3. Playing with Containers

• Scaling your containers
• Updating live containers
• Forwarding container ports
• Ensuring flexible usage of your containers
• Submitting Jobs on Kubernetes
• Working with configuration files

Scaling your containers

cat << EOF > 3-1-1_deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-nginx
spec:
  replicas: 2
  selector:
    matchLabels:
      service : nginx
  template:
    metadata:
      labels:
        service : nginx
    spec:
      containers:
        - name: my-container
          image: nginx
---
apiVersion: v1
kind: Service
metadata:
  name: my-nginx
spec:
  ports:
    - protocol: TCP
      port: 80
      nodePort: 30080
  type: NodePort
  selector:
    service: nginx
EOF

kubectl create -f 3-1-1_deployment.yaml
deployment.apps "my-nginx" created
service "my-nginx" created

kubectl get pods
NAME                       READY     STATUS    RESTARTS   AGE
my-nginx-f465f5465-nsdxg   1/1       Running   0          1m
my-nginx-f465f5465-qm8xf   1/1       Running   0          1m

kubectl get services
NAME         TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)          AGE
kubernetes   ClusterIP   10.43.0.1       <none>        443/TCP          57m
my-nginx     NodePort    10.43.52.172    <none>        80:30080/TCP     1m

Horizontal Pod Autoscaler (HPA)

An HPA queries the source of metrics periodically and determines whether scaling is required by a controller based on the metrics it gets. There are two types of metrics that could be fetched; one is from Heapster, another is from RESTful client access. In the following example, we'll show you how to use Heapster to monitor Pods and expose the metrics to an HPA.

kubectl create -f https://raw.githubusercontent.com/kubernetes/kops/master/addons/monitoring-standalone/v1.7.0.yaml
deployment.extensions "heapster" created
service "heapster" created
serviceaccount "heapster" created
clusterrolebinding.rbac.authorization.k8s.io "heapster" created
role.rbac.authorization.k8s.io "system:pod-nanny" created
rolebinding.rbac.authorization.k8s.io "heapster-binding" created

kubectl get pods --all-namespaces | grep heapster
kube-system     heapster-574b644764-f9wxk                 2/2       Running     0          21s

kubectl get deployments
NAME       DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
my-nginx   2         2         2            2           1m

kubectl autoscale deployment my-nginx --cpu-percent=50 --min=2 --max=5
deployment.apps "my-nginx" autoscaled

cat << EOF > 3-1-2_hpa.yaml
apiVersion: autoscaling/v1
kind: HorizontalPodAutoscaler
metadata:
  name: my-nginx
spec:
  scaleTargetRef:
    kind: Deployment
    name: my-nginx
  minReplicas: 2
  maxReplicas: 5
  targetCPUUtilizationPercentage: 50
EOF

kubectl create -f 3-1-2_hpa.yaml
horizontalpodautoscaler.autoscaling "my-nginx" created

kubectl get hpa
NAME       REFERENCE             TARGETS         MINPODS   MAXPODS   REPLICAS   AGE
my-nginx   Deployment/my-nginx   <unknown>/50%   2         5         0          1m