k8s-resourcequotas.sh

# the following will demonstrate how combined CPU requirements
# can stop a pod from being scheduled inside a given namespace

# create the manifest.yaml file shown below
# note the pod, named combo, is built from a pair of containers (nginx and redis)
cat > ./manifest.yaml << EOF
apiVersion: v1
kind: Namespace
metadata:
  name: rqtest
---
apiVersion: v1
kind: ResourceQuota
metadata:
  name: rqtest
  namespace: rqtest
spec:
  hard:
    requests.cpu: 1
    requests.memory: 1Gi
    limits.cpu: 2
    limits.memory: 2Gi
---
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: combo
  name: combo
  namespace: rqtest
spec:
  replicas: 1
  selector:
    matchLabels:
      app: combo
  template:
    metadata:
      creationTimestamp: null
      labels:
        app: combo
    spec:
      containers:
      - image: nginx
        name: nginx
        resources:
          requests:
            cpu: 550m
            memory: 500Mi
          limits:
            cpu: 600m
            memory: 600Mi
      - image: redis
        name: redis
        resources:
          requests:
            cpu: 500m
            memory: 500Mi
          limits:
            cpu: 600m
            memory: 600Mi
EOF

# create the resources and observe how the pod is not scheduled
kubectl apply -f manifest.yaml
kubectl get all -k rqtest

# why is this?
# the requests.cpu setting inside the nginx container is 550m (NOTE: slightly oversized!)
# the requests.cpu setting inside the redis container is 500m
# 550m+500m exceeds the hard "requests.cpu: 1" setting in the ResourceQuota object for the namespace

# slim down the nginx requests.cpu setting ...
sed -i "s/550/500/g" manifest.yaml

# ... and try again to see the pod getting scheduled
kubectl apply -f manifest.yaml
kubectl get all -n rqtest