Quick Start

This guide creates a policy that right-sizes Deployments in a staging namespace using the p95 of the last 7 days of data.

1. Install k8s-sustain

helm repo add k8s-sustain https://noony.github.io/k8s-sustain
helm repo update
helm install k8s-sustain k8s-sustain/k8s-sustain \
  --namespace k8s-sustain \
  --create-namespace

2. Create a Policy

staging-policy.yaml

apiVersion: k8s.sustain.io/v1alpha1
kind: Policy
metadata:
  name: staging-rightsizing
spec:
  update:
    types:
      deployment: Ongoing       # controller recycles stale pods; webhook injects resources
  rightSizing:
    resourcesConfigs:
      cpu:
        window: 168h            # 7-day lookback
        requests:
          percentile: 95
          headroom: 10  # +10% safety buffer
        limits:
          keepLimitRequestRatio: true
      memory:
        window: 168h
        requests:
          percentile: 95
          headroom: 20
        limits:
          keepLimitRequestRatio: true

kubectl apply -f staging-policy.yaml

3. Opt in a Deployment

Add the annotation to the pod template of any Deployment you want right-sized:

kubectl patch deployment my-app -n staging \
  --type=json \
  -p='[{"op":"add","path":"/spec/template/metadata/annotations","value":{"k8s.sustain.io/policy":"staging-rightsizing"}}]'

Or add it directly in the Deployment manifest:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
  namespace: staging
spec:
  template:
    metadata:
      annotations:
        k8s.sustain.io/policy: staging-rightsizing  # (1)!
    spec:
      containers:
        - name: app
          image: my-app:latest

1. This annotation tells k8s-sustain which policy governs this workload.

4. Wait for data

Cold start

Recording rules need at least one evaluation cycle (~1 minute) before data is available. For meaningful percentile recommendations, allow data to accumulate for at least a few hours. The operator logs no metrics yet, skipping for workloads with no data yet.

5. Check the Policy status

kubectl get policy staging-rightsizing -o yaml

Look for the Ready condition:

status:
  conditions:
    - type: Ready
      status: "True"
      reason: ReconciliationSucceeded
      message: All targeted workloads have been processed.

6. Verify resource changes

kubectl get deployment my-app -n staging \
  -o jsonpath='{.spec.template.spec.containers[*].resources}'

The controller reconciles on a fixed 10m interval by default. To see changes sooner during testing, run the controller locally with --reconcile-interval=2m (see CLI Reference).

Next steps

• Use OnCreate mode to inject resources at pod creation without restarting existing pods → Update Modes
• Enable in-place updates for zero-restart resource changes on k8s ≥ 1.31 → In-Place Updates
• Right-size CronJobs → CronJob guide