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Services & Networking (20%)

kubernetes.io > Documentation > Reference > kubectl CLI > kubectl Cheat Sheet

kubernetes.io > Documentation > Tasks > Monitoring, Logging, and Debugging > Get a Shell to a Running Container

kubernetes.io > Documentation > Tasks > Access Applications in a Cluster > Configure Access to Multiple Clusters

kubernetes.io > Documentation > Tasks > Access Applications in a Cluster > Accessing Clusters using API

kubernetes.io > Documentation > Tasks > Access Applications in a Cluster > Use Port Forwarding to Access Applications in a Cluster

Drain a node for maintenance named node1.mylabserver.com

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kubectl drain node1.mylabserver.com --ignore-daemonsets --force

Put the node node1.mylabserver.com back into service, so pods can be scheduled to it

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kubectl uncordon node1.mylabserver.com

Updgrade kubeadm to version 1.18.6

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sudo apt install -y kubeadm --allow-change-held-packages kubeadm=1.18.6-00

Plan and upgrade the control plane components with kubeadm to version 1.18.6

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sudo kubeadm upgrade plan

sudo kubeadm upgrade apply v1.18.6

Update kubelet to version 1.18.6

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sudo apt install kubelet=1.18.6-00

Update kubectl to version 1.18.6

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sudo apt install kubectl=1.18.6-00

Restart kubelet on the node

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sudo systemctl daemon-reload

sudo systemctl restart kubelet

Upgrade the kubelet configuration on a worker node

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sudo kubeadm upgrade node

List all namespaces in your cluster

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kubectl get ns

List all pod in all namespaces

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kubectl get po --all-namespaces

Create a new namespace named web

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kubectl create ns web

Look up the value for the key cluster.name in the etcd cluster and backup etcd

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ETCDCTL_API=3 etcdctl get cluster.name \
--endpoints=https://10.0.1.101:2379 \
--cacert=/home/cloud_user/etcd-certs/etcd-ca.pem \
--cert=/home/cloud_user/etcd-certs/etcd-server.crt \
--key=/home/cloud_user/etcd-certs/etcd-server.key

ETCDCTL_API=3 etcdctl snapshot save /home/cloud_user/etcd_backup.db \
--endpoints=https://10.0.1.101:2379 \
--cacert=/home/cloud_user/etcd-certs/etcd-ca.pem \
--cert=/home/cloud_user/etcd-certs/etcd-server.crt \
--key=/home/cloud_user/etcd-certs/etcd-server.key

Reset etcd and remove all data from the etcd

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sudo systemctl stop etcd

sudo rm -rf /var/lib/etcd

Restore an etcd store from backup.

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# spin up a temporary etcd cluster and save the data from the backup file to a new directory (/var/lib/etcd)
sudo ETCDCTL_API=3 etcdctl snapshot restore /home/cloud_user/etcd_backup.db \
--initial-cluster etcd-restore=https://10.0.1.101:2380 \
--initial-advertise-peer-urls https://10.0.1.101:2380 \
--name etcd-restore \
--data-dir /var/lib/etcd

# set ownership of the new data directory
sudo chown -R etcd:etcd /var/lib/etcd

# start etcd
sudo systemctl start etcd

# Verify the data was restored
ETCDCTL_API=3 etcdctl get cluster.name \
--endpoints=https://10.0.1.101:2379 \
--cacert=/home/cloud_user/etcd-certs/etcd-ca.pem \
--cert=/home/cloud_user/etcd-certs/etcd-server.crt \
--key=/home/cloud_user/etcd-certs/etcd-server.key

MORE CKA EXAM EXERCISES HERE