Resource requests and limits

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Goal

Add CPU and memory requests and limits to the web container so the Kubernetes scheduler can place it correctly and it cannot consume unbounded resources.

Why

• Requests — the amount of CPU/memory the pod is guaranteed. The scheduler uses this to decide which node can host the pod.
• Limits — the maximum the container is allowed to use. A container that exceeds its memory limit is OOM-killed; one that exceeds its CPU limit is throttled.

Without requests, the scheduler treats every pod as if it needs zero resources and may overcommit nodes. Without limits, one runaway container can starve its neighbours.

Step 1 — Add resources to deployment.yaml

Open deployment.yaml and add a resources block to the container spec (after the probes added in the previous page):

apiVersion: apps/v1
kind: Deployment
metadata:
  name: web
spec:
  replicas: 1
  selector:
    matchLabels:
      app: web
  template:
    metadata:
      labels:
        app: web
    spec:
      containers:
        - name: nginx
          image: nginx:1.27
          ports:
            - containerPort: 80
          env:
            - name: GREETING
              valueFrom:
                configMapKeyRef:
                  name: web-config
                  key: GREETING
          readinessProbe:
            httpGet:
              path: /
              port: 80
            initialDelaySeconds: 2
            periodSeconds: 5
          livenessProbe:
            httpGet:
              path: /
              port: 80
            initialDelaySeconds: 5
            periodSeconds: 10
          resources:
            requests:
              cpu: "50m"
              memory: "64Mi"
            limits:
              cpu: "200m"
              memory: "128Mi"

Apply:

kubectl apply -f deployment.yaml

Step 2 — Verify

Describe a pod to confirm the limits appear:

kubectl describe pod -l app=web | grep -A4 Limits

Expected output:

    Limits:
      cpu:     200m
      memory:  128Mi
    Requests:
      cpu:     50m
      memory:  64Mi

Checkpoint

The web Deployment now has resource budgets. The scheduler places pods on nodes that have at least 50m CPU and 64Mi memory free, and containers that try to exceed 128Mi memory will be restarted.

Next: 05 Rolling update