New-OctopusApiKey.ps1

$octopusUrl = 'https://samples.octopus.app'
$username = 'admin'
$password = 'your-password'

$loginPath = "$octopusUrl/api/users/login"

$response = Invoke-WebRequest -Method Post `
    -Uri $loginPath `
    -Body (@{'Username' = $username;'Password' = $password} | ConvertTo-Json) `
    -UseBasicParsing `
    -SessionVariable 'session'

$userId = ($response.Content | ConvertFrom-Json).Id
$csrfToken = $session.Cookies.GetCookies($loginPath) `
    | Where-Object { $_.Name.StartsWith('Octopus-Csrf-Token') }
$sessionToken = $session.Cookies.GetCookies($loginPath) `
    | Where-Object { $_.Name.StartsWith('OctopusIdentificationToken') }

$headers = @{
    'Cookie' = $sessionToken.Name + '=' + $sessionToken.Value
    'X-Octopus-Csrf-Token' = $csrfToken.Value
}

Invoke-RestMethod -Method Post `
    -Uri "$octopusUrl/api/users/$userId/apikeys" `
    -Headers $headers `
    -Body (@{'Purpose'='Automation'} | ConvertTo-Json)