====== Kubernetes ======

===== Installation =====

Add the Repository,install "kubelet" + "kubeadm" + "kubectl" and set the updates on hold
<code>
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 kubeadm kubectl
  apt-mark hold kubelet kubeadm kubectl
</code>

===== Configuration =====

==== master ====

Pull images used by kubeadm
<code>
kubeadm config images pull
</code>

Set up the ip configuration, the "apiserver-advertise-address" has to be your management ip
<code>
kubeadm init --apiserver-advertise-address=10.0.0.2 --pod-network-cidr=192.168.0.0/16                               
#kubeadm init --pod-network-cidr=192.168.0.0/16
</code>

You may run into the following warnings and errors
<code>
[init] Using Kubernetes version: v1.16.2
[preflight] Running pre-flight checks
        [WARNING IsDockerSystemdCheck]: detected "cgroupfs" as the Docker cgroup driver. The recommended driver is "systemd". Please follow the guide at https://kubernetes.io/docs/setup/cri/
        [WARNING SystemVerification]: this Docker version is not on the list of validated versions: 19.03.4. Latest validated version: 18.09
error execution phase preflight: [preflight] Some fatal errors occurred:
        [ERROR Swap]: running with swap on is not supported. Please disable swap
[preflight] If you know what you are doing, you can make a check non-fatal with `--ignore-preflight-errors=...`
To see the stack trace of this error execute with --v=5 or higher
</code>

To fix the error, disable swap
<code>
swapoff -a

#should be 0 now
free -m
              total        used        free      shared  buff/cache   available
Mem:           xxxx         xxx        xxxx         xxx        xxxx        xxxx
Swap:             0           0           0

</code>

Execute the ip configuration again, which should now be possible.

If the initialization was successful, create a new user.
<code>
useradd -s /bin/bash -m kubernetes                                       
su - kubernetes
mkdir -p $HOME/.kube
sudo cp -i /etc/kubernetes/admin.conf $HOME/.kube/config
sudo chown $(id -u):$(id -g) $HOME/.kube/config
</code>

Next you need to deploy a pod network.\\
Find some here: https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/#pod-network

I use calico, which can be deployed via
<code>
kubectl apply -f https://docs.projectcalico.org/v3.8/manifests/calico.yaml
</code>

==== Dashboard ====

Find the dashboard for your kubernetes version here:\\
[[https://github.com/kubernetes/dashboard/releases]]

You can see your version via 
<code>
kubeadm version
</code>



===== Commands =====

^  Command  ^  Function  ^
|  kubectl get pods --all-namespaces   |  show pods   |
|  kubeadm reset   |  reverts changes made via "kubeadm init" and "kubeadm join"   |

===== Troubleshooting =====

==== Placeholder ====

__Reason:__ \\
 \\

__Fix:__ \\

\\

===== Offene Fragen... =====

  * cgroup driver?!
[[https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/install-kubeadm/#configure-cgroup-driver-used-by-kubelet-on-control-plane-node]]

Please mind, that you only have to do that if the cgroup driver of your CRI is not cgroupfs, because that is the default value in the kubelet already.

ABER

[WARNING IsDockerSystemdCheck]: detected "cgroupfs" as the Docker cgroup driver. The recommended driver is "systemd". Please follow the guide at https://kubernetes.io/docs/setup/cri/

Reason why

https://github.com/kubernetes/kubeadm/issues/1394#issuecomment-462878219



  * validated version of docker?

[WARNING SystemVerification]: this Docker version is not on the list of validated versions: 19.03.4. Latest validated version: 18.09

  * management ip

https://github.com/kubernetes/kubernetes/issues/33618





kubectl edit deployment kubernetes-dashboard -n kube-system NAMESPACE anders!!!
kein ttl im dashboard