Kubernetes Review

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kubectl config set-context --current --namespace=alpha

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kubectl run nginx-pod --image=nginx:alpine --restart=Never --namespace=alpha

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kubectl create deploy webapp --image=nginx:alpine --replicas=3

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kubectl scale deploy webapp --replicas=1

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kubectl rollout history development webapp

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kubectl expose deploy/webapp --port=8080 --target-port=8080 --type=ClusterIP

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kubectl create role developer-role --resource=pods --verb=create,list,get,update,delete --namespace=delta

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kubectl create rolebinding developer-role-binding --role=developer-role --user=john --namespace=delta

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kubectl create clsuterrole dev-cluster-role --resource=developments --verb=create,list,get,update,delete

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kubectl create clusterrolebinding dev-cluster-role-binding --clusterrole=dev-cluster-role --user=john

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ETCDCTL_API=3 etcdctl --cacert=/etc/kubernetes/pki/etcd/ca.crt \
                      --cert=/etc/kubernetes/pki/etcd/server.crt \
                      --key=/etc/kubernetes/pki/etcd/server.key \
                      snapshot save /opt/snapshot-pre-boot.db

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ETCDCTL_API=3 etcdctl --cacert=/etc/kubernetes/pki/etcd/ca.crt \
                      --cert=/etc/kubernetes/pki/etcd/server.crt \
                      --key=/etc/kubernetes/pki/etcd/server.key \
                      --data-dir=/var/lib/etcd-new \
                      snapshot restore /opt/snapshot-pre-boot.db

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vi /etc/kubernetes/manifests/etcd.yaml

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apiVersion: v1
kind: Pod
metadata:
  annotations:
    kubeadm.kubernetes.io/etcd.advertise-client-urls: https://192.168.49.2:2379
  creationTimestamp: null
  labels:
    component: etcd
    tier: control-plane
  name: etcd
  namespace: kube-system
spec:
  containers:
    - command:
        - etcd
        - --advertise-client-urls=https://192.168.49.2:2379
        - --cert-file=/var/lib/minikube/certs/etcd/server.crt
        - --client-cert-auth=true
        - --data-dir=/var/lib/etcd-new # Change here and...
        - --initial-advertise-peer-urls=https://192.168.49.2:2380
        - --initial-cluster=minikube=https://192.168.49.2:2380
        - --key-file=/var/lib/minikube/certs/etcd/server.key
        - --listen-client-urls=https://127.0.0.1:2379,https://192.168.49.2:2379
        - --listen-metrics-urls=http://127.0.0.1:2381
        - --listen-peer-urls=https://192.168.49.2:2380
        - --name=minikube
        - --peer-cert-file=/var/lib/minikube/certs/etcd/peer.crt
        - --peer-client-cert-auth=true
        - --peer-key-file=/var/lib/minikube/certs/etcd/peer.key
        - --peer-trusted-ca-file=/var/lib/minikube/certs/etcd/ca.crt
        - --proxy-refresh-interval=70000
        - --snapshot-count=10000
        - --trusted-ca-file=/var/lib/minikube/certs/etcd/ca.crt
      image: k8s.gcr.io/etcd:3.4.13-0
      imagePullPolicy: IfNotPresent
      livenessProbe:
        failureThreshold: 8
        httpGet:
          host: 127.0.0.1
          path: /health
          port: 2381
          scheme: HTTP
        initialDelaySeconds: 10
        periodSeconds: 10
        timeoutSeconds: 15
      name: etcd
      resources:
        requests:
          cpu: 100m
          ephemeral-storage: 100Mi
          memory: 100Mi
      startupProbe:
        failureThreshold: 24
        httpGet:
          host: 127.0.0.1
          path: /health
          port: 2381
          scheme: HTTP
        initialDelaySeconds: 10
        periodSeconds: 10
        timeoutSeconds: 15
      volumeMounts:
        - mountPath: /var/lib/etcd-new # Change here and...
          name: etcd-data
        - mountPath: /var/lib/minikube/certs/etcd
          name: etcd-certs
  hostNetwork: true
  priorityClassName: system-node-critical
  volumes:
    - hostPath:
        path: /var/lib/minikube/certs/etcd
        type: DirectoryOrCreate
      name: etcd-certs
    - hostPath:
        path: /var/lib/etcd-new # Change here!
        type: DirectoryOrCreate
      name: etcd-data
status: { }

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cp -ai /etc/kubernetes/manifests/kube-scheduler.yaml /etc/kubernetes/manifests/my-scheduler.yaml

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apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    component: kube-scheduler
    tier: control-plane
  name: my-scheduler # Change here and...
  namespace: kube-system
spec:
  containers:
    - command:
        - kube-scheduler
        - --authentication-kubeconfig=/etc/kubernetes/scheduler.conf
        - --authorization-kubeconfig=/etc/kubernetes/scheduler.conf
        - --bind-address=127.0.0.1
        - --kubeconfig=/etc/kubernetes/scheduler.conf
        - --leader-elect=false # Change here and...
        - --port=30291 # Change here and...
        - --scheduler-name=my-scheduler # Add here and...
        - --secure-port=0 # Add here and...
      image: k8s.gcr.io/kube-scheduler:v1.20.2
      imagePullPolicy: IfNotPresent
      livenessProbe:
        failureThreshold: 8
        httpGet:
          host: 127.0.0.1
          path: /healthz
          port: 10259
          scheme: HTTPS
        initialDelaySeconds: 10
        periodSeconds: 10
        timeoutSeconds: 15
      name: kube-scheduler
      resources:
        requests:
          cpu: 100m
      startupProbe:
        failureThreshold: 24
        httpGet:
          host: 127.0.0.1
          path: /healthz
          port: 10259
          scheme: HTTPS
        initialDelaySeconds: 10
        periodSeconds: 10
        timeoutSeconds: 15
      volumeMounts:
        - mountPath: /etc/kubernetes/scheduler.conf
          name: kubeconfig
          readOnly: true
  hostNetwork: true
  priorityClassName: system-node-critical
  volumes:
    - hostPath:
        path: /etc/kubernetes/scheduler.conf
        type: FileOrCreate
      name: kubeconfig
status: { }

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cd /etc/cni/net.d

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kubectl -n kube-system logs weave-net-8lwzf -c weave | grep range

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cat /etc/kubernetes/manifests/kube-apiserver.yaml | grep range

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kubectl -n kube-system logs kube-proxy-jjwkz | grep proxy

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docker ps -a

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docker logs <container-id>

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kubectl logs nginx-pod

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journalctl -u kubelet

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systemctl status kubelet

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kubectl get netpol

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kubectl run nginx-pod --image=nginx:alpine --restart=Never --namespace=alpha --dry-run=client -o yaml > nginx-pod.yaml

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kubectl exec nginx-pod -- nslookup webapp-service

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kubectl run test-pod --image=busybox --restart=Never --rm -it -- nc -z -v -w 2 webapp-service