IT-SDK-Kubernetes-Basics

Ref.

• https://kind.sigs.k8s.io/
• http://kubernetesbyexample.com/
• https://kubernetes.io/docs/reference/kubectl/cheatsheet/

Fast-Run

kubectl run  --image=nginx -o yaml --dry-run=client > pod-defination.yaml
kubectl create deployment --image=nginx --replicas=3 -o yaml --dry-run=client > deployment-defination.yaml

ServiceTypes

• ref: https://kubernetes.io/docs/concepts/services-networking/service/
• ClusterIP: Service is reachableonly from within the cluster.
• NodePort: Service is reachable from outside the cluster.
• LoadBalancer: Service is reachable from outside the cluster (Using a cloud provider's load balancer).
• ExternalName: t.b.d.

Probes

• ref: https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/

Bedeutung

• Probe: describes a health check to be performed against a container to determine whether it is alive or ready to receive traffic.
• Liveness: to know when to restart a container.
• Readiness: to know when a container is ready to start accepting traffic.
• Startup: to know when a container application has started. If such a probe is configured, it disables liveness and readiness checks until it succeeds.

Settings

• initialDelaySeconds: wait x seconds before performing the first probe.
• periodSeconds: every x seconds to perform probe.
• timeoutSeconds: wait x seconds after which the probe times out.
• successThreshold: x times to considered successful after having failed (Defaults=1).
• failureThreshold: x times to giving up after fails (Defaults=3). Giving up in case of liveness probe means restarting the container.

kind

• https://kind.sigs.k8s.io/docs/user/quick-start/#installation

curl -Lo ./kind https://kind.sigs.k8s.io/dl/v0.11.1/kind-linux-amd64
curl -Lo kind.exe https://kind.sigs.k8s.io/dl/v0.11.1/kind-windows-amd64

kind create cluster
kind create cluster --name kind-2
kind get clusters
kind delete cluster
...
kubectl cluster-info --context kind-kind

minikube

• https://minikube.sigs.k8s.io/docs/

minikube start
minikube dashboard
minikube stop		            #Halt the cluster:
minikube config set memory 16384    #Set memory limit
minikube addons list	            #Browse the catalog
minikube start -p aged --kubernetes-version=v1.16.1		#Create a second cluster
minikube delete --all		    #Delete all of the minikube