Gist to add HPA and PDB to Carvel Packages produced by TAP.

01-values.yaml

#@data/values
---
workload_name: jeremy
hpa: 
  enabled: true
  minReplicas: 5
  maxReplicas: 10
  metrics:
  - type: Resource
    resource:
      name: cpu
      target:
        type: Utilization
        averageUtilization: 10
  - type: Pods
    pods:
      metric:
        name: packets-per-second
      target:
        type: AverageValue
        averageValue: 1k
pdb:
  enabled: true
  minAvailable: 50%

02-pdb.yaml

#@ load("@ytt:data", "data")

#@ if hasattr(data.values, "pdb") and hasattr(data.values.pdb, "enabled") and data.values.pdb.enabled == True:
---
apiVersion: policy/v1
kind: PodDisruptionBudget
metadata:
  name: #@ data.values.workload_name + "-pdb"
spec:
  minAvailable: #@ data.values.pdb.minAvailable
  selector:
    matchLabels:
      app: #@ data.values.workload_name
      
#@ end

03-hpa.yaml

#@ load("@ytt:data", "data")

#@ if hasattr(data.values, "hpa") and hasattr(data.values.hpa, "enabled") and data.values.hpa.enabled == True:
---
apiVersion: kapp.k14s.io/v1alpha1
kind: Config
rebaseRules:
  - path: [spec, replicas]
    type: copy
    sources: [existing, new]
    resourceMatchers:
      - apiGroupKindMatcher: {apiGroup: apps, kind: Deployment}
---
apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: #@ data.values.workload_name 
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: #@ data.values.workload_name 
  minReplicas: #@ data.values.hpa.minReplicas
  maxReplicas: #@ data.values.hpa.maxReplicas
  metrics: #@ data.values.hpa.metrics
#@ end

04-schema.yaml

#@data/values-schema
---
#@schema/title "Workload name"
#@schema/example "tanzu-java-web-app"
#@schema/validation min_len=1
workload_name: ""

#@schema/title "Pod Disruption Budget"
#@schema/description "https://kubernetes.io/docs/tasks/run-application/configure-pdb/"
#@schema/nullable
pdb:
  #@schema/title "minAvailable"
  #@schema/description "the number of pods from that set that must still be available after the eviction, even in the absence of the evicted pod. minAvailable can be either an absolute number or a percentage. Default is 60%"
  #@schema/type any=True
  minAvailable: 60%
  #@schema/title "enabled"
  #@schema/description "Enabled PDB to be created if set to true. Default is false."
  enabled: false
  
#@schema/title "Horizontal Pod Autoscaler"
#@schema/description "https://kubernetes.io/docs/tasks/run-application/horizontal-pod-autoscale-walkthrough/"
#@schema/nullable
hpa:
  #@schema/title "minAvailable"
  #@schema/description "minReplicas is the lower limit for the number of replicas to which the autoscaler can scale down. Default is 1"
  minReplicas: 1
  #@schema/title "maxAvailable"
  #@schema/description "maxReplicas is the upper limit for the number of replicas to which the autoscaler can scale up. It cannot be less that minReplicas. Default is 5"
  maxReplicas: 5 
  #@schema/title "enabled"
  #@schema/description "Enabled HPA to be created if set to true. Default is false. Default is false."
  enabled: false
  #@schema/title "enabled"
  #@schema/description "metrics contains the specifications for which to use to calculate the desired replica count (the maximum replica count across all metrics will be used). Defaults to CPU at 80% utilization."
  #@schema/type any=True
  metrics:
  - type: Resource
    resource:
      name: cpu
      target:
        type: Utilization
        averageUtilization: 80

05-rbac.yaml

---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: pod-disruption-budgets
  labels:
    apps.tanzu.vmware.com/aggregate-to-deliverable: "true"
rules:
  - apiGroups: ["policy"]
    resources: ["poddisruptionbudgets"]
    verbs:
      - get
      - list
      - watch
      - create
      - patch
      - update
      - delete
      - deletecollection
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: horizontal-pod-autoscalers
  labels:
    apps.tanzu.vmware.com/aggregate-to-deliverable: "true"
rules:
  - apiGroups: ["autoscaling"]
    resources: ["horizontalpodautoscalers"]
    verbs:
      - get
      - list
      - watch
      - create
      - patch
      - update
      - delete
      - deletecollection