Skip to content

Latest commit

 

History

History
179 lines (132 loc) · 7.47 KB

k8s-installation-guides.md

File metadata and controls

179 lines (132 loc) · 7.47 KB
Raw

Guides of Kubernetes Deployment on Ubuntu 18.04

Go to https://phoenixnap.com/kb/install-kubernetes-on-ubuntu for reference.

An Example on the Symphony Cluster

Install Docker

  • Update the package list with the command sudo apt update.
  • Install Docker with the command: sudo apt install docker.io.
  • Check the installation and version by entering the following: docker -v.
    • 19.03.2: dvorak, dvorak-2-2, dvorak-2-3, dvorak-1-1, dvorak-1-2, dvorak-1-4
    • 19.03.4: dvorak-1-3
    • 19.03.5: dvorak-2-1, dvorak-2-4
  • Repeat the process on each server that will act as a node in the Kubernetes cluster.

Start and Enable Docker

  • Set Docker to launch at boot by entering the following command: sudo systemctl enable docker.
  • Verify Docker is running: sudo systemctl status docker.
  • Start Docker if it's not running: sudo systemctl start docker.
  • Repeat the process on each server that will act as a node in the Kubernetes cluster.

Install Kubernetes

  • Add Kubernetes signing key: curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add.
  • Add Software Repositories because Kubernetes is not included in the default repositories: sudo apt-add-repository "deb http://apt.kubernetes.io/ kubernetes-xenial main".
  • Install Kubernetes Admin, which is a tool that helps initialize a cluster, with the command:
  • Repeat for all server nodes.

Deploy Kubernetes

  • [ALL] Disable the swap memory on each server: sudo swapoff -a.
  • [ALL] Assign unique hostname for each server node: sudo hostnamectl set-hostname xxx.
  • [MASTER] Initialize Kubernetes on the master node:
    • sudo kubeadm init --pod-network-cidr=10.244.0.0/16: Once this command finishes, it will display a kubeadm join message at the end. Make a note of the whole entry because it will be used to join the worker nodes to the cluster.
      • --pod-network-cidr=10.244.0.0/16 is for flannel virtual network to work.
    • Create a directory for the cluster:
      • mkdir -p $HOME/.kube;
      • sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config;
      • sudo chown $(id -u):$(id -g) $HOME/.kube/config;
  • [MASTER] Deploy pod network to the cluster. A pod network is a way to allow communication between different nodes in the cluster.
    • sudo kubectl apply -f https://github.com/raw/coreos/flannel/master/Documentation/kube-flannel.yml;
    • kubectl get pods --all-namespaces (verify the pod network is working);
  • [WORKER] Connect each worker node to the cluster.
    • sudo kubeadm join --discovery-token abcdef.1234567890abcdef --discovery-token-ca-cert-hash sha256:1234..cdef 1.2.3.4:6443 (replace the alphanumeric codes with those from your master server during initialization);
    • If you forget the command or the token is expired, run kubeadm token create --print-join-command from the master server.
  • [MASTER] Check the worker nodes joined to the clusster: kubectl get nodes.

By going through all the instructions above, a Kubernetes cluster should be installed, deployed and ready for use.

[Optional] In order to get a kubectl on some other computer (e.g. laptop) to talk to your cluster, you need to copy the administrator kubeconfig file from your control-plane node to your workstation like this:

scp root@<control-plane-host>:/etc/kubernetes/admin.conf .
kubectl --kubeconfig ./admin.conf get nodes

Cluster Setup

The example Kubernetes cluster consists of one master node and four worker nodes, all with version v1.17.2.

  • Master node(s): dvorak
  • Worker node(s): dvorak-2-1, dvorak-2-2, dvorak-2-3, dvorak-2-4

Commands to join worker nodes to the Kubernetes cluster (run as root):

kubeadm join 192.17.100.193:6443 --token 6nyoyd.m9y4647myjz72bvq \
    --discovery-token-ca-cert-hash sha256:15c534de029ce6056404b1c8be0b2a9b63007b0166a48189bd613492d709f961

Commands to generate the above join-command or retrieve the token (run from the master node):

kubeadm token create --print-join-command

Show all nodes:

ubuntu@dvorak:~$ kubectl get nodes
NAME         STATUS   ROLES    AGE   VERSION
dvorak       Ready    master   22m   v1.17.2
dvorak-2-1   Ready    worker   18m   v1.17.2
dvorak-2-2   Ready    worker   16m   v1.17.2
dvorak-2-3   Ready    worker   16m   v1.17.2
dvorak-2-4   Ready    worker   15m   v1.17.2

Miscellaneous

Invalid Signature/Public Key Not Available

If you see error messages like:

W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://dl.google.com/linux/chrome/deb stable Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 78BD65473CB3BD13
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: https://dl.yarnpkg.com/debian stable InRelease: The following signatures were invalid: EXPKEYSIG 23E7166788B63E1E Yarn Packaging <yarn@dan.cx>

Adding the key using apt-key can solve the problem: sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys KEY.

Remove Previously Installed Kubernetes

To remove the outdated Kubernetes installed on the node, execute sudo apt --purge remove kubeadm kubectl kubelet.

Add/Remove Labels to Nodes in Kubernetes

kubectl label node dvorak-2-1 labelname=labelvalue             # add label
kubectl label node dvorak-2-1 labelname-                       # remove label
kubectl label node dvorak-2-1 node-role.kubernetes.io/worker=  # label as worker

Commands on Displaying Machine/Server Info

  • hostnamectl status
ubuntu@dvorak-2-4:~$ sudo hostnamectl status
   Static hostname: dvorak-2-4
         Icon name: computer-server
           Chassis: server
        Machine ID: 052dfdf6532f42dc8b9098c2e9f2cede
           Boot ID: d9a6da775f214be0b54b9a27c7ce2040
  Operating System: Ubuntu 18.04.3 LTS
            Kernel: Linux 4.15.0-70-generic
      Architecture: x86-64

Join Cluster

Sometimes you cannot join the cluster and this is because your install a newer version of Kubernetes than the cluster master has. To install a specific version of Kubernetes, run:

curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add - && \
    echo "deb http://apt.kubernetes.io/ kubernetes-xenial main" | sudo tee /etc/apt/sources.list.d/kubernetes.list && \
    sudo apt-get update -q && \
    sudo apt-get install -qy kubelet=<version> kubectl=<version> kubeadm=<version>

You can get the exact version time from:

curl -s https://packages.cloud.google.com/apt/dists/kubernetes-xenial/main/binary-amd64/Packages | grep Version | awk '{print $2}'

Completely Remove Kubernetes

First delete the node if there is:

kubectl drain <node name> — delete-local-data — force — ignore-daemonsets
kubectl delete node <node name>

Then remove kubeadm kubectl kubelet and related packages completely:

kubeadm reset

# on debian base 
sudo apt-get purge kubeadm kubectl kubelet kubernetes-cni kube* 
# on centos base
sudo yum remove kubeadm kubectl kubelet kubernetes-cni kube*

# on debian base
sudo apt-get autoremove
# on centos base
sudo yum autoremove
 
sudo rm -rf ~/.kube