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Azure SignalR Service AutoScale Powershell Azure Function
{
"bindings": [
{
"name": "Timer",
"type": "timerTrigger",
"direction": "in",
"schedule": "0 */5 * * * *"
}
]
}
{
"IsEncrypted": false,
"Values": {
"AzureWebJobsStorage": "UseDevelopmentStorage=true",
"FUNCTIONS_WORKER_RUNTIME": "powershell",
"ServicePrincipalClientId": "{YOUR_SERVICE_PRINCIPAL_CLIENT_ID}",
"ServicePrincipalKey": "{YOUR_SERVICE_PRINCIPAL_KEY}",
"ServicePrincipalTenantId": "{YOUR_SERVICE_PRINCIPAL_TENANT_ID}",
"SignalRResourceId": "{YOUR_SIGNALR_SERVICE_RESOURCE_ID}"
}
}
# Input bindings
param($Timer)
# Variable definitions
$resourceId = $env:SignalRResourceId
$connectionsPerUnit = 1000 # Number of concurent connections you can have per unit
$unitCounts = 1,2,5,10,20,50,100 # Supported SignalR Unit Counts
$scaleThreshold = .95 # Percentage threshold at which to scale
# Authenticate the service principle
$clientId = $env:ServicePrincipalClientId
$key = $env:ServicePrincipalKey
$securePassword = ConvertTo-SecureString $key -AsPlainText -Force
$credentials = New-Object System.Management.Automation.PSCredential($clientId, $securePassword)
$tenantId = $env:ServicePrincipalTenantId
Connect-AzAccount -ServicePrincipal -Credential $credentials -Tenant $tenantId
# Get information about the current resource state
$signalRResource = Get-AzResource -ResourceId $resourceId -Verbose
$currentUnitCount = [int]$signalRResource.Sku.Capacity
# Only scale if we are on the Standard_S1 plan
if ($signalRResource.Sku.Name -eq "Standard_S1") {
# Get metrics for the last 5 minutes
$connectionCountMetric = Get-AzMetric -ResourceId $resourceId -MetricName "ConnectionCount" -TimeGrain 00:05:00 -StartTime (Get-Date).AddMinutes(-5) -AggregationType Maximum
$maxConnectionCount = $connectionCountMetric.Timeseries.Data[0].Maximum
# Calculate the target unit count
$targetUnitCount = 1
foreach ($unitCount in $unitCounts) {
$unitCountConnections = $unitCount * $connectionsPerUnit
$unitCountConnectionsThreshold = $unitCountConnections * $scaleThreshold
if ($unitCountConnectionsThreshold -gt $maxConnectionCount -or $unitCount -eq $unitCounts[$unitCounts.Count - 1]) {
$targetUnitCount = $unitCount
Break
}
}
# See if we need to change the unit count
if ($targetUnitCount -ne $currentUnitCount) {
Write-Host "Scaling resource to unit count: " $targetUnitCount
# Change the resource unit count
$signalRResource.Sku.Capacity = $targetUnitCount
$signalRResource | Set-AzResource -Force
} else {
Write-Host "Not scaling as resource is already at the optimum unit count: " $currentUnitCount
}
} else {
Write-Host "Can't scale as resource is not on a scalable plan: " $signalRResource.Sku.Name
}
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