “Lab boundary”

E1. The lab did not configure app-pool ping/rapid-fail or a watchdog; the settings are the production design for Server 2025.

Sources