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

Inherits:
Kube::Cluster::Manifest::Middleware show all
Defined in:
lib/kube/cluster/manifest/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"

Constants inherited from Kube::Cluster::Manifest::Middleware

CLUSTER_SCOPED_KINDS, POD_BEARING_KINDS

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/manifest/middleware/hpa_for_deployment.rb', line 26

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

Instance Method Details

#call(resource) ⇒ Object 



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# File 'lib/kube/cluster/manifest/middleware/hpa_for_deployment.rb', line 31

def call(resource)
  return resource unless pod_bearing?(resource)

  value = label(resource, LABEL)
  return resource 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 = kind(resource)

  # 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

  hpa = Kube::Schema["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 },
        },
      },
    ]
  }

  [resource, hpa]
end