PowerShell script to fire some URLs to get them warmed up

ec2_web_heater.ps1

param (
    [string] $NamePattern = "Dummy-web-app-*",
    [int] $Iterations = 2
)

function Get-WebInstances () {
  $res = $(aws ec2 describe-instances --region us-east-1 --filters  "Name=tag:Name,Values=$NamePattern")
  $json = $res | ConvertFrom-Json
  $instances = $json.Reservations.Instances `
                  | Where-Object { $_.State.Name -eq "Running" } `
                  | Select-Object PublicDnsName, `
                                  @{Label="Tags"; Expression={$_.Tags | Where-Object { $_.Key -eq "Name"}}}
  return $instances
}

function Get-WebInstanceUris($WebDnss) {
    $uris = @()
    foreach ($web_dns in $WebDnss) {
        $uris += "http://${web_dns}:8000"
    }  
    return $uris
}

function Request-PrinterPage($Uri) {
    $targets = @("/some/damn/eager/resource",
                 "/other/damn/eager/resource")

    foreach ($target in $targets) {
        $targetUri = $uri + $target
        $res = Invoke-WebRequest -Uri $targetUri
        $status = $res.StatusCode
        "- ${targetUri} (${status})"
    }
    ""
}

function Request-NPrinterPage($Uris) {
    foreach ($uri in $Uris) {
        Request-PrinterPage -Uri $uri
    }
}

###

"Warming up web server intances..."
"- NamePattern: $NamePattern"

$web_instances = Get-WebInstances
""

$web_dnss = $web_instances.PublicDnsName
$web_uris = Get-WebInstanceUris -WebDnss $web_dnss
if (!$web_uris) {
    "Failed to infer Web instances URI from pattern"
    exit
}

for ($i = 1; $i -lt ($Iterations + 1); $i++) {
    "Iteration ${i}:"
    Request-NPrinterPage -Uris $web_uris
}

"Fairly warm!"