• Lab: Install Kubernetes On Ubuntu

#etcd backup and restore brief
export ETCDCTL_API=3  # needed to specify etcd api versions, not sure if it is needed anylonger with k8s 1.19+ 
etcdctl snapshot save -h   #find save options
etcdctl snapshot restore -h  #find restore options

## possible example of save, options will change depending on cluster context, as TLS is used need to give ca,crt, and key paths
etcdctl snapshot save /backup/snapshot.db  --cert=/etc/kubernetes/pki/etcd/server.crt  --key=/etc/kubernetes/pki/etcd/server.key --      cacert=/etc/kubernetes/pki/etcd/ca.crt


# evicting pods/nodes and bringing back node back to cluster
kubectl drain  <node># to drain a node
kubectl uncordon  <node> # to return a node after updates back to the cluster from unscheduled state to Ready
kubectl cordon  <node>   # to not schedule new pods on a node

#backup/restore the cluster (e.g. the state of the cluster in etcd)


# upgrade kubernetes worker node
kubectl drain <node>
apt-get upgrade -y kubeadm=<k8s-version-to-upgrade>
apt-get upgrade -y kubelet=<k8s-version-to-upgrade>
kubeadm upgrade node config --kubelet-version <k8s-version-to-upgrade>
systemctl restart kubelet
kubectl uncordon <node>


#kubeadm upgrade steps
kubeadm upgrade plan
kubeadm upgrade apply

Workloads & Scheduling – 15%

1. Understand deployments and how to perform rolling update and rollbacks
2. Use ConfigMaps and Secrets to configure applications

• configure a pod with a configmap
• configure a pod with a secret

3. Know how to scale applications

• scaling a statefulset
• scaling a replicaset

4. Understand the primitives used to create robust, self-healing, application deployments

• Replicaset
• Deployments
• Statefulsets
• Daemonset

5. Understand how resource limits can affect Pod scheduling
6. Awareness of manifest management and common templating tools

• Kustomize
  • Kustomize Blog
• manage kubernetes objects
• Install service catalog using helm
  • Non-k8s.io resource: CNCF Kubecon video: An introduction to Helm - Bridget Kromhout, Microsoft & Marc Khouzam, City of Montreal

• Non-k8s.io resource: External resource: templating-yaml-with-code

Services & Networking – 20%

1. Understand host networking configuration on the cluster nodes

2. Understand connectivity between Pods

   • The concept of Pods networking

3. Understand ClusterIP, NodePort, LoadBalancer service types and endpoints

   • service

4. Know how to use Ingress controllers and Ingress resources

   • Ingress concepts

5. Know how to configure and use CoreDNS

6. Choose an appropriate container network interface plugin

   • Kubernetes Networking Intro and Deep-Dive - Bowei Du & Tim Hockin, Google
   • Kubernetes and Networks: why is this so dang hard?
   • Kubecon Eu 2020 Tutorial: Communication Is Key - Understanding Kubernetes Networking - Jeff Poole, Vivint Smart Home

Storage – 10%

1. Understand storage classes, persistent volumes
2. Understand volume mode, access modes and reclaim policies for volumes
3. Understand persistent volume claims primitive
4. Know how to configure applications with persistent storage

#### Storage Class example
#

#### Persistent Volume Claim example
#
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: local-pvc
spec:
  accessModes:
  - ReadWriteOnce
  storageClassName: local-storage-sc
  resources:
    requests:
      storage: 100Mi

## Persistent Volume example
#
apiVersion: v1
kind: PersistentVolume
metadata:
  name: local-pv
spec:
  accessModes:
  - ReadWriteOnce
  capacity:
    storage: 200Mi
  local:
    path: /data/pv/disk021
  persistentVolumeReclaimPolicy: Retain
  storageClassName: local-storage-sc
  volumeMode: Filesystem

###  Pod using the pvc
#
apiVersion: v1
kind: Pod
metadata:
  name: nginx
  labels:
    name: nginx
spec:
  containers:
  - name: nginx
    image: nginx
    volumeMounts:
      - name: local-persistent-storage
        mountPath: /var/www/html
  volumes:
    - name: local-persistent-storage
      persistentVolumeClaim:
        claimName: local-pvc

Troubleshooting – 30%

1. Evaluate cluster and node logging
2. Understand how to monitor applications
3. Manage container stdout & stderr logs
4. Troubleshoot application failure
   • Pending or termintated pods
5. Troubleshoot cluster component failure
6. Troubleshoot networking
   • DNS troubleshooting

Tips:

practice practice practice

Get familiar with:

• Familiarize yourself with the documentation, initially concepts and mostly tasks, kubectl explain command, kubectl cheatsheet, and kubectl commands reference
  • https://kubernetes.io/docs/concepts/
  • https://kubernetes.io/docs/tasks/
  • https://kubernetes.io/docs/user-guide/kubectl-cheatsheet/
  • https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands
• kubectl api-versions and kubectl api-resources wih grep for a specific resoruce e.g. pv, pvc, deployment, storageclass, ..etc can help figure out the