Server Limits

Fine‑tune resource & safety thresholds using Set-KrServerLimit.

Prerequisites: basic hosting in Endpoints and route basics in Routes.

Full source

File: pwsh/tutorial/examples/13.1-Server-Limits.ps1

<#
    13.1 Server Limits Example
    Demonstrates setting server limits for request body size, concurrent connections, and other limits.
    File:    13.1-Server-Limits.ps1
#>
param(
    [int]$Port = 5000,
    [IPAddress]$IPAddress = [IPAddress]::Loopback
)
# 1. (Optional) Logging pipeline so we see events
New-KrLogger |
    Set-KrLoggerLevel -Value Debug |
    Add-KrSinkConsole |
    Register-KrLogger -Name 'console' -SetAsDefault | Out-Null

# 2. Create server host
New-KrServer -Name 'Server Limits'

# 3. Add loopback listener on port 5000 (auto unlinks existing file if present)
# This listener will be used to demonstrate server limits configuration.
Add-KrEndpoint -Port $Port -IPAddress $IPAddress


# 5. Set server limits for request body size, concurrent connections, and other limits
Set-KrServerLimit -MaxRequestBodySize 1048576 -MaxConcurrentConnections 1 -KeepAliveTimeoutSeconds 60 -MaxRequestHeadersTotalSize 16384

# 6. Finalize configuration and set server limits
Enable-KrConfiguration

# 7. Map a simple info route to demonstrate server limits in action
Add-KrMapRoute -Verbs Get -Pattern '/info' -ScriptBlock {
    Start-Sleep 20
    Write-KrJsonResponse @{ status = 'ok'; time = (Get-Date) }
}

# 8. Start the server (runs asynchronously; press Ctrl+C to stop)
Start-KrServer

Step-by-step

  1. Create server + listener.
  2. Add runtime.
  3. Apply limits (here: body size, headers size, keep-alive, and MaxConcurrentConnections 1).
  4. Enable configuration (commits listeners + runtime + limits).
  5. Map a long-running /info route (includes Start-Sleep 20 to simulate work).
  6. Start server.

Common settings

Setting Why
MaxRequestBodySize Reject large uploads early
MaxConcurrentConnections Basic throttling
KeepAliveTimeoutSeconds Trim idle sockets
MaxRequestHeadersTotalSize Protect from header abuse
MinRequestBodyDataRate Drop very slow clients

Try it

Open two separate PowerShell terminals (or run jobs) and issue the request simultaneously to observe the single concurrent connection limit (second request ends early):

# Terminal 1 (holds the only allowed connection ~20s)
Invoke-WebRequest -Uri http://127.0.0.1:5000/info | Select-Object -ExpandProperty Content

# Quickly in Terminal 2 (while first still running)
Invoke-WebRequest -Uri http://127.0.0.1:5000/info

Expected:

  • First call returns JSON after ~20 seconds.
  • Second call fails fast with an error similar to:
Invoke-WebRequest: The response ended prematurely. (ResponseEnded)

(Exact wording may vary.) This demonstrates throttling via -MaxConcurrentConnections 1.

References

Troubleshooting

Symptom Cause Fix
Large upload rejected Limit too small Increase MaxRequestBodySize
Clients disconnect Data rate limits strict Relax Min*DataRate values
Slow responses Too few connections Raise MaxConcurrentConnections
Second request aborted MaxConcurrentConnections set to 1 Increase value or remove limit

See also: Endpoints · Logging

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