Class: Kube::Cluster::Middleware::HPAForDeployment

Inherits:
Kube::Cluster::Middleware show all
Defined in:
lib/kube/cluster/middleware/hpa_for_deployment.rb

Overview

Generates a HorizontalPodAutoscaler for every pod-bearing resource that carries the app.kubernetes.io/autoscale label.

The label value encodes the min and max replicas as “min-max”:

metadata.labels = { "app.kubernetes.io/autoscale": "1-5" }

Options:

cpu:    — target CPU utilization percentage (default: 75)
memory: — target memory utilization percentage (default: 80)

stack do
  use Middleware::HPAForDeployment
  use Middleware::HPAForDeployment, cpu: 60, memory: 70
end

Constant Summary collapse

LABEL = 
:"app.kubernetes.io/autoscale"

Instance Method Summary collapse

Constructor Details

#initialize(cpu: 75, memory: 80) ⇒ HPAForDeployment

Returns a new instance of HPAForDeployment.



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# File 'lib/kube/cluster/middleware/hpa_for_deployment.rb', line 25

def initialize(cpu: 75, memory: 80)
  @cpu = cpu
  @memory = memory
end

Instance Method Details

#call(manifest) ⇒ Object 



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# File 'lib/kube/cluster/middleware/hpa_for_deployment.rb', line 30

def call(manifest)
  generated = []

  manifest.resources.each do |resource|
    next unless resource.pod_bearing?

    value = resource.label(LABEL)
    next unless value

    min, max = parse_range(value)

    h = resource.to_h
    name      = h.dig(:metadata, :name)
    namespace = h.dig(:metadata, :namespace)
    labels    = h.dig(:metadata, :labels) || {}
    api_version = h[:apiVersion] || "apps/v1"
    resource_kind = resource.kind

    # Capture ivars as locals — the block runs via instance_exec
    # on a BlackHoleStruct, so @ivars would resolve on the BHS.
    cpu_target    = @cpu
    memory_target = @memory

    generated << Kube::Cluster["HorizontalPodAutoscaler"].new {
      metadata.name      = name
      metadata.namespace = namespace if namespace
      metadata.labels    = labels.reject { |k, _| k == LABEL }

      spec.scaleTargetRef = {
        apiVersion: api_version,
        kind:       resource_kind,
        name:       name,
      }
      spec.minReplicas = min
      spec.maxReplicas = max
      spec.metrics = [
        {
          type: "Resource",
          resource: {
            name: "cpu",
            target: { type: "Utilization", averageUtilization: cpu_target },
          },
        },
        {
          type: "Resource",
          resource: {
            name: "memory",
            target: { type: "Utilization", averageUtilization: memory_target },
          },
        },
      ]
    }
  end

  manifest.resources.concat(generated)
end