Rolling Update

• update application without downtime
• default deployment strategy
• enable rollback

  kubectl rollout undo deployment [deployment-name]
  

Commands and Arguments

• specify commands and arguments for containers

spec:
  containers:
  - command: ["./start.sh"]
    args: ["--config", "/etc/myapp/config.yaml"]

Env

spec:
  containers:
  - env:
    - name: ENV_VAR_NAME
      value: "value1"

ConfigMap

• store configuration data

apiVersion: v1
kind: ConfigMap
metadata:
    name: my-configmap
data:
    CONFIG_KEY: "config_value"

spec:
  containers:
  - envFrom:
    - configMapRef:
        name: my-configmap

Secrets

• store sensitive data

  apiVersion: v1
  kind: Secret
  metadata:
      name: my-secret
  data:
      SECRET: "c2VjcmV0X3ZhbHVl" # base64 encoded
  

• how to base64 encode

  echo -n 'secret_value'
  c2VjcmV0X3ZhbHVl
  

• how to apply

  spec:
    containers:
    - envFrom:
      - secretRef:
          name: my-secret
  

Muntli-Container Pod

1. co-located containers

       apiVersion: v1
       kind: Pod
       metadata:
         name: multi-container-pod
       spec:
         containers:
         - name: app-container
           image: myapp:latest
         - name: sidecar-container
           image: log-collector:latest
   

2. init containers

       apiVersion: v1
       kind: Pod
       metadata:
         name: multi-container-pod
       spec:
         containers:
         - name: app-container
           image: myapp:latest
         initContainers:
         - name: init-app-container
           image: myapp:latest
   

3. sidecar containers

       apiVersion: v1
       kind: Pod
       metadata:
         name: multi-container-pod
       spec:
         containers:
         - name: app-container
           image: myapp:latest
         initContainers:
         - name: init-app-container
           image: myapp:latest
           restartPolicy: Always
   

HPA

• automatically scale the number of pods

  apiVersion: autoscaling/v2
  kind: HorizontalPodAutoscaler
  metadata:
    name: myapp-hpa
  spec:
    scaleTargetRef:
      apiVersion: apps/v1
      kind: Deployment
      name: myapp-deployment
    minReplicas: 2
    maxReplicas: 10
    metrics:
    - type: Resource
      resource:
        name: cpu
        target:
          type: Utilization
          averageUtilization: 50
  

VPA

• pre-install before VPA start

kubectl apply -f https://raw.githubusercontent.com/kubernetes/autoscaler/vpa-release-1.0/vertical-pod-autoscaler/deploy/vpa-v1-crd-gen.yaml
kubectl apply -f https://raw.githubusercontent.com/kubernetes/autoscaler/vpa-release-1.0/vertical-pod-autoscaler/deploy/vpa-rbac.yaml

• any container in the pod can be configured

apiVersion: autoscaling.k8s.io/v1
kind: VerticalPodAutoscaler
metadata:
  name: my-app-vpa
spec:
  targetRef:
    apiVersion: "apps/v1"
    kind: Deployment
    name: my-app
  updatePolicy:
    updateMode: "Recreate"  # Off, Initial, Recreate, InPlaceOrRecreate
  resourcePolicy:
    containerPolicies:
      - containerName: "application"
        minAllowed:
          cpu: 100m
          memory: 128Mi
        maxAllowed:
          cpu: 2
          memory: 2Gi
        controlledResources:
          - cpu
          - memory
        controlledValues: RequestsAndLimits

• tags :
• Cka