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node maintenance

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Dominik Chilla 2021-04-11 20:25:42 +02:00
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README.md
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@ -16,7 +16,6 @@
* [Let´s Encrypt issuer](#cert-manager-le-issuer)
* [Deploying a LE-certificate](#cert-manager-ingress)
* [Troubleshooting](#cert-manager-troubleshooting)
* [Keep your cluster balanced](#keep-cluster-balanced)
* [HELM charts](#helm)
* [Create a chart](#helm-create)
* [Install local chart without packaging](#helm-install-without-packaging)
@ -28,6 +27,8 @@
* [Kubernetes in action](#kubernetes-in-action)
* [Running DaemonSets on `hostPort`](#running-daemonsets)
* [Running StatefulSet with NFS storage](#running-statefulset-nfs)
* [Keep your cluster balanced](#keep-cluster-balanced)
* [Node maintenance](#node-maintenance)
* [What happens if a node goes down?](#what-happens-node-down)
* [Dealing with disruptions](#disruptions)
@ -332,10 +333,6 @@ kubectl -n <stage> describe challenge <object>
After successfull setup perform a TLS-test: `https://www.ssllabs.com/ssltest/index.html`
# Keep your cluster balanced <a name="user-content-keep-cluster-balanced"></a>
Kubernetes, in first place, takes care of high availability, but not of well balance of pod/node. In case of *stateless deployments* [this](https://itnext.io/keep-you-kubernetes-cluster-balanced-the-secret-to-high-availability-17edf60d9cb7) project could be a solution! Pod/Node balance is not a subject to *DaemonSets*.
# HELM charts <a name="user-content-helm"></a>
Docs:
* https://helm.sh/docs/intro/using_helm/
@ -609,6 +606,28 @@ Kubernetes knows something like a `--pod-eviction-timeout`, which is a grace per
Docs: https://kubernetes.io/docs/concepts/scheduling-eviction/eviction-policy/
## Keep your cluster balanced <a name="user-content-keep-cluster-balanced"></a>
Kubernetes, in first place, takes care of high availability, but not of well balance of pod/node. [This](https://itnext.io/keep-you-kubernetes-cluster-balanced-the-secret-to-high-availability-17edf60d9cb7) project could be a solution! Pod/Node balance is not a subject to *DaemonSets*.
## Node maintenance <a name="user-content-node-maintenance"></a>
*Mark* a node for maintenance:
```
$ kubectl drain k3s-node2 --ignore-daemonsets
$ kubectl get node
NAME STATUS ROLES AGE VERSION
k3s-node1 Ready <none> 105d v1.19.5+k3s2
k3s-master Ready master 105d v1.19.5+k3s2
k3s-node2 Ready,SchedulingDisabled <none> 105d v1.19.5+k3s
```
All Deployment as well as StatefulSet pods have been rescheduled on remaining nodes. DaemonSet pods were not touched! Node maintenance can be performed now.
To bring the maintained node back in cluster:
```
$ kubectl uncordon k3s-node2
node/k3s-node2 uncordoned
```
## Dealing with disruptions <a name="user-content-disruptions"></a>
* https://kubernetes.io/docs/concepts/workloads/pods/disruptions/
* https://kubernetes.io/docs/tasks/administer-cluster/safely-drain-node/